Hosts

Q&A

Hosts
Description

Pakistan

Prevention

Eradicate weeds from field in the beginning of the crop at early stage
Destroy the debris of the crop after harvesting
Grow only recommended varieties e.g. melon 1, sugarbaby, Ravi, T-96, Black Chairman, Jaguar, Black happy
Avoid sowing alternate host plants of white fly, like cabbage,cotton and okra, near melon crop

Monitoring

Attack of insects can be seen on leaves, flowers and tender branches
Infected plants look dirty and opaque
Sticky material comes from the body of insects and black fungus appears on leaves
Adults are small whitish flying insects and young ones are yellow dot like non-motile insects present on the underside of the leaves
Take action when 5 adults, young or both are observed per leaf (ETL)

Control

Promote the growth of beneficial insects (chrysoperla, ladybird beetle) by justifying the use of pesticides

Hosts
Description

C. imbricatus is a coarse, rhizomatous perennial, 70-150 cm tall;rhizomes short, 1-3 cm long, 5-10 mm thick, hardened;roots coarse. Culms erect, trigonous, often subtriquetrous distally, firm, coarsely ribbed, smooth, 3.5 -10 mm wide, sheathing bases 1-3 cm wide. Leaves 3-7;sheaths eligulate, spongy-thickened and purple-black proximately, fading to brown streaked with black distally;ligule absent;blades linear, folded to V shaped proximally, plicate distally, 35-90 cm ? 4-15 (-18) mm, with numerous cross veinlets, scabrous on the margins, abaxial mid-vein, and adaxial lateral veins, long-attenuate to triquetrous apex. Inflorescence a compound umbel-like corymb with ascending rays, 12-30 ?14-30 (-40) cm;involucral bracts 5-10, leaf-like, spreading, ascending to horizontal, the lowermost to 90 cm long;rays 6-12, to 25 cm long;spikes linear-cylindric, 1-6 (-8) cm ? 3-10 (-15) mm, in subradiate groups of (1-) 3-20 at ray tips, with (20-) 30-130 (-160) densely disposed spikelet, compressed, often slightly twisted, 3-6 ? 1-1.4 mm, acute to obtuse at apex, obtuse at base, with 8-22 florets. Stamens 3, the anthers 0.2 - 0.5 mm long, apiculate;styles 3-branched. Achene trigonous, dorsi-ventrally compressed, with the adaxial face plane and the abaxial faces broadly rounded, ellipsoid to ellipsoid-obovoid, 0.5-0.6 ?0.3-0.4 mm, very finely puncticulate to essentially smooth and glossy at maturity, dull whitish to stramineous (Acevedo-Rodr’guez and Strong, 2005).

Hosts

C. imbricatus is a common weed in rice plantations and banana fields in tropical and temperate Asia (Mangoensoekardjo and Pancho, 1975;Soerjani et al., 1987;Noda et al., 1994;Li, 1998;Koo et al., 2000).


Source: cabi.org
Hosts
Description

G. physocarpus is an upright, soft shrub 0.5 to 2 m tall with a fibrous rootstock. Young stems and inflorescences pubescent. Petiole approximately 1 cm;leaf blade narrowly lanceolate, 5-l0 ? 0.6-1.5 cm, adaxially sparsely pubescent, abaxially hairy along midvein, both ends tapering or acute. Branches are pale yellowish green and hollow. The leaves are light green, opposite, and narrowly oblong to lance-shaped. Flowers in pendulous clusters, corolla white, 1.4-2 cm in diameter;lobes ovate, 8-10 mm, reflexed, margin densely bearded. Corona lobes white, inner margin of hoodlike apex with 2, short, recurved or straight cusps, with a large adaxial nectary. In the centre of the flower is the corona, consisting of five pouched lobes that develop from the petals. The petals are white and the corona is suffused with pink or purple. The corona surrounds the stamens and carpels composed of ovary, style and stigma. The filaments of the stamens are fused to form a staminal column which encloses the female part. The female part consists of two free carpels, the tips of which are united and enlarged to form the style head. This is the yellowish, 5-lobed disc that can be seen at the centre of the flower. The anthers are fused to the style head. The pollen grains of each anther lobe are united to form two waxy masses known as pollinia or pollen sacs. Fruits are large spherical inflated follicles, 6-8 ? 2.5-5 cm, base oblique, apex rounded, beakless;pericarp with soft bristles or spines, minutely tomentose when young, glabrescent when ripe. Seeds ovate, approximately 5 mm;coma shining white, approximately 5 mm, each with a tuft of long silky hairs attached at one end (Notten, 2010;Flora of China Editorial Committee, 2014).

Hosts

G. physocarpus was recorded growing as a weed in pastures and in crops such as sugarcane (Motooka et al., 2003;Flora of China, 2014). It is also an environmental weed affecting principally lowland dry forests, coastal forests and wetlands (DAISIE, 2014;PROTA;2014;USDA-ARS, 2014).


Source: cabi.org
Hosts
Description

Evergreen, fast-growing tree, up to 12 m height, with single or multi-stemmed trunks, and greenish bark. Leaves are alternate with petioles up to 61 cm long, palmately compound with mostly 7-16 leaflets, these shiny, light green, oblanceolate, up to 30 cm long, and entire margins (or sparsely toothed when young). Flowers are borne in dense clusters that form a large, red, showy inflorescence at stem tips above foliage. Fruits are purplish black, round, fleshy drupes up to 7 mm in diameter (Gilman and Watson, 1994).

Hosts

S. actinophylla has been documented shading out the threatened species nodding pinweed (Lechua cernua) in Florida (Langeland et al., 2008). In addition, seedlings of this species may germinate in the crotches or branches of large trees and in this case the plant will grow as an epiphyte that can strangle and eventually kill host trees (Menninger, 1971).


Source: cabi.org
Hosts
Description

The following description is from Flora of China Editorial Committee (2016)

Hosts

M. jalapa is reported as being a weed in apple orchards (CONABIO, 2016). Its allelopathic effects can inhibit the germination and growth of wheat and cabbage (Xu et al., 2008).


Source: cabi.org
Hosts
Description

The adult of M. semipunctatum is a wingless, black beetle with a convex, often elongate, dull to shining, glabrous body. Females are 15Ð30 mm long and males 15Ð26 mm long. M. semipunctatum has small pronotal spines, large punctures on the disk of the pronotum, and a lack of pubescent patches on the coxae. There are some geographical variations in morphology, in northern populations, punctuation of the pronotum is denser and the integument is often duller than in southern populations (Linsley and Chemsak, 1984).

Symptons

Adults feed on the succulent portions of cacti and the larvae feed near the root collar and within the stems. Feeding activity by boring larvae of M. semipunctatum on Opuntia can be recognized above ground by the tar-like excrement of the larvae and the fluids expelled by the plant from the wounds they create (Evans and Hogue, 2006). Adult feeding by Moneilema spp. can often result in severance of the joints in Opuntia, which fall to the ground and frequently take root, aiding dissemination of the plants. Heavy infestations of the beetles can kill the plants (Woodruff, 1966). Although M. semipunctatum is not generally lethal for Opuntia plants, which can propagate vegetatively, the effect of the beetle on Sclerocactus varies with the host species (Woodruff, 2010). Infestation by M. semipunctatum has been reported as a significant but localized source of mortality of all Sclerocactus species on the Colorado Plateau, particularly of larger, mature, reproducing individuals (Utah Ecological Services Field Office, 2010).


Source: cabi.org
Hosts
Title: Oryza barthii
Description

From Flora Zambesiaca (2013)

Hosts

O. barthii is a major weed of rice in West Africa. It is apparently less serious in other parts of Africa, and not recorded as a significant weed in any other crops.


Source: cabi.org
Title: Oryza barthii
Hosts
Description

Herb with stems decumbent to ascending, many-branched, 2-6 dm long, hirsute. Leaves ovate to narrowly ovate, 1-3.5(-6) cm long, 0.6-2.3(-3.5) cm wide, hirsute, more densely so along veins on lower surface, margins crenate, apex rounded, base truncate to subcordate, petioles 0-2(-3.5) cm long. Flowers usually 3-6 in verticillasters, these arranged in terminal, leafy, spike-like inflorescences, calyx usually tinged purple, campanulate, 5-6 mm long, hirsute, especially along nerves, cleft ca. 1/2 its length, the teeth slightly unequal, lanceolate, upper lobes ca. 2.7-2.8 mm long, lower lobe ca. 2.2-2.3 mm long, corolla pink, rose, or blue, 5-7 mm long, upper lip erect, median lobe of lower lip ovate, faintly spotted red near base. Nutlets black, shiny, muricate, obovoid, ca. 2 mm long. [Wagner et al., 2014]

Hosts

S. arvensis is an agricultural weed in Europe including Italy and Slovenia, where it invades carrot crops (Randall, 2012). In Wales, UK, S. arvensis was identified as an abundant arable weed that affects spring barley and grass crops (Hurford, 2007).


Source: cabi.org
Hosts
Description

C. madagascariensis is a twining woody vine or scandent shrub, 6-8 m in length, with abundant milky latex. Stems are cylindrical, glabrous, reddish brown, with few lenticels. Leaves are opposite;blades 4-10 ? 2-4.7 cm, elliptical, oblong, or ovate, coriaceous, glabrous, the apex short-acuminate, obtuse, or rounded. The margins are entire;venation pinnate, with14-16 pairs of secondary veins;upper surface dull;lower surface pale, with obscure venation;petioles glabrous, 0.6-1.5 cm long;stipules minute, intrapetiolar. Flowers are arranged in pedunculate cymes;bracts foliaceous, lanceolate, approximately 5 mm long. Calyx green, campanulate, the sepals lanceolate, pubescent, 0.5-1.5 cm long;corolla 3-6 cm long, violet, the tube darker inside, the lobes abaxially whitish in the overlapping portion;corona with 5 simple lobes, approximately 1 cm long. Two follicles, divergent, brown when mature, 5.8-13 cm long, woody. Seeds are reddish brown, ovate-lanceolate, 3 mm long, with long, cream colored silky hairs (Acevedo-Rodr’guez, 2005).

Hosts

C. madagascariensis is not a weed of agricultural crops. However, in Australia, both C. grandiflora and C. madagascariensis can smother and out-compete both wild and pasture grasses, being a serious problem in pasture lands. These species are an expensive problem for ranchers in Australia who must control these plants which are toxic to cattle and horses (Australian Weeds Committee, 2012).

Biological Control
In Australia, biological control has been used in both the species C. grandiflora and C. madagascariensis. The rubber vine rust (Maravalia cryptostegiae) has been used for biological control over a wide area in Queensland. Yellow spores form under leaves eventually causing defoliation, reducing seed production, causing dieback of stems, and killing young seedlings. In addition the larvae of the moth Euclasta whalleyi have been used in combination with the rust. This larvae feed on leaves. These agents do not kill established plants, but do cause abnormal defoliation and lead to reduced seed production. Their success and potential damage depends on their abundance (Starr et al., 2003). In Brazil, two fungal pathogens Colletotrichum gloeosporioides (Glomerella cingulata) and Pseudocercospora cryptostegiae-madagascariensis have been targeted as potential biological control agents (Silva et al., 2008).

Source: cabi.org
Hosts
Title: Urena lobata
Description

Erect, woody perennial herb or small shrub, up to 3 m tall, but usually around 1.5 m tall. Stems and leaves are covered with star-shaped (stellate) hairs, often many branched at the base. Leaves are simple, alternate, with the upper surface rough and the lower surface grayish, broadly ovate, often with 3-5 shallow, angular lobes at apex, up to 10 cm long, margins finely toothed, bases heart shaped, petioles up to 5 cm long, stipules tiny. Flowers are small, showy, hibiscus-like, solitary on short stalks in leaf axils, subtended by 5 basally united (involucral) bracts up to 0.7 cm, calyx 5-lobed, hairy, 5 petals, rose or pink, darker at the base, rounded, up to 1.5 cm long, stamens fused into an obvious pink column beneath a 5-lobed style. Fruits are small, barbed, spiny capsules, up to 1 cm across, with 5 prominent segments each containing 1 dark brown seed (Francis, 2000, Langeland et al., 2008, Queensland Department of Primary Industries and Fisheries, 2011).

Hosts

U. lobata is a severe weed in pastures, sugarcane fields, coffee plantations, rice plantations, and perennial crop plantations in many countries around the world (Henty and Pritchard, 1973;Fournet and Hammerton, 1991;Martin and Pol, 2009;Randall, 2012). It is considered a weed in forest plantations in Bangladesh (Akter and Zuberi, 2009) and India (Chandra-Sekar, 2012). U. lobata is also classified as a noxious environmental weed because it has the potential to alter native plant communities by displacing and out-competing native species, changing community structures, and altering ecological functions (Austin, 1999;Florida Exotic Pest Plant Council, 2011;USDA-NRCS;2012).


Source: cabi.org
Title: Urena lobata
Description


Phenotypic Characteristics
X. citri is a Gram-negative, straight, rod-shaped bacterium measuring 1.5-2.0 x 0.5-0.75 µm. It is motile by means of a single, polar flagellum. It shares many physiological and biochemical properties with other members of the genus Xanthomonas. It is chemoorganotrophic and obligately aerobic with the oxidative metabolism of glucose. Colonies are formed on nutrient agar plates containing glucose and are creamy-yellow with copious slime. The yellow pigment is xanthomonadin. Catalase is positive, but Kovacs' oxidase is negative or weak;nitrate reduction is negative. Asparagine is not used as a sole source of carbon and nitrogen simultaneously;various carbohydrates and organic acids are used as a sole source of carbon. Hydrolysis of starch, casein, Tween 80 and aesculin is positive. Gelatine and pectate gel are liquefied. Growth requires methionine or cysteine and is inhibited by 0.02% triphenyltetrazolium chloride. Biovars may be distinguished by utilization of mannitol. For further information on the bacteriological properties of X. citri, see Goto (1992).
Strains of groups B, C and D have many properties in common with group A, the differences being detected by the utilization of only a few carbohydrates (Goto et al., 1980).
Molecular Characterization
Features of citrus-attacking xanthomonads including X. citri and the genus Xanthomonas as a whole, have been characterized at the molecular level for the development of quick and accurate methods for reclassification and identification. The procedures include DNA-DNA hybridization (Vauterin et al., 1995), genomic fingerprinting (Lazo et al., 1987), fatty acid profiling (Yang et al., 1993), SDS-PAGE (Vauterin et al., 1991) and isoenzyme profiles (Kubicek et al., 1989) and monoclonal antibodies (Alverez et al., 1991).
Bacteriophages
Phage-typing is applicable to X. citri with greater reliability than any other plant pathogenic bacterium investigated so far. Many strains of X. citri are lysogenic (Okabe, 1961). Two virulent phages, Cp1 and Cp2, can infect 98% of the strains isolated in Japan (Wakimoto 1967). Similar results were also obtained in Taiwan (Wu et al., 1993). The filamentous temperate phages and their molecular traits have been studied in detail (Kuo et al., 1994;Wu et al., 1996). Phage Cp3 is specific to the canker B strains (Goto et al., 1980). No phages specific to canker C and D strains have been isolated.

Recognition


Methods of detecting X. citri from natural habitats include leaf-infiltration, bacteriophage, fluorescent antibody and ELISA (Goto, 1992). The polymerase chain reaction and dot blot immunobinding assay (DIA) were developed for rapid, sensitive, and specific detection of the pathogen. The detectable limits were reported to be around 30 c.f.u./ml for the former and 1000 c.f.u./ml for the latter (Hartung et al., 1993, 1996;Wang et al., 1997;Miyoshi et al., 1998).

Symptons


Canker lesions begin as light yellow, raised, spongy eruptions on the surface of leaves, twigs and fruits. The lesions continuously enlarge from pin-point size over several months and can be of many different sizes based on the age of the lesion. As the lesions enlarge, the spongy eruptions begin to collapse, and brown depressions appear in their central portion, forming a crater-like appearance. The edges of the lesions remain raised above the surface of host tissue and the area around the raised portion of the lesion may have a greasy appearance. The lesions become surrounded by characteristic yellow halos. Canker lesions retain the erupted and spongy appearance under dry conditions, such as in a greenhouse;whereas they quickly enlarge and turn to flat lesions with a water-soaked appearance with frequent rain. Canker lesions vary in maximum size from 5 to 10 mm, depending on the susceptibility of the host plant. The symptoms are similar on leaves, fruit and stems.
Canker lesions are histologically characterized by the development of a large number of hypertrophic cells and a small number of hyperplastic cells. At an early stage of infection, the cells increase in size and the nuclei and nucleoids stain more easily;there is also an increase in the amount of cytoplasm synchronized with rapid enlargement. However, these hypertrophied cells do not divide;cell division is only detected in the peripheral areas of lesions adjacent to healthy tissue.
The lesions of canker B, C and D are similar in appearance and histology to those of canker A (Goto, 1992).
Reddy and Naidu (1986) reported canker lesions on roots;however, this has not been confirmed.

Impact

X. citri is a bacterial pathogen that causes citrus canker - a disease which results in heavy economic losses to the citrus industry worldwide either in terms of damage to trees (particularly reduced fruit production), reduced access to export markets, or the costs of its prevention and control. Lesions appear on leaves, twigs and fruit which cause defoliation, premature fruit abscission and blemished fruit, and can eventually kill the tree. It is introduced to new areas through the movement of infected citrus fruits and seedlings, and inadvertent re-introduction is highly likely despite the quarantine restrictions that are in place in many countries. Locally, X. citri is rapidly disseminated by rainwater running over the surfaces of lesions and splashing onto uninfected shoots;spread is therefore greatest under conditions of hight temperature, heavy rainfall and strong winds. Some areas of the world have eradicated citrus canker, others have on-going eradication programmes, however, this pathogen remains a threat to all citrus-growing regions.

Hosts


The Citrus species listed in the table of hosts, and the following hybrids, are natural hosts of X. citri, with varying degrees of susceptibility to X. citri. In addition to host plant, susceptibility is also affected by the plant part affected, whether leaves, fruits or twigs. Reddy and Naidu (1986) reported canker lesions on roots but this has not been confirmed.
Hybrids:
C. aurantiifolia x Microcitrus australasica (Faustrime), C. limon x M. australasica (Faustrimon), C. madurensis x M. australasica (Faustrimedin), C. sinensis x Poncirus trifoliata (Citrange), C. paradisi x P. trifoliata (Citrumelo) (Schoulties et al., 1987), C. aurantifolium x P. trifoliata (Citradia), C. nobilis x P. trifoliata (Citrandin), C. unshiu x P. trifoliata (Citrunshu), Citrange x P. trifoliata (Cicitrangle), C. adurensis x Citrange (Citrangedin), C. deliciosa x Citrange (Citrangarin), C. unshiu x Citrange (Citranguma), Fortunella margarita x Citrange (Citrangequat), F. japonica x C. aurantiifolia (Limequat), C. maxima x C. aurantiifolia (Limelo), C. madurensis x C. aurantiifolia (Bigaraldin), C. maxima x C. sinensis (Orangelo), F. margarita x C. sinensis (Orangequat), C. nobilis (Clementine) x C. maxima (Clemelo), C. nobilis (King of Siam) x C. maxima (Siamelo), C. unshiu x C. maxima (Satsumelo), C. deliciosa x C. maxima (Tangelo), C. nobilis (King of Siam) x C. sinensis (Siamor), C. deliciosa x C. madurensis (Calarin), C. unshiu x C. madurensis (Calashu). C. aurantiifolia x F. marginata is immune (Reddy, 1997).
Other than Citrus species and their hybrids, most plants, except P. trifoliata, are not sufficiently susceptible to X. citri under natural conditions to warrant attention as hosts of the bacterium. Although the potential of these plants as natural hosts seems to be negligible, further investigation is necessary because no confirmative host surveys have been undertaken since the 1920s. Species names within the genus Citrus also merit some attention due to their inconsistent use by authors.
Plants other than Citrus spp.:
Unless otherwise stated, the following plants refer to Peltier and Frederich (1920, 1924) who defined susceptibility on the basis of artificial inoculation in the greenhouse (G) and/or in the field (F): Aeglopsis chevalieri (G), Atalantia ceylonica (G), Atalantia citrioides (G), Atalantia disticha (G) (Lee, 1918), Chalcas exotica (G), Casimiroa edulis (G, F), Chaetospermum glutinosum (G, F), Clausena lansium (G), Citropsis schweinfurthii (G), Eremocitrus glauca (G, F), Evodia latifolia (G), Evodia ridleyei (G), Feronia limonia [ Limonia acidissima ] (G), Feroniella lucida (G, F), Feroniella crassifolia (G), Fortunella hindsii (G, F), Fortunella japonica (G, F), Fortunella margarita (G, F), Hesperethusa crenulata (G, F), Lansium domesticum (G), Melicope triphylla (G), Microcitrus australasica (G, F), Microcitrus australasica var. sanguinea (G, F), Microcitrus australis (G, F), Microcitrus garrowayi (G, F), Paramignya monophylla (G), Paramignya longipedunculata (G) (Lee, 1918), Poncirus trifoliata (G, F), Xanthoxylum clava-herculis [ Zanthoxylum clava-herculis ] (G, F), Xanthoxylum fagara [ Zanthoxylum fagara ] (G, F) (Jehle, 1917). Atalantia ceylanica, A. monophylla, Microcitrus australis, Feronia limonia and Severinia buxifolia are immune (Reddy, 1997). In India, goat weed (Ageratum conyzoides) is reported to be a host (Pabitra et al., 1997) but confirmation is needed.
The following plants have also been reported as susceptible to X. citri, however, the original descriptions were either not confirmed (U) or contradict those of other authors (C): Aegle malmelos (C), Balsamocitrus paniculata (U), Feroniella obligata (U), Matthiola incana var. annua (U) and Toddalia asiatica (C).
Of the primary hosts listed, yuzu is highly resistant (Goto, 1992) and calamondins, Cleopatra mandarin and Sunki mandarin are immune (Reddy, 1997). Both Fortunella japonica and F. margarita are highly resistant (Goto, 1992).


Source: cabi.org
Description


As flowering specimens are very leafy and with a similar habit to many free-living plants, people who are not familiar with root hemi-parasites are unlikely to recognize that A. vogelii is indeed parasitic. Below ground, bright orange stems are attached to host roots by a spherical haustorium up to 2 cm in diameter. This is composed of a mass of host and parasite tissue and the orange adventitious roots of the parasite. Plants grow to 30-45 cm tall, often as a single stem but sometimes branching from near soil level. The stems and leaves, which can be 1.5 to 3.5 cm long by 0.3 to 1.5 cm wide, are conspicuously hairy. Leaf shape, particularly the nature and extent of toothing along the edge of the lamina, varies considerably. In parts of West Africa, leaf margins are almost entire, in central and southern Africa they may have two to five widely spaced teeth along each edge while in Kenya plants with five or six sharp teeth, each up to 3 mm long, have been collected. Flowers appear singly on a short stem in the axils of upper leaves or bracts. Up to 10 flowers may open on one day. The flower buds are enclosed in a densely hairy calyx whose five lobes each have a triangular tip with an obtuse apex. The tubular corolla is formed of five petals fused towards the base, so that the flower is bell-shaped when open. The corolla is 0.6 to 1 cm in diameter and somewhat longer than the calyx. The petals are pale yellow and may or may not have three deep red veins. Both types of flowers can be found in a group of plants. The anthers and filaments are glabrous. The flowers wither and remain covering the developing globose seed capsule which swells to approximately 5 mm in diameter at maturity. The dust-like seeds have a complex structure. An outer cell layer of the testa is modified into a cone or a 'trumpet-like' structure about 1 mm long within which the 'kernel' of the seed, measuring about 0.15 mm by 0.25 mm, is suspended. The surface of the seed coat is covered in indentations.

Impact

A. vogelii is an annual parasitic weed of legume crops, particularly cowpea and groundnut, in semi-arid areas of East, West, Central and Southern Africa. It is closely associated with cultivation, is occasionally found associated with weeds of fallows but rarely in natural vegetation. Copious seed production and a long-lived seed-bank allow the rapid build up of infestations when susceptible crop cultivars are planted. Tiny seeds are easily spread by wind, surface water flow or in crop seed. The genus Alectra is on the USDA Federal Noxious Weed list. Despite the similar life cycle to Striga species which are listed, and potential for crop damage, A. vogelii does not appear on Noxious weed lists in Australia. An assessment of its global invasive potential is given by Mohamed et al. (2006).

Hosts


Cowpea is the major crop host of A. vogelii throughout its range (Parker and Riches, 1993). Bambara, groundnuts, common bean, soyabean, mung bean, and tepary are also common hosts and there have been occasional reports of infestation of chickpea and runner bean. Pigeon pea is the only widely grown grain legume which is not parasitized. Although A. vogelii can attack the crops listed there is clear geographic variation in the host range in different regions of Africa. Host range tests (Riches et al., 1992), indicate that populations from Mali, Nigeria and Cameroon can attack groundnut and cowpea. Samples from eastern Botswana and northern areas of Northern Province, South Africa attack mung bean in addition to cowpea and groundnut. Populations sampled from Kenya, Malawi and eastern areas of Northern Province, South Africa, parasitize bambara as well as crops which are susceptible elsewhere. No association has been observed between morphological variation, largely in leaf shape, and host preference. Many other legumes are hosts including species such as lab lab and velvet bean which are often introduced as fodder or green manure crops in infested areas. A. vogelii has a wide host range and has been occasionally recorded as parasitic on non-legume weeds including Acanthospermum hispidum and Vernonia poskeana (Compositae), Euphorbia (Euphorbiaceae) and Hibiscus (Malvaceae) species in addition to common legume weeds including Indigofera and Tephrosia species.


Source: cabi.org
Description

Cuscuta species have a very distinct appearance, consisting mainly of leafless, glabrous, yellow or orange twining stems and tendrils, bearing inconspicuous scales in the place of leaves. In C. campestris, the yellow to pale orange true stems, about 0.3 mm in diameter, generally do not twine and attach to the host, but produce tendrils of similar appearance, arising opposite the scale leaves, which do form coils and haustoria (Dawson, 1984). The seedling has only a rudimentary root for anchorage, while the shoot circumnutates, i.e. swings round anti-clockwise about once per hour, until it makes contact with any stem or leaf, round which it will coil before growing on to make further contacts. The root and shoot below this initial attachment soon die, leaving no direct contact with the soil. Haustoria form on the inside of the coils and penetrate to the vascular bundles of susceptible hosts. Flowers, each about 2 mm across, occur in compact clusters 1-2 cm across. There is a calyx of 5 fused sepals with obtuse or somewhat acute lobes, and 5 corolla lobes, triangular, acute, often turned up at the end, equalling the length of the tube. Stamens alternate with the corolla lobes, each with a fringed scale below. The ovary is almost spherical with a pair of styles with globose tips. The capsule reaches 2-3 mm across when mature, with a depression between the two styles. The capsule does not dehisce and seeds remain on the plant long after maturity. Seeds are irregular in shape, rough-surfaced, about 1 mm across.

Symptons


The presence of Cuscuta is always obvious from the twining stems and tendrils. Symptoms of damage are not especially characteristic, but reflect the very powerful sink effect created by the haustoria, resulting in reduced vigour and, in particular, poor seed and fruit development.

Impact


The parasitic weed C. campestris is native to North America but has been introduced around the world and become a weed in many countries. It is by far the most important of the dodders, perhaps because of its wide host range. This ensures that there is a wide range of crop seeds that may be contaminated, and in which it may be introduced to new areas over both short and long distances. Once introduced it is almost certain that there will be suitable host plants on which it can thrive and be damaging, whether they are crops or wild species. Vegetative spread can be very rapid – up to 5 m in 2 months. It also has a wide tolerance of climatic conditions from warm temperate to sub-tropical and tropical.

Hosts


The host range of C. campestris is extremely wide. Several hundred crop and weed species have been listed as hosts, though some of these may only be acting as secondary hosts after the parasite is established on a more favoured primary host (e.g. Gaertner, 1950;Kuijt, 1969). Most are dicotyledonous, though the monocot onion can be seriously attacked. The plant is most important as a pest of lucerne and other legumes. Grasses sometimes appear to be acting as hosts but are not normally penetrated. The literature on host range is usefully reviewed by Cooke and Black (1987). Crops commonly parasitized, other than those listed in the table, include asparagus, chickpea, lentil, grape, citrus, melon, Lespedeza and flower crops including chrysanthemum. Not all hosts are consistently attacked, for example tomato is susceptible when young but becomes resistant with age (Gaertner, 1950).


Source: cabi.org
Description

O. cernua is a non-photosynthetic parasite producing erect, fleshy, leafless flowering stems 15-40 cm high bearing alternate scales less than 1 cm long. Although usually unbranched above ground, multiple stems sometimes arise from a single tubercle below ground. The plant is pale, completely lacking any chlorophyll. The base of the stem, below ground, is normally swollen and tuberous. The inflorescence, occupying up to half the length of the stems carries many acropetally developing flowers, arranged in spikes or racemes, each subtended by a bract 7-12 mm long (without the additional bracteoles present in O. ramosa). The calyx has four free segments, more-or-less bidentate, 7-12 mm long. The white corolla tube, 12-30 mm long, is inflated near the base, conspicuously down-curved, with narrow reflexed lips, up to 10 mm across. The tube is mainly white or pale while the lips are contrastingly blue or purple, without distinct venation. Filaments are inserted in the corolla tube, 4-6 mm above the base. A capsule develops up to 8-10 mm long and may contain several hundred seeds, each about 0.2 x 0.4 mm. A single plant carries 10-100 flowers and hence may produce over 100,000 seeds (Chater and Webb, 1972).

Recognition


It is possible to determine the level of O. cernua seeds in the soil by sieving the lighter, organic matter and the portion between 0.1 and 0.5 mm studied under a dissecting microscope for the presence of the characteristically sculpted seeds. Jacobsohn and Marcus (1988) have developed a method to check for the contamination of crop seed stocks which involves washing and sieving material a number of times. The presence of Orobanche seeds can be determined on the surface of the lower sieve, with the help of a dissection microscope.
Molecular techniques have also been developed for the detection of O. cumana seeds and the results of this assay can be expressed in terms of the number of O. cumana seeds per kilogram of crop seeds and can help decisions regarding crop seed lot utilisation and commercialisation (Dongo et al., 2012).

Symptons

O. cernua does not cause very distinctive symptoms but may cause some wilting, yellowing and necrosis of the foliage and a general weakening of the plant, with reduced fruit production. Hibberd et al. (1998) have shown that the damaging effect on Nicotiana tabacum (tobacco) is proportional to the weight of the parasite, while surprisingly, the carbon fixation by the host was increased by 20%. Under drought conditions there may be more serious reduction of crop growth.

Impact

O. cernua is an obligatory, non-photosynthetic root parasite which is native over a wide range across northeast Africa, southern Europe and western and southern Asia. In many of these areas it is a serious pest of Solanaceaeous crops such as Solanum lycopersicum (tomato) Nicotiana tabacum (tobacco) and S. melongena (aubergine) and occasionally S. tuberosum (potato). Species of Orobanche depend totally on their hosts for all nutrition and become an active sink for the host plant. This therefore results in a decrease in crop yield and as a result can have a major impact on the economy and livelihoods. Once established, the seed bank may last 10-20 years and there are no simple, economic control measures. Seeds of O. cernua are very small and inconspicuous and can be accidentally introduced into new areas as a contaminant of soil, seeds and machinery. There is potential for this species to invade many other areas of the world.

Hosts


The weedy form of O. cernua (var. desertorum), with which this data sheet is primarily concerned normally parasitises Solanaceae, especially Solanum lycopersicum (tomato) Nicotiana tabacum (tobacco), S. melongena (aubergine) and occasionally S. tuberosum (potato). In very dense infestations, there can be occasional attachment of O. cernua to species of Xanthium but it is possible that this occurred after stimulation of germination by an adjacent crop. Other varieties of O. cernua are usually recorded on Asteraceae, especially species of Artemisia but are also recorded on species of Galinsoga and Senecio. Helianthus annuus (sunflower) is usually attacked by the closely related species O. cumana rather but O. cernua has been recorded on sunflower in China (Daniel M. Joel, Newe Ya'ar Research Center, Israel, personal communication, 2016). Other crops which are attacked by O. cernua locally include Olea europaea (olive) in Jordan (Qasem, 2011), species of Capsicum (pepper) in Kenya, (Mwangi, 1999), Prunus armeniaca and P. persica in Jordan (Qasem, 2009), Cuminum cyminum (cumin) and Plantago ovata in Rajasthan, India (Maharshi, 2001).
A study on the mitochondrial activity in O. cernua from different hosts recorded this species on Petunia hybrida, Solanum nigrum and Datura metel (Singh, 2007).


Source: cabi.org
Description

O. ramosa produces leafless flowering stems, 15-20(-30) cm high, usually very branched, bearing alternate scales, less than 1 cm long. The plant is pale, completely lacking any chlorophyll. The base of the stem, below ground, is normally swollen and tuberous. The inflorescence, occupying approximately half the length of the stems carries many acropetally developing flowers, arranged in spikes or racemes, each subtended by a bract 6-10 mm long with two additional bracteoles, attached to the base of the calyx and of similar length. The calyx has 4(-5) lobes, more-or-less deeply divided into two segments, 6-8 mm long. The corolla, 10-20 mm long, is tubular, inflated at the base, with two approximately equal lips, the lower is 3-lobed. The corolla is whitish below and cream, blue or violet distally (occasionally all white). Filaments are inserted in the corolla tube, 3-6 mm above the base. A capsule develops up to 6-10 mm long and may contain several hundred seeds, each about 0.2 x 0.4 mm. A single plant carries ten to several hundred flowers and hence may produce up to a quarter million seeds. This description is from sources including Chater and Webb (1972), and O. ramosa is dealt with in some detail in Holm et al. (1997).

Symptons

O. ramosa causes no very distinctive symptoms but may cause some wilting, yellowing and necrosis of the foliage and a general weakening of the plant, with reduced fruit production.

Impact

O. ramosa does not spread rapidly or aggressively but its introduction in contaminated seed or soil can go undetected, and once introduced it can cause severe damage to important agricultural crops and prove very difficult to eradicate.

Hosts

O. ramosa has an especially wide host range, occurring on wild plants in the families Amaranthaceae, Chenopodiaceae, Euphorbiaceae, Capparidaceae, Labiatae [Lamiaceae], Linaceae, Malvaceae, Oxalidaceae, Plantaginaceae, Polygonaceae and Rubiaceae, as well as crops in Alliaceae [Liliaceae], Compositae [Asteraceae], Cannabinaceae, Cruciferae [Brassicaceae], Cucurbitaceae, Leguminosae [Fabaceae], Solanaceae, Rosaceae and Umbelliferae [Apiaceae] (Parker and Riches, 1993). See also Qasem and Foy (2007) for a recent study of host range in O. ramosa.


Source: cabi.org
Description

S. asiatica is not a conspicuous weed;it had spread to infest almost 200,000 hectares before being noticed in the USA. There is nothing about the shoot system of S. asiatica to suggest that it is a parasite. The height of the weed is variable, but rarely exceeds 30-40 cm, while some forms may be no more than a few centimetres high. Most other morphological characters are also variable. In vigorous plants there may be many branches, while small individuals or ecotypes may be unbranched. Length of the normal-looking green leaves may vary from 1 to 5 cm but leaf shape is generally narrowly lanceolate. Stem and leaves are sparsely covered in scabrid hairs.

Recognition


Where infestation is suspected, from previous history or from unexpected wilting symptoms, uprooting the crop can reveal the small white seedlings of S. asiatica on the roots, but the attachments are very fragile and gently washing the roots out of the soil will ensure a better chance of finding them.
A technique for detecting the seeds of S. asiatica as contaminants of crop seed is described by Berner et al. (1994). This involves sampling the bottom of sacks, elutriation of samples in turbulent flowing water and collection of seeds and other particles on a 90 µm mesh sieve. Striga seeds are then separated from heavier particles by suspension in a solution of potassium carbonate of specific gravity 1.4 in a separating column. Sound seeds collected at the interface are then transferred to a 60 µm mesh for counting.

Symptons


The symptoms of attack by S. asiatica may be apparent some time before the weed emerges, hence, the common name 'witchweed'. At an early stage, these symptoms are indistinguishable from those caused by drought, i.e. wilting and curling of the leaves, but they are strong indicators of S. asiatica if they occur when the soil is still moist. The infected plant may also show stunting from quite an early stage and pronounced scorching of the leaf borders and finally of the whole leaf area may occur at a later stage, hence, the common name 'fireweed' and equivalents in other languages.
As shoot growth is reduced, root growth is increased in plants infected by S. asiatica (Patterson, 1990).

Impact

S. asiatica is a hemiparasitic plant, native to Africa and Asia. In common with most other parasitic weeds, it is not especially invasive in natural vegetation, but is much feared in crop land where infestations can build up to ruinous levels, especially with repeated growing of susceptible cereal crops. For this reason it is included in almost all lists of noxious, prohibited plant species. It has recently been reported in Queensland, Australia. There is also evidence for its continuing spread and intensification within a number of countries in Africa in particular in rice in Tanzania and maize in Malawi. A study by Mohamed et al. (2006) suggests that on the basis of climatic data, there are many territories into which Striga species, including S. asiatica, could be introduced and thrive. Global warming could further increase this potential.

Hosts

S. asiatica is an obligate parasite and cannot develop without a suitable host plant. Apart from the major crops including sorghum, maize, pearl millet, finger millet, Panicum millets and rice, a wide range of wild hosts are parasitised. For the USA, these are listed by Nelson (1958), the most common being the weed Digitaria sanguinalis. There are many other wild hosts in Africa and Asia. Those recorded up to 1956 are listed in McGrath et al. (1957). Some further host species almost certainly include Andropogon gayanus, Axonopus compressus, Chrysopogon acicularis [ C. aciculatus ], Digitaria smutsii [ D. eriantha ], Eleusine indica, Elionurus elegans, Eragrostis malayana [ Eragrostis montana ], Ischaemum indicum [ Polytrias indica ], I. timorense, Microchloa indica, Rottboellia cochinchinensis, Sporobolus festivus and Stenotaphrum dimidiatum (synonym S. secundatum). Further hosts are listed by Cochrane and Press (1997). A number of broad-leaved hosts are recorded in McGrath et al. (1957) but occurrence on anything other than Poaceae is quite rare and some records may be suspect. Due to the very fragile connection between host and parasite it is often difficult, in a mixed grass community, to identify the host with any certainty.
There are distinct ecotypes of S. asiatica with different host specificity and each form may have quite limited host range. Botanga et al. (2002) describe a range of forms in Benin, including red- and yellow-flowered types with differing virulence on maize and sorghum but do not ascribe sub-specific names to these forms. Hence, there are many regions in Africa and Asia where the species occurs but is restricted to wild hosts and does not affect crops.

Biological Control
Organisms considered to have potential as biocontrol agents for S. asiatica and/or other Striga species have included the gall-weevil, Smicronyx spp. the agromyzid fly, Ophiomyia Strigalis, the moths, Eulocastra argentisparsa and Eulocastra undulata, the plume moth, Stenoptilodes taprobanes, the powdery mildew Sphaerotheca fuliginea and other fungi including Drechslera longirostrata, Phoma and Cercospora species (Greathead, 1984). Evans (1987) considered Cercospora strigae the most promising of the fungi. Several different species of Fusarium have been shown to have potential against both S. hermonthica and S. asiatica (Abbasher et al., 1995;1996). None of these organisms have yet been successfully utilised, but the possibilities for using Fusarium oxysporum are still considered promising (Beed et al., 2007). The strain Foxy 2, widely tested on S. hermonthica is confirmed also to be active against S. asiatica (Elzein et al., 2002). More virulent strains are now being tested along with a novel means of on-farm culturing and it is hoped there could be commercialisation before too long (Koltai, 2015). The only attempts to control S. hermonthica have been with the introduction of Smicronyx albovariegatus and Eulocastra argentisparsa from India into Ethiopia in 1974 and 1978, but there is no evidence that these organisms ever established.

Source: cabi.org
Description

Measurements

Symptons

The absence of symptoms does not mean absence of A. tritici (Thorne, 1949). Slight elevations occur on the upper leaf surface with indentations on the lower side. Other symptoms include wrinkling, twisting, curling of the margins towards the midrib, distortion, buckling, swelling and bulging. A tight spiral coil evolves, and dwarfing, loss of colour or a mottled, yellowed appearance and stem bending may also occur (Byars, 1920;Leukel, 1924). In severe infection, the entire above-ground plant is distorted to some degree and a disease problem is usually obvious.
Heads (spikes)
Wheat heads are reduced with glumes protruding at an abnormal angle exposing the galls to view. This does not occur in rye heads.
Galls
Young galls are short-thick, smooth, light to dark green, turning brown to black with age, 3.5-4.5 mm long and 2-3 mm wide. Rye galls are small, buff-coloured and longer than wide, 2-4.5 mm long by 1-2.5 mm wide (Byars, 1920;Leukel, 1924).

Impact

Anguina tritici, commonly referred to as wheat seed gall nematode, is the cause of ear-cockle disease. It was the first plant-parasitic nematode to be described in the scientific literature in 1743. Its host range includes wheat, triticale, rye, and related grasses;the primary host is wheat. Ear cockle in the past was reported in all major wheat growing areas. However, physical and mechanical methods for separating infected galls from seed have eradicated the nematode from the western hemisphere. It remains a problem in several countries in the Near and Middle East, the Asian Subcontinent and Eastern Europe, most likely due to poor awareness and lack of campaigns for establishing clean seed. A. tritici is on the U.S. Pests of Economic and Environmental Importance List, and on the ‘Harmful Organism Lists’ for Argentina, Brazil, Chile, Colombia, Ecuador, Egypt, Guatemala, Indonesia, Israel, Madagascar, Namibia, Nepal, New Zealand, Paraguay, Peru, South Africa, Taiwan, Thailand, Timor-Leste and Uruguay.

Hosts

A. tritici is highly specialized with a narrow host range. Significant multiplication only occurs on wheat or closely related plants. Many common grasses have been exposed to A. tritici;most have been shown to be non-hosts (Leukel, 1957).
Oat and Polypogon monococcum are poor hosts (Southey, 1972). A. tritici invades and multiplies in maize tissue, but does not complete its life cycle in this plant (Limber, 1976).
In addition to the hosts listed in the table, Alopecurus monspeliensis and Lolium temulentum (Dahiya and Bhatti, 1980), Holcus lanatus and Phleum pratensis (Filipjev and Schuurmans Stekhoven, 1941), and Triticum monococcum (Southey, 1972) are also reported as hosts of A. tritici.

Biological Control
There are few reports concerning biological control of A. tritici.<br>Host-Plant Resistance<br>A large number of plants have been evaluated for resistance to A. tritici over a period of more than 60 years. A few resistant plants have been found, such as the wheat cultivar Kanred (Leukel, 1924);however, resistance does not appear to be a viable solution to the problem of seed gall nematodes.

Source: cabi.org
Description

Measurements From Rice at Joydevpur, Bangladesh (Seshadri & Dasgupta, 1975) 15 females: L = 0.8-1.20 mm;a = 50-62;b = 6-9;c = 18-24;V = 78-80;stylet = 10-11 µm. 10 males: L = 0.7-1.18 mm;a = 40-55;b = 6-8;c = 19-26;T = 60-73;spicules = 16-21 µm;gubernaculum = 6-9 µm;stylet = 10 µm. 6 juveniles: L = 0.5-0.7 mm;a = 41-60;b = 6-9;c= 14-18;stylet = 8-10 µm. From Type Host and Locality (after Butler, 1913) females: L = 0.7-1.1 (0.9) mm;a = 47-58 (50);width= 15-22 (19 µm);b = 7.0 (?);c = 15-23 (20);V = 70-80;stylet = 9 or 10 µm. eggs = 80-88 µm x 16-20 µm. males: L = 0.6-1.1 mm;a = 36-47 (44);width = 14-19 µm;b = 7 (?);c = 18-23;stylet = 9 or 10 µm. After Goodey, 1932 females: L = 0.7-1.23 mm;a = 36-58;b = 7-8;c = 17-20;V = 80;stylet = 10 µm. males: L = 0.6-1.1 mm;a = 36-47;b = 6-7;c = 18-23;stylet = 10 µm. Description (after Seshadri and Dasgupta, 1975) Female Body slender, almost straight to slightly arcuate ventrally when relaxed by application of gentle heat. Cuticle with fine transverse striations;annules about 1 µm wide at mid-body. Lip region unstriated, not distinctly set off from the body, low, flattened, wider than high at lip base. Cephalic framework lightly sclerotized, hexaradiate, en-face view showing six lips of almost equal size. Lateral fields one-fourth of body width or slightly less, with 4 incisures, outer incisures more distinct than inner ones, extending almost to tip of tail. Deirids immediately posterior to the level of excretory pore. Phasmids close behind mid-part of tail, pore-like, difficult to see. Stylet moderately developed, conus attenuated, about 45% of total stylet length;knobs small but distinct, usually with posteriorly sloping anterior surfaces, rather amalgamated with one another, about 2 µm across. Procorpus cylindrical, narrows as it joins median oesophageal bulb, as long as 3-3.6 times body-width in that region. Median oesophageal bulb oval, with a distinct valvular apparatus anterior to the centre. Isthmus narrow, cylindrical, 1.5 to 1.9 times as long as procorpus;posterior oesophageal bulb usually clavate;27-34 µm long, slightly overlapping the intestine, mainly on the ventral side, with 3 distinct gland nuclei. Cardia absent. Nerve ring conspicuous, 21-35 µm behind median oesophageal bulb. Excretory pore 90-110 µm from anterior end, slightly anterior to beginning of posterior oesophageal bulb. Hemizonid 3-6 µm anterior to excretory pore. Vulva a transverse slit, vaginal tube somewhat oblique, reaching more than half-way across body. Spermatheca very elongated, packed with large, rounded sperms. Anterior ovary outstretched, oocytes in single row, rarely in double rows. Post-uterine sac collapsed, without sperms, 2.0-2.5 times as long as vulval body width, extending about 1/2 to 2/3 distance to anus. Tail conoid, 5.2 to 5.4 times the anal body width in length, tapering to a sharply pointed terminus resembling a mucro. Male As numerous as females. Body almost straight to slightly curved ventrally when fixed. Morphology similar to females. Caudal alae (bursa) present, narrow in some specimens, beginning opposite the proximal end of spicules, extending almost to tail tip. Spicules curved ventrally, simple;gubernaculum short, simple. Juveniles Similar to adults in gross morphology, oesophagus proportionally longer than in adults. Additional morphological and morphometric data was provided by Mian and Latif (1995). Type Host and Locality Oryza sativa, in Eastern Bengal (= Bangladesh).

Recognition


D. angustus feeds on tissue developing within the leaf sheath, so the youngest emerging leaf should be examined for symptoms in the field. Symptoms will develop within 1-3 weeks of infection, depending on the size and source of the initial inoculum. Infected plant residues, before flooding, provide primary infection sources in a field, whilst secondary and tertiary infection occurs from water with the onset of flooding.
Symptoms of low infection are difficult to detect: to accurately assess or confirm infection it is therefore necessary to sample tillers in the field. Tillers should be cut above the peduncle because nematodes are not found in the internodes below the growing point. 1-cm sections of the leaf sheath should be split longitudinally and placed in water for 24 h on a Baermann funnel placed in a bijou bottle or similar vessel. The nematodes will migrate into the water and can then be collected and counted. Such extracts may become foul within 24 h. For immediate examination of samples, leaf sheaths can be teased apart in water in a Petri dish to release nematodes and observe directly.


Source: cabi.org
Description


Eggs
The eggs of G. rostochiensis are always retained within the cyst body and no egg sacs are produced. The eggshell surface is smooth and no microvilli are present.
Length=101-104 µm;width="46"-48 µm;L/W ratio=2.1-2.5
Females
The females emerge from the root cortex about one month to six weeks after invasion by the second-stage juveniles. They are pure white initially, turning golden yellow on maturation. Mature females are approximately 500 µm in circumference without a cone. The cuticle of the female sometimes has a thin subcrystalline layer.
Stylet length=23 µm ± 1 µm;stylet base to dorsal oesophageal gland duct=6 µm ± 1 µm;head width at the base=5.2 µm ± 0.7 µm;head tip to median bulb=73 µm ± 14.6 µm;median bulb valve to excretory pore=65 µm ± 2.0 µm;head tip to excretory pore=145 µm ± 17 µm;mean diameter of the median bulb=30µm ± 3.0 µm;mean diameter of the vulval basin=22 µm ± 2.8 µm;vulval slit length=9.7 µm ± 2.0 µm;anus to vulval basin=60 µm ± 10 µm;number of cuticular ridges between the anus and vulva=21 ± 3.0.
The female head bears one to two annules and the neck region has numerous tubercules, which can be seen using a scanning electron microscope. The head skeleton is hexaradiate and weak. The stylet is divided equally in length between the conus and the shaft. An important diagnostic feature is the backward slope of the stylet knobs. The median bulb is large and circular and well developed. The large paired ovaries often displace the oesophageal glands. The excretory pore is well defined at the base of the neck. The posterior of the female, at the opposite pole to the neck and head, is referred to as the vulval basin and is contained within a rounded depression. The vulval slit is located in the centre of this region flanked on either side by papillae, which usually fill the translucent areas of cuticle in crescentic shape, from the slit to the edge of the fenestra. The anus is distinct and is often seen at the point in the cuticle where the 'V' shape tapers to an end. The number of cuticular ridges found in the area between the anus and the edge of the fenestra is counted as an aid to identification of Globodera species. The entire cuticle is covered in small subsurface punctations.
Cyst
Length without neck=445 µm ± 50 µm;width="382" µm ± 60 µm;neck length=104 µm ± 19 µm;mean fenestral diameter=19.0 µm ± 2.0 µm;anus to fenestra=66.5 µm ± 10.3 µm;Granek's ratio=3.6 ± 0.8.
Cysts contain the eggs, the progeny for the next generation, and are formed from the hardened dead cuticle of the female. Newly produced cysts may still show an intact vulval basin but older cysts, particularly those which have been in the soil for many seasons, will have lost all signs of their genitalia with only a hole in the cuticle to show the position of the fenestral basin.
Males
Length=0.89 -1.27 mm;width at excretory pore=28 µm ± 1.7 µm;head width at base=11.8 µm ± 0.6 µm;head length=7.0 µm ± 0.3 µm;stylet length=26 µm ± 1.0 µm;stylet base to dorsal oesophageal gland duct=5.3 µm ± 1.0 µm;head tip to median bulb valve=98.5 µm ± 7.4 µm;median bulb valve to excretory pore=74 µm ± 9µm;head tip to excretory pore=172 µm ± 12.0 µm;tail length=5.4 µm ± 1.0 µm;tail width at anus=13.5 µm ± 0.4 µm;spicule length=35.0 µm ± 3.0 µm;gubernaculum length=10.3 µm ± 1.5µm.
The male is vermiform in shape with a short tail and no bursa. On fixation, the body assumes a curved shape with the posterior region twisted at a 90 degree angle to the remainder of the body. There are four incisures in the mid-body i.e. three bands which terminate on the tail. The rounded head is offset and bears 6-7 annules. The head is strongly developed having a hexaradiate skeleton. The cephalids are located at body annules 2-4 and 6-9, respectively. The stylet is strong and has backward sloping knobs. The median bulb is well developed and has a large crescentic valve. The nerve ring is located around the oesophagus between the median bulb and the intestine. The hemizonid is found 2-3 annules anterior to the excretory pore and is itself two annules in length. The hemizonion is approximately nine body annules posterior to the excretory pore and is one annule in length. The single testis fills half the body cavity. The paired spicules are arcuate and end with single tips. The gubernaculum is around 10 µm in length and 2 µm in thickness and lies in a position dorsal to the spicules.
Juveniles
Body length=468 µm ± 100 µm;width at excretory pore=18 µm ± 0.6 µm;head length=4.6µm ± 0.6 µm;stylet length=22 µm ± 0.7 µm;head tip to median bulb valve=69 µm ± 2.0 µm;median bulb valve to excretory pore=31 µm ± 2.0 µm;head tip to excretory pore=100 µm ± 2.0 µm;tail length=44 µm ± 12 µm;tail width at anus=11.4 µm ± 0.6 µm;hyaline tail length=26.5 µm ± 2.0 µm.
The second-stage juvenile hatches from the egg, the first moult taking place within the egg. The juvenile, like the male, is vermiform with a rounded head and finely tapered tail. The hyaline portion of the tail represents about two thirds of its length. The lateral field has four incisures in the mid-body region reducing to three at the tail terminus and anterior end. The head is slightly offset and bears four to six annules. The head skeleton is well developed and hexaradiate in form. The cephalids are located at body annules 2-3 and 6-8, respectively. The stylet is strong, the conus being about 45% of the total length. The stylet knobs are an important diagnostic feature and typically slope backwards. The median bulb is well developed and elliptical in shape, having a large central valve. The nerve ring encircles the oesophagus between the median valve and the intestine. The hemizonion is about one body annule in width and is located five body annules posterior from the excretory pore. The hemizonid is around two body annules in width and is found just anterior to the excretory pore. The gonad primordium is four-celled and located at around 60% of the body length.
Other measurements can be found in Granek (1955), Spears (1968), Green (1971), Greet (1972), Golden and Ellington (1972), Hesling (1973, 1974), Mulvey (1973), Behrens (1975), Mulvey and Golden (1983), Othman et al. (1988) and Baldwin and Mundo-Ocampo (1991).

Recognition


Potato cyst nematodes, in common with other cyst nematodes, do not cause specific symptoms of infestation. Initially, crops will display patches of poor growth and these plants may show chlorosis and wilting. When the tubers are harvested there will be a yield loss and tubers will be smaller. To be confident that these symptoms are caused by potato cyst nematodes and to give an indication of population density, soil samples must be taken or the females or cysts must be observed directly on the host roots. Detection based on host plant symptoms and identification by morphological and molecular methods are detailed in EPPO (2009).
Surveys of the numbers and distribution of potato cyst nematode are prerequisites for making informed choices for their management. Samples taken within a field are either to check whether potato cyst nematode is present or not in the field for statutory purposes or to determine the extent of the infestation, which might include a determination as to what species is present.
At one time, it was considered that nematodes had a haphazard distribution in the field but this has been disproved. Aspects of the environment and ecological factors such as disease, predators and soil type favour aggregated distributions. Many models help to describe distributions, for example Taylor's Power Law (Taylor, 1961), Iwao's regression model (Allsopp, 1990) and others. However, geostatistical techniques may provide a more purposeful definition of the spatial distribution of nematodes. Although these techniques are young, 3-D maps can be generated to study nematode population levels more effectively. These methods have already proved useful in mapping other types of field related data (Chellemi et al., 1988) and have recently been applied to the distribution of potato cyst nematodes (Evans et al., 2003).

Symptons


Potato cyst nematodes, in common with other cyst nematodes, do not cause specific symptoms of infestation. Initially, crops will display patches of poor growth and plants in these patches may show chlorosis and wilting. When the tubers are harvested there will be a yield loss and tubers will be smaller. To be confident that these symptoms are caused by potato cyst nematodes and to give an indication of population density, soil samples must be taken or the females or cysts must be observed directly on the host roots. In heavily infested soils, plants have reduced root systems and often grow poorly due to nutrient deficiencies and to water stress. Plants may senesce prematurely as they are more susceptible to infection by fungi such as Verticillium spp. when heavily invaded by potato cyst nematodes.
Direct damage to roots and the yield of tubers
The infective second stage juveniles of both G. rostochiensis and G. pallida respond to environmental conditions when hatching. There is a short period of time for the second stage juvenile to locate a host root and begin the process of invasion, usually just behind the root tip. The juveniles then position themselves next to the stele within the root where, after a few hours, they will establish a feeding site (syncytium), which will become their nutrient source until their death. If a susceptible variety of potato is planted the plants will soon show signs of attack particularly when nematode density is high. In resistant plant varieties juveniles still hatch from the cyst and invade the plant roots, but they are unable successfully to establish a feeding site or syncytium. In this situation, males are more likely to be produced than females, as males have negligible nutrient requirements compared to females. Nevertheless, even resistant crops may show signs of attack.
The reduction in the yield of potato tubers, depending on the cultivar grown, is also related to or dependent on the plant's ability to tolerate the effects of nematode attack. The effects of potato cyst nematode on the plant include water stress and early senescence of the leaves. A heavily infested plant is unlikely to produce 100% ground cover with its reduced canopy of leaves. Many field studies have monitored the progression of ground cover by leaves and correlated the findings with yields (see Trudgill et al., 1998).

Impact

G. rostochiensis is a world wide pest of temperate areas, including both temperate countries and temperate regions of tropical countries, for example India’s Nigrilis region. Distribution is linked to that of the potato crop. Potato cyst nematode is considered to have originated from the Andes region of South America, from where it spread to Europe with potatoes. The ease with which it has been transported across continents proves what a resilient pest it is. The cyst form which adheres to host roots, stolons and tubers and to soil particles during transportation gives rise to new infestations where climate and food source are both available and favourable.

Hosts


The major hosts of G. rostochiensis are restricted to the Solanaceae, in particular potato, tomato and aubergine (Ellenby, 1945, 1954;Mai, 1951, 1952;Winslow, 1954;Stelter, 1957, 1959, 1987;Roberts and Stone, 1981;Sullivan et al., 2007). A number of weeds in the Solanaceae are also hosts.
In addition to the main hosts listed, the following plants are hosts of G. rostochiensis:
Datura tatula, D. ferox, Hyoscyamus niger, Lycopersicon aureum, L. glandulosum, L. hirsutum, L. esculentum peruvianum, L. pimpinellifolium, L. pyriforme, L. racemigerum, Nicotiana acuminata, Physalis longifolia, P. philadelphica, Physochlaina orientalis, Salpiglossis sp., Saracha jaltomata, Solanum acaule, S. aethiopicum, S. ajanhuiri, S. ajuscoense, S. alandiae, S. alatum, S.americanum, S. anomalocalyx, S. antipoviczii, S. armatum, S. ascasabii, S. auriculatum, S. asperum, S. aviculare, S. berthaultii, S. blodgettii, S. boergeri, S. brevidens, S. brevimucronatum, S. bukasovii, S. bulbocastanum, S. calcense, S. calcense × S. cardenasii, S. caldasii, S. canasense, S. capsicibaccatum, S. capsicoides, S. cardiophyllum, S. carolinense, S. chacoense, S. chaucha, S. chenopodioides, S. chloropetalum, S. citrillifolium, S. coeruleiflorum, S. commersonii, S. curtilobum, S. curtipes, S. demissum, S. demissum × S. tuberosum, S. dulcamara, S. durum, S. elaeagnifolium, S. ehrenbergii, S. famatinae, S. fraxinifolium, S. fructo-tecto, S. garciae, S. gibberulosum, S. giganteum, S. gigantophyllum, S. gilo, S. glaucophyllum, S. goniocalyx, S. gourlayi, S. gracile, S. heterophyllum, S. heterodoxum, S. hirtum, S. hispidum, S. indicum, S. integrifolium, S. intrusum, S. jamesii, S. jujuyense, S. juzepczukii, S. kesselbrenneri, S. kurtzianum, S. lanciforme, S. lapazense, S. lechnoviczii, S. leptostygma, S. ligustrinum, S. longipedicellatum, S. luteum, S. macolae, S. macrocarpon, S. maglia, S. malinchense, S. mamilliferum, S. marginatum, S. mauritianum, S. melongena, S. miniatum, S. mochiquense, S. multidissectum, S. muricatum, S. neocardenasii, S. nigrum, S. nitidibaccatum, S. ochroleucum, S. okadae, S. oplocense, S. ottonis, S. pampasense, S. parodii, S. penelli, S. photeinocarpum, S. phureja, S. pinnatum, S. pinnatisectum, S. platense, S. platypterum, S. polyacanthos, S. polyadenium, S. prinophyllum, S. quitoense, S. radicans, S. raphanifolium, S. rostratum, S. rybinii S. salamanii, S. saltense, S. sambucinum, S. sanctae-rosae, S. sarrachoides, S. scabrum, S. schenkii, S. schickii, S. semidemissum, S. simplicifolium, S. sinaicum, S. sisymbrifolium, S. sodomaeum, S. soukupii, S. sparsipilum, S. spegazzinii, S. stenotomum, S. stoloniferum, S. suaveolens, S. subandigenum, S. sucrense, S. tarijense, S.tenuifilamentum, S. tlaxcalense, S. tomentosum, S. toralopanum, S. triflorum, S. tuberosum ssp. andigena, S. tuberosum ssp. tuberosum, S. tuberosum 'Aquila', S. tuberosum 'Xenia N', S. utile, S. vallis-mexicae, S. vernei, S. verrucosum, S. villosum, S. violaceimarmoratum, S. wittmackii, S. wittonense, S. xanti, S. yabari and S. zuccagnianum.
Note Oxalis tuberose (Oca), has been extensively tested in host range tests by Sullivan et al. (2007) and has been declared a non-host on this basis.


Source: cabi.org
Description


The original description was made from a population that seriously damaged pacara earpod trees (Enterolobium contortisiliqum) on Hainan Island in China (Yang and Eisenback, 1983), following a preliminary (false) identification from perineal patterns of females that indicated the presence of Meloidogyne incognita. The morphological characters from female, male and second-stage juvenile stages, as published in the original description, are detailed below.

Recognition


Similar to other root-knot nematode species, M. enterolobii induces typical galls on the roots of infested plants. In case of severe attacks, extremely large and numerous galls can be found (Cetintas et al., 2007). Above-ground symptoms include stunted growth, wilting, leaf yellowing and deformation of plant organs. Overall, crop yield is reduced both qualitatively and quantitatively. In addition, M. enterolobii infestation may favour attacks of roots by secondary plant pathogens.
The presence of M. enterolobii in infested soil and plant material can de determined after extraction of the nematodes using conventional methods and microscopic examination. However, as morphological characters often overlap in root-knot nematode species, misidentification of species using morphology as the only criteria may occur. Alternatively, the use of biochemical and molecular tools, such as esterase profiling and DNA-based markers, has proven to be a good complement to provide reliable diagnostics in most cases.

Hosts

M. enterolobii is considered to be a highly polyphagous species, with a host range similar to that of Meloidogyne incognita (Yang and Eisenback, 1983). The most frequently recorded hosts include many vegetables, e.g., tomato, pepper and watermelon (Yang and Eisenback, 1983;Rammah and Hirschmann, 1988) but also guava (Gomes et al., 2011), ornamental plants (Brito et al., 2010) and weeds (Rich et al., 2009). Of particular concern is the ability of M. enterolobii to develop on crop genotypes carrying resistance to the major Meloidogyne species, among which are resistant cotton, sweet potato, tomatoes (Mi-1 gene), potato (Mh gene), soyabean (Mir1 gene), bell pepper (N gene), sweet pepper (Tabasco gene) and cowpea (R k gene) (Yang and Eisenback, 1983;Fargette and Braaksma, 1990;Berthou et al., 2003;Brito et al., 2007;Cetintas et al., 2008). Very few crop species have been recorded as non-hosts for M. enterolobii, including grapefruit, sour orange, garlic and peanut (Rodriguez et al., 2003;Brito et al., 2004).


Source: cabi.org
Description


Cells of E. amylovora are Gram negative rods, 0.3 x 1-3 µm in size, occur singly, in pairs and sometimes in short chains, and are motile by two to seven peritrichous flagella per cell (see Paulin, 2000, for review).
E. amylovora forms colonies of characteristic colour and colony formation on most culture media (Bereswill et al., 1998). Colonies are domed, circular, mucoid on sucrose nutrient agar (Billing et al., 1961);red to orange on MS medium (Miller and Schroth, 1972);white, circular, mucoid on KB medium (Paulin and Samson, 1973);smooth large, pulvinate, light blue opalescent with craters on CCT medium (Ishimaru and Klos, 1984);and yellow, highly mucoid or less mucoid on MM2Cu media (Bereswill et al., 1998).

Recognition


Water-soaked flowers, spurs, or shoot tips accompanied by ooze production, followed quickly by necrosis, are early symptoms of fire blight. These symptoms can be detected in an orchard or nursery by experienced observers, but may be overlooked by the inexperienced.
A suitable period for inspection is 3-5 weeks after the blossom period. Look for necrotic leaves and branches, withered blossoms, crooked shoot tips, and ooze. Ooze is more likely to be present in the morning when air humidity is high and host water potential is positive;later in the day when the air is dry, ooze may be shiny and glassy.
Cankers may form on branches and trunks at the junction between infected and healthy bark tissues;therefore, inspections may be needed every 5-7 days throughout the summer or until no new infections are observed.
In autumn, mummified fruits and leaves hanging on dead branches is an indication of fire blight. In winter, the debris helps in locating cankers since the darker bark associated with old infection can blend in with the dormant healthy bark, particularly on older trees.

Symptons


Fire blight's basic symptom is necrosis or death of tissues. Droplets of ooze on infected tissues are also an important symptom;they are the visible indication of the presence of fire blight bacteria. Except for minor differences, the symptoms of fire blight are basically the same on all host plants.
Infected blossoms initially become water-soaked and of a darker green as the bacteria invade new tissues. Within 5-30 plus days (commonly 5-10 days), the spurs begin to collapse, turning brown to black. Initial symptoms are often coincident with the accumulation of about 57 degree days, base 12.7°C, from the infection date (Steiner, 2000).
Infected shoots turn brown to black from the tip;shoots often bend near the tip to form a so-called 'shepherd-crook' shape. Shoots invaded from their base exhibit necrosis of basal leaves and the stem. Leaves and fruits may be invaded through petioles or stems or infected through wounds, resulting in discoloration followed by collapse of the leaves and fruit. During wet, humid weather, infected leaves and particularly the fruit often exude a milky, sticky liquid, or ooze containing bacteria.
From infected flowers and shoots, the bacteria may invade progressively larger branches, the trunk and even the rootstock. Infected bark on branches, scaffold limbs, trunk and rootstock turns darker than normal. When the outer bark is peeled away, the inner tissues are water-soaked often with reddish streaks when first invaded;later the tissues are dark brown to black. As disease progression slows, lesions become sunken and sometimes cracked at the margins, forming a canker.
Trees with rootstock blight may exhibit liquid bleeding from the crown at or just below the graft union in early summer. Water-soaked, reddish and necrotic tissues are visible when the outer bark is removed. Trees with infected rootstocks often exhibit yellow to red foliage about a month before normal autumn coloration. Rootstocks such as M.26, M.9 and relatives of M.9 often show these symptoms without evidence of infection in the trunk of the scion. Infection of M.7 and a few other rootstocks occurs following infection of suckers arising from the rootstocks;the infected suckers exhibit typical shoot blight symptoms. Many trees with rootstock blight will die in the first year after infection;the remaining rootstock-infected trees often die within 2-3 years.
Any plant tissues invaded by the bacteria can show ooze production on their surface. This exudate is a specific symptom of fire blight. Depending on weather conditions and on the time of the day, ooze may or may not be produced. It is most frequently observed early in the morning when the host water potential is positive. It may appear in different ways: droplets, threads or film on the plant's surface.

Impact


The long distance spread of fire blight is a rare event which in most cases seems to be the result of plants or plant tissues being moved across the oceans. Short distance spread is the result of the characteristics of the pathogen, especially its ability to produce an exudate (bacteria embedded in exopolysaccharides) which is easily transported by wind, rain, insects or birds. This is very efficient;once the pathogen has moved into a new territory it almost always colonizes and becomes established. This is accompanied by economic losses in regions where apple, pear or loquat are grown commercially;it might prevent the survival of local cultivars and could disrupt international trade. To date fire blight has colonized most of North America, Western Europe and most of the countries around the Mediterranean Sea as well as New Zealand. Outbreaks of fire blight are irregular and difficult to control.

Hosts

E. amylovora is a pathogen of plants in the family Rosaceae;most of the natural hosts are in the subfamily Maloideae (formerly Pomoideae), a few belong in the subfamilies Rosoideae and Amygdaloideae (Momol and Aldwinckle, 2000). Genera in the subfamily Spiraeoideae have been reported as hosts on the basis of artificial inoculation (van der Zwet and Keil, 1979).
Strains of E. amylovora isolated from one host are pathogenic on most other hosts. This was the case for strains isolated from natural infections on Prunus salicina in the USA (Mohan and Thomson, 1996) and on Prunus domestica and Rosa rugosa in southern Germany (Vanneste et al., 2002a). Rubus strains (see Taxonomy and Nomenclature) are host specific;they are pathogenic on brambles but not on apple and pear (Starr et al., 1951;Braun and Hildebrand, 2005). Also, a few Maloideae strains exhibit differential virulence on apple;for example, strain Ea273 was not pathogenic across the same range of apple cultivars and rootstocks as common strain E4001A (Norelli et al., 1984, 1986).
Within each group of susceptible host plants, species or cultivars may be found with a high level of resistance;such plants may show no, or limited, symptoms under natural conditions or even following artificial inoculation (Forsline and Aldwinckle, 2002;Luby et al., 2002). Lists of resistant cultivars are published for important crops (van der Zwet and Keil, 1979;Zeller, 1989;Thomas and Jones, 1992;Berger and Zeller, 1994;van der Zwet and Bell, 1995;Bellenot-Kapusta et al., 2002).
Wild Pyrus (P. amygdaliformis, P. syriaca) in southern Europe and in the Mediterranean area, Crataegus (C. oxyacantha [ C. laevigata ], C. monogyna) in northern and central Europe, and ornamentals (Pyracantha, Cotoneaster, Sorbus) throughout Europe are important sources of inoculum for apple and pear orchards.


Source: cabi.org
Description

H. flavescens is a c oarse perennial herb with thick fleshy rhizomes and erect, leafy p seudostems of 1-3 m in height. The leaves are sessile and have slightly pubescent sheaths. The ligule is 3-5 cm long and membranous. Leaf blades are elliptic-lanceolate or lanceolate, 20-50 cm long and 4-10 cm wide and abaxially (beneath) pubescent with attenuate base, membranous margins and a caudate-acuminate apex. Inflorescences are oblong spikes, 15-20 cm long and 3-6 cm wide;bracts are imbricate, oblong to ovate, 3-4.5 cm long and 2-4 cm wide, concave, 4- or 5-flowered. The bracteoles are tubular and membranous. Flowers are creamy-white to pale yellow or yellow-white in a cone like inflorescence, fragrant with yellow stamens. The calyx is 3.5-4 cm long, pubescent, approximately half the length of the corolla tube and almost as long as the bract. It is split on 1 side, apical margin entire. Corolla tube is 7-8.5 cm, long and slender. The lobes are linear, 3-3.5 cm long. The lateral staminodes are wider than the corolla lobes. The labellum is erect, creamy yellow with an orange patch at base, obcordate, longer than wide, and apex is 2-lobed. Filament is white to cream, subequaling labellum. Top of anther protruding slightly beyond lip. Ovary hairy. Stigma funnelform, margin bearded. Fruits are globose capsules 1-2 cm in diameter with three valves, containing numerous seeds but not seen in much of its invasive range.

Impact

A native of the Himalayas, H. flavescens has been introduced to many locations around the world as an ornamental and subsequently escaped cultivation to become a weed of significant economic importance in countries with favourable moist and warm climates. It threatens native forests in New Zealand, in La Réunion it outcompetes native plants and forms dense stands in wet areas such as ravine sides, roadsides, native forest margins and disturbed forests, and in Hawaii it tends to be confined to forest edges but also impacts negatively on the ecosystem. Its spread and dispersal is facilitated by vegetative regeneration of its dense rhizomes, which allows it to cover large areas of land and prevent the re-growth and establishment of native species, endangering rare and specialized plant communities. It is similar in its ecology and impacts to other invasive Hedychium spp., e.g. Hedychium coronarium and Hedychium gardnerianum.

Hosts

H. flavescens is not a weed of crops. It is an invasive species that threatens the environment, native communities and biodiversity.
Biology and Ecology
Top of page
Genetics
The chromosome number is reported to be 2 n=34.
Physiology and Phenology
H. flavescens, like its close relative, H. flavum, possesses large yellow inflorescences but can be distinguished from the latter by its hairier leaves and generally paler yellow flowers. The Zingiberoideae have a forced dormancy period during which all the above ground parts are shed and the plant overwinters as a thick, fleshy rhizome. Either just before or at the earliest signs of the wet season, individuals break dormancy with vegetative or reproductive shoots. Reproductive Biology
Spread in its invasive range is mainly by vegetative growth via rhizomes;however, in Hawaii some evidence exists that H. flavescens may be naturalizing by seed, though no fertile fruits have yet been found. Environmental Requirements
H. flavescens is a plant of the humid tropics, though being native to high altitudes, it can also tolerate cooler temperatures if in fully humid climates. It prefers areas with a mean annual rainfall of 1000-5000 mm, a mean annual temperature of 11-20ºC, and it can also tolerate frosts, though they may kill above-ground plant parts. H. flavescens requires medium to high soil fertility, and prefers to grow in open, light-filled environments which are warm and moist but will readily colonise semi and full shade under forest canopies. Altitude range in its native India is 1200-2000 m (Hooker, 1897;Mitra, 1958), 500-800 m in Sichuan, south-western China, below 2000 m Sri Lanka, and below 400 m in Hawaii but up to 2300 m where annual rainfall exceeds 1500 mm.
Climate
Top of page
Climate|Status|Description|Remark
Af - Tropical rainforest climate| Preferred
60mm precipitation per month
Am - Tropical monsoon climate| Preferred
Tropical monsoon climate (60mm precipitation driest month but (100 - [total annual precipitation(mm}/25]))
Cf - Warm temperate climate, wet all year| Preferred
Warm average temp. 10°C, Cold average temp. 0°C, wet all year
Air Temperature
Top of page
Parameter
Lower limit
Upper limit
Absolute minimum temperature (ºC)
0
-5
Mean annual temperature (ºC)
20
11
Mean maximum temperature of hottest month (ºC)
17
14
Mean minimum temperature of coldest month (ºC)
13
10
Rainfall
Top of page
Parameter|Lower limit|Upper limit|Description
Dry season duration|0|1|number of consecutive months with 40 mm rainfall
Mean annual rainfall|5000|1000|mm;lower/upper limits
Rainfall Regime
Top of page
Summer
Soil Tolerances
Top of page
Soil drainage
impeded
seasonally waterlogged
Soil texture
heavy
medium
Natural enemies
Top of page
Natural enemy|Type|Life stages|Specificity|References|Biological control in|Biological control on
Hypochniciellum ovoideum| Pathogen
not specific
Notes on Natural Enemies
Top of page
Due to its economic importance, the wide range of pests and diseases attacking cultivated ginger have been well researched. By contrast however, not much is known about the mycobiota and entomofauna of wild ginger species. Very few fungal pathogens had been reported on H. flavescens in its invasive range (Farr et al., 2008) although a strain of the soil-borne bacterium, Ralstonia solanacearum was isolated from Zingiber officinale (edible ginger) in Hawaii and caused no bacterial wilt in H. flavescens despite causing symptoms in H. gardnerianum and H. coronarium (Anderson and Gardner, 1999). The basidiomycete Leptosporomyces ovoideus was also recorded from H. flavescens in Hawaii (Farr et al., 2008).
Biological control options were subsequently investigated in New Zealand (Winks et al., 2007) following on from the research carried out in Hawaii. A survey of fungi, bacteria and invertebrates associated with H. flavescens (and H. gardnerianum) in New Zealand was carried out in 2006-07 for a national collective of regional councils and the Department of Conservation but no specialist agents were found. Furthermore, no isolates of R. solanacearum were found during the course of the surveys, even though it is recorded as present in New Zealand on other hosts, and it was concluded that the strain known to attack gingers was not established in New Zealand. Given the lack of specialist agents in New Zealand, recommendations were made that a classical control programme should be made, involving surveys in the native range of the wild ginger species of concern. A scoping survey to the Eastern Indian foothills of the Himalayas was carried out in 2008 by CABI scientists, sponsored by a consortium from Hawaii and New Zealand, and highlighted a large suite of damaging natural enemies associated with the Hedychium complex. Subsequent phases of the project have continued to consolidate and prioritise natural enemies for specificity studies, with the focus of the research being on H. gardnerianum, the most pernicious of the invasive complex.
A shoot borer (Conogethes puctiferalis) and a leaf roller (Udaspes folus) have been recorded from Hedychium sp. in India and several species of pathogens have been documented from Hedychium species including the basidiomycete, Lecanocybe lateralis Desjardin & E. Horak, from senescent leaves of H. flavescens (Indonesia) (Soares and Barreto, 2008) and Leptosporomyces ovoideus from H. flavescens in Hawaii (Gilbertson et al., 2002).


Source: cabi.org
Description

R. solanacearum is a Gram-negative bacterium with rod-shaped cells, 0.5-1.5 µm in length, with a single, polar flagellum. The positive staining reaction for poly-ß-hydroxybutyrate granules with Sudan Black B or Nile Blue distinguishes R. solanacearum from many other (phytopathogenic) Gram-negative bacterial species. Gram-negative rods with a polar tuft of flagella, non-fluorescent but diffusible brown pigment often produced. Polyhydroxybutyrate (PHB) is accumulated as cellular reserve and can be detected by Sudan Black staining on nutrient-rich media or the Nile Blue test, also in smears from infected tissues (Anonymous, 1998;2006) On the general nutrient media, virulent isolates of R. solanacearum develop pearly cream-white, flat, irregular and fluidal colonies often with characteristic whorls in the centre. Avirulent forms of R. solanacearum form small, round, non-fluidal, butyrous colonies which are entirely cream-white. On Kelman’s tetrazolium and SMSA media, the whorls are blood red in colour. Avirulent forms of R. solanacearum form small, round, non-fluidal, butyrous colonies which are entirely deep red.

Recognition


The bacterium may be obtained from infected tubers or stems for staining purposes if a small portion of tissue is pressed onto a clean glass slide. Potato tubers can be visually checked for internal symptoms by cutting. Suspect tubers should be diagnosed in the laboratory. Appropriate laboratory methods to detect the pathogen have been laid down in a harmonized EU-interim scheme for detection of the brown rot bacterium (Anon., 1997). These methods are based on earlier described indirect immunofluorescence antibody staining (IFAS). Standard samples of 200 tubers per 25 t of potatoes are taken (Janse, 1988;OEPP/ EPPO, 1990a;Anon., 1997, 1998, 2006). Recently a very effective selective medium has been described (Engelbrecht, 1994, and modified by Elphinstone et al., 1996), that can also be applied for detection in environmental samples such as surface water, soil and waste (Janse et al., 1998;Wenneker et al., 1999). ELISA and PCR, based on 16S rRNA targeted primers as well as fluorescent in-situ hybridization (FISH) using 16S and 23S rRNA-targeted probes have also been used.
Ralstonia syzygii, causal agent of Sumatra disease of clove (Syzygium) and the distinct Blood Disease Bacterium, causal agent of blood disease of banana in Indonesia, are closely related to R. solanacearum and cross-react in serological and DNA-based detection methods (Wullings et al., 1998;Thwaites et al., 1999).

Symptons


Potato
Foliage: the first visible symptom is a wilting of the leaves at the ends of the branches during the heat of the day with recovery at night. As the disease develops, a streaky brown discoloration of the stem may be observed on stems 2.5 cm or more above the soil line, and the leaves develop a bronze tint. Epinasty of the petioles may occur. Subsequently, plants fail to recover and die. A white, slimy mass of bacteria exudes from vascular bundles when broken or cut.
Tubers: external symptoms may or may not be visible, depending on the state of development of the disease. Bacterial ooze often emerges from the eyes and stem-end attachment of infected tubers. When this bacterial exudate dries, soil masses adhere to the tubers giving affected tubers a 'smutty' appearance. Cutting the diseased tuber will reveal browning and necrosis of the vascular ring and in adjacent tissues. A creamy fluid exudate usually appears spontaneously on the vascular ring of the cut surface.
Atypical symptoms on potato (necrotic spots on the epidermis), possibly caused after lenticel infection, have been described by Rodrigues-Neto et al. (1984).
Symptoms of brown rot may be readily distinguished with those of ring rot caused by Clavibacter michiganensis subsp. sepedonicus (EPPO/ CABI, 1997). R. solanacearum can be distinguished by the bacterial ooze that often emerges from cut stems and from the eyes and stem-end attachment of infected tubers. If cut tissue is placed in water, threads of ooze are exuded. Because such threads are not formed by other pathogens of potato, this test is of presumptive diagnostic value. For ring rot, tubers must be squeezed to press out yellowish dissolved vascular tissue and bacterial slime.
Tomato
The youngest leaves are the first to be affected and have a flaccid appearance, usually at the warmest time of day. Wilting of the whole plant may follow rapidly if environmental conditions are favourable for the pathogen. Under less favourable conditions, the disease develops slowly, stunting may occur and large numbers of adventitious roots are produced on the stem. The vascular tissues of the stem show a brown discoloration and drops of white or yellowish bacterial ooze may be released if the stem is cut (McCarter, 1991).
Tobacco
One of the distinctive symptoms is partial wilting and premature yellowing of leaves. Leaves on one side of the plant or even a half leaf may show wilting symptoms. This occurs because vascular infection may be restricted to limited sectors of stems and leaf petioles. In severe cases, leaves wilt rapidly without changing colour and stay attached to the stem. As in tomato, the vascular tissues show a brown discoloration when cut. The primary and secondary roots may become brown to black (Echandi, 1991).
Banana
On young and fast-growing plants, the youngest leaves turn pale green or yellow and collapse. Within a week all leaves may collapse. Young suckers may be blackened, stunted or twisted. The pseudostems show brown vascular discoloration (Hayward, 1983). Moko disease, caused by R. solanacearum, is easily confused with the disease caused by Fusarium oxysporum f.sp. cubense. A clear distinction is possible when fruits are affected - a brown and dry rot is only seen in Moko disease.
Teak
Seedling wilt manifests itself as yellowing of the mature lower leaves, which show scorching and browning of the tissue between the veins. The younger leaves and terminal shoot become flaccid and droop. Affected seedlings show either a gradual loss of leaf turgidity or sudden wilting. Seedling wilt becomes evident in the early hours of the day and gradually becomes more pronounced by midday, especially on sunny days. The wilted seedlings may partially recover during the afternoon and evening when temperatures fall, but wilting becomes more pronounced on successive days. The roots of affected seedlings exhibit a brownish-black discoloration. In advanced stages of disease, the tuberous portion of the root becomes discoloured and spongy. In due course, seedlings with pronounced wilt symptoms become completely desiccated.
In container nurseries, R. solanacearum infects the cotyledons of emerging seedlings causing greyish-brown, water-soaked lesions, which spread to the entire cotyledon and become necrotic. The infection spreads to the adjoining stem and root tissues and the affected seedlings rot and die. Collar rot appears in 1- to 4-month-old bare-root seedlings as greyish-brown, water-soaked lesions at the collar region of seedlings, just above the soil level. The lesions spread longitudinally on the stem, both above and below ground level, becoming sunken and necrotic. The younger leaves become flaccid and droop followed by leaf scorching and pronounced vascular wilt. In bare-root nurseries, wilt usually occurs in small patches affecting individuals or groups of seedlings, which expand as more seedlings succumb to the infection.
Infection of mature foliage begins as greyish-brown to greyish-black, irregular lesions that spread to the entire leaf lamina. Infection spreads to the petioles and stems.

Impact


The strains in the race 3 group are a select agent under the US Agricultural Bioterrorism Protection Act of 2002 (USDA, 2005). Peculiarly, the organism, if not yet already present in North America in pelargonium (Strider et al., 1981), was introduced with cuttings of this host by American companies producing these cuttings for their markets in countries like Kenya and Guatamala (Norman et al., 1999, 2009;Kim et al., 2002;Williamson et al., 2002;Williamson et al., 2002;O’ Hern, 2004). A similar situation led to introductions of the pathogen from Kenya into some northern European nurseries. Once the source (contaminated surface water) was recognized and proper control measures (use of deep soil water, disinfection of cutting producing premises and replacement of mother stock), the problem was solved and the disease in greenhouses eradicated (Janse et al., 2004);Similarly race 1 has been introduced into greenhouses with ornamental plants (rhizomes, cuttings or fully grown plants) such as Epipremnum, Anthurium, Curcuma spp. and Begonia eliator from tropical areas (Norman and Yuen, 1998, 1999;Janse et al., 2006;Janse, 2012). Introduction can and did occur from Costa Rica and the Caribbean, Indonesia, Thailand and South Africa. However, this idea of placing pathogens on bioterrorist list for unclear and perhaps industry-driven reasons and its effects, is strongly opposed in a recent publication from leading phytobacteriologists. This is because R. solanacearum is an endemic pathogen, causing endemic disease in most parts of its geographic occurrence, moreover normal quarantine regulations are already in place where the disease is not present or only sporadically and are thought to be more efficient and less damaging to trade and research than placing this pathogen on select agent lists and treating it as such (Young et al., 2008). Peculiarly, it has been used in the control of a real invasive species, the weed kahili ginger (Hedychium gardenarium) in tropical forests in Hawaii. This is not without risks because strains occurring on this weed host were thought to be non-virulent, but later appeared to be virulent on many edible and ornamental ginger species as well (Anderson and Gardner, 1999;Paret et al., 2008). The earlier mentioned tropical strains belonging to phylotype II/4 NPB could become an emerging problem not only in the Caribbean, but also to Southern Europe and North Africa where higher yearly temperatures prevail. Another threat for these countries could be strains belonging to race 1, biovar 1 (phylotype I) that have already been reported from field-grown potatoes in Portugal (Cruz et al., 2008).

Hosts

R. solanacearum as a species has an extremely wide host range, but different pathogenic varieties (races) within the species may show more restricted host ranges. Over 200 species, especially tropical and subtropical crops, are susceptible to one or other of the races of R. solanacearum. Worldwide, the most important are: tomato, tobacco, aubergine, potato, banana, plantain and Heliconia. Within the EPPO region, race 3 (see Biology and Ecology) with a limited host range including potato, tomato and the weed Solanum dulcamara, is considered to have potential for spread.
Other host crops are: Anthurium spp., groundnut, Capsicum annuum, cotton, rubber, sweet potato, cassava, castor bean and ginger.
Many weeds are alternative hosts of the pathogen. Solanum cinereum in Australia (Graham and Lloyd, 1978), Solanum nigrum and, in rare cases, Galinsoga parviflora, G. ciliata, Polygonum capitata, Portulaca oleracea (for example, in Nepal;Pradhanang and Elphinstone, 1996a) and Urtica dioica have been reported as weed hosts for race 3 (Wenneker et al., 1998). S. nigrum and S. dulcamara are primary wild hosts for race 3.
Lists of host records have been recorded (Kelman, 1953;Bradbury, 1986;Persley, 1986;Hayward, 1994a) but the original reports, gathered over many years, vary greatly in reliability. Few reference strains from reported host plants have been deposited in publicly accessible culture collections to support the authenticity of records.


Source: cabi.org
Description

D. invadens is a small, agile, slug species with a reputation for pugnacity towards other slugs. Size range is 25-35 mm. The body is cylindrical, narrowing to a short but strongly truncate keel at the tail. The mantle is moderately large but less so proportionately than in D. laeve, so that the tail part of the body is clearly longer than the mantle. In living specimens the mantle is transversely wrinkled in front as in D. laeve. The body colour is variable. In Mediterranean countries a pinkish flesh-coloured ground colour is common with a translucent cuticle and few if any darker spots. This form can also occur in northern Europe. In north-west Europe two forms predominate, these are slightly or considerably darker colour forms. The most common is mid gray and translucent with lighter mantle, through the cuticle of which the shell and pale internal organs can be seen even in the field. There is a marbling of tiny darker spots, but these are difficult to see with the naked eye. In hilly or exposed areas a darker form occurs, with mid to dark grey ground colour and contrasting pale mantle on which darker spotting is particularly obvious. The respiratory pore is white-rimmed, more clearly marked in darkly pigmented specimens. The sole in most specimens is translucent grey and paler than upper body pigments. Pedal and body mucus is colourless. Internally D. invadens has a rounded, compact penis with two fairly symmetrical, slightly elongate and inturned, ‘side pockets’ comprising the penial caecum and penial lobe (see Reise et al., 2011).

Impact

D. invadens is a small, agile slug that is native to the Mediterranean and has been recorded from at least 46 countries worldwide. Until 2011, this species was known as D. panormitanum but molecular work revealed that it comprised two distinct species. This species is similar in appearance to D. laeve and as a result, the exact distribution and impact of this species is unknown. This is a particular problem in countries such as the USA and Australia and probably also in South America. D. invadens is regarded as a significant pest of agricultural crops in New Zealand (Barker, 1999) but is highly likely to be damaging in many other countries as well. References to slug damage in agricultural crops by D. laeve are very likely to refer to D. invadens. In addition to this, D. invadens is an aggressive slug which may compete with native slugs, decreasing biodiversity.

Hosts

D. invadens is a generalist slug and has been recorded causing agricultural damage to crops. Examples of these species include;Asparagus officinalis, Avena sativa, Brassica napus, B. oleracea, B. rapa, Cucurbita maxima, C. pepo, Daucus carota, Franaria vesca, Hordeum vulgare, Lactuca sativa, Solanum tuberosum, Triticum aestivum and T. durum.

Biological Control
Phasmarhabditis hermaphrodita is a nematode parasite of slugs which, though most effective in controlling D. reticulatum and may also kill D. invadens (Speiser et al., 2001). However, this form of control is uneconomic for field crops at present.

Source: cabi.org
Description


The shell of G. kibweziensis is translucent white, and dorso-ventrally distorted due to allometric changes during shell ontogeny. The juvenile shell is discoidal dome-shaped;the adult shell more globose and with the axis of coiling at about 13° angle to the axis of the juvenile. When the adult shell is examined in apertural view, the juvenile whorls sit atop and displaced to one side by the broader last two whorls of the adult whorls. Adult whorls with broadly rounded periphery. Aperture rounded, without barriers, with somewhat thickened and slightly reflected margins;parietal callus well developed. Umbilicus a minute perforation.The protoconch is smooth. The teleconch whorls are delicately ribbed.

Impact

G. kibweziensis is a non-specific predatory snail, taking a number of other snail species as prey. The species is not widely recognized as invasive. While it has become widely distributed in the islands of the Pacific and Indian Oceans as a biological control agent against giant African snails, continues to be spread in at least some regions by human agencies, and is known to interact with some native mollusc species, G. kibweziensis has not been unequivocally confirmed as threatening ecosystems, habitats or species or having major economic consequence.
Predation on native snails in regions to which G. kibweziensis has been introduced is undoubtedly occurring. Concern about G. kibweziensis effects on native land snail communities has been expressed in a number of countries to which the species has been introduced as a biological control agent, but definitive evidence for such effects is presently lacking. The use of generalized predators in biological control programs has long been recognized as unsafe due to expected environmental impacts, not least adverse effects on non-target species.

Biological Control
<br>Most natural enemies of terrestrial gastropods have proved not to be host-specific and therefore are not amenable for use in control programmes where effects on non-target species are of concern. To date, no natural enemy specific to G. kibweziensis is known.

Source: cabi.org
Description

R. lauricola has been described in detail by Harrington et al. (2008). Optimal colony growth of R. lauricola occurs at 25°C, and cream-buff and smooth colonies develop on malt extract agar that are approximately 60 mm diameter after 10 days (Harrington et al., 2008). Colonies tend to become mucilaginous in their centres and these areas are dominated by budding yeast-like conidia. Colonies that develop from spores tend to be mucilaginous initially and after several days submerged hyphae develop at the colony margins. Conidiophores are hyaline, typically aseptate, and unbranched with lengths variable, usually ranging from 13-60 µm (range 13-120 µm) and 2 µm wide (range 1-2.5 µm). The conidia are hyaline and small, typically 3.5-4.5 µm (range 3.0-8.0 µm) x 1.5-2.0 µm (range 1.0-3.5 µm) and varying from elliptical to ovoid to globose (Harrington et al., 2008).

Recognition

The detection of laurel wilt in redbay and sassafras is usually straightforward with wilted and dead foliage occurring in some branches initially and eventually over the entire crowns of trees (Fraedrich et al., 2008). A black discolouration is observed in the sapwood of stems and branches. Initially, the discolouration is primarily evident in the outermost sapwood but as the disease progresses the discolouration will be observed through much of the cross-sectional area of the sapwood. Isolation of the pathogen from infected tissues on agar media is necessary to confirm the disease diagnosis. Frass tubes are typically observed on stems and branches of redbay and other species being attacked by X. glabratus, and frequently these are numerous after trees have wilted.

Symptons

R. lauricola moves rapidly in the xylem of trees (Fraedrich et al., 2015a) and disease symptoms are often observed in portions of redbay trees within two to four weeks after infection. The disease then spreads throughout the entire crown, and redbay trees typically wilt completely within 4 to 12 weeks following inoculation (Fraedrich et al., 2008;Mayfield et al., 2008b). Leaves of infected trees initially droop from loss of turgor and then turn a reddish-brown colour as they die. Some older leaves may initially become chlorotic as they are dying. Leaves on redbay and some other evergreen hosts do not abscise after dying and can be retained on branches for a year or more after the tree has died. A dark black discolouration is observed in the stem and branch sapwood of infected plants. The discolouration is initially observed in the outermost sapwood as localized streaks in the early stages of wilt, but over time the discolouration occurs more extensively throughout the cross-sectional area of the xylem tissue. Symptom development is similar in sassafras and other deciduous hosts except leaves are likely to drop as they die or soon after (Fraedrich et al., 2008;Fraedrich et al., 2015a). Sassafras leaves take on a reddish discolouration (Fraedrich et al., 2008) and pondberry leaves become very chlorotic and turn a bright yellow as they die (Best and Fraedrich, 2018).
The rate of development of the disease and subsequent symptoms in redbay plants depends greatly on their size and environmental factors, such as temperature and moisture conditions. The disease appears to progress relatively slow in trees infected late in the growing season, and trees with partial crown wilt on only a few branches can be found during the winter months. The disease progresses much more rapidly, and trees die quickly, during the spring and summer months when trees are actively transpiring and growing.
Symptom development in avocado is somewhat similar to that of redbay. The first symptom is the wilting of terminal leaves and the development of brown-to-black discolouration as they die (Ploetz et al., 2017a). Unlike redbay, leaves of avocado tend to abscise within 2 to 9 months following symptom development (Ploetz et al., 2017a). Apparently symptoms can be localized in avocado trees with the disease affecting some branches in portions of trees, and epicormic sprouting beneath the affected portions of trees can subsequently lead to the production of healthy branches (Ploetz et al., 2017a). The sapwood of infected trees develops a brown to black discolouration (Mayfield et al., 2008c).

Impact

Laurel wilt is responsible for the death of hundreds of millions of redbay (Persea borbonia sensu lato) trees throughout the southeastern USA, and the disease is also having significant effects on other species such as sassafras (Sassafras albidum) in natural ecosystems and avocado (Persea americana) in commercial production areas of south Florida. Laurel wilt is caused by the pathogen Raffaelea lauricola, a fungal symbiont of the redbay ambrosia beetle, Xyleborus glabratus. Thus far, the disease is confined to members of the Lauraceae that are native to the USA, or native to such places as the Caribbean, Central America and Europe and grown in the USA. The beetle and fungus are native to Asia and were likely introduced with untreated solid wood packing material at Port Wentworth, Georgia in the early 2000s. Since that time laurel wilt has spread rapidly in the coastal plains of the southeastern USA, spreading north into central North Carolina, as far west as Texas, and reaching the southernmost counties of Florida. Current models suggest that X. glabratus can tolerate temperature conditions that occur throughout much of the eastern USA, and so the disease threatens sassafras throughout much of this region. The disease poses a threat to lauraceous species indigenous to other areas of the Americas as well as Europe and Africa.

Hosts

Many members of the Lauraceae that are native to the southeastern USA appear to be highly susceptible to laurel wilt, although some have not been greatly impacted by the wilt for various reasons. A couple of species in the Lauraceae that are native to Florida appear to be somewhat resistant to the disease. Species indigenous to South East Asia appear to be mostly resistant to laurel wilt. A more complete assessment of what is known about the susceptibility of the individual species follows.
Persea borbonia (redbay) and P. palustris (swampbay) are very similar taxa with differentiating characteristics that are vague and not always reliable (Coker and Toten, 1945). Some have regarded the two taxa as the same species or varieties of a species (Radford et al., 1968;Little, 1979) while others consider them to be separate species (Shearman et al., 2018;Weakley 2015). Regardless, redbay and swampbay, historically treated by many as one species (Radford et al., 1968;Brendemuehl, 1990), appear to be equally susceptible to laurel wilt (Fraedrich et al., 2008), and are difficult to accurately distinguish under field conditions. Thus, redbay is treated in this database as a single species (i.e. P. borbonia sensu lato). Redbays are evergreen trees that occur in the coastal plain forests of the southeastern USA, and are a minor use hardwood and ecologically important in the forest ecosystems where they occur (Brendemuehl, 1990). Redbay has been affected by laurel wilt throughout much of its range with losses that are estimated into the hundreds of millions of trees (Hughes et al., 2017). The disease preferentially affects larger diameter trees (Fraedrich et al., 2008;Mayfield and Brownie, 2013) and throughout its range there is still high survivorship among smaller diameter redbay trees as well as sapling and seedlings (Cameron et al., 2015). The reason for this phenomenon is thought to be due to the preference of X. glabratus to attack larger diameter trees (Mayfield and Brownie, 2013) and not due to resistance in the smaller diameter plants (Fraedrich et al., 2008). Thus, although redbay trees have been devastated by laurel wilt in the southeastern USA, it does not appear that the species is in imminent danger of extinction. The long term survival of redbay in the southeastern USA will depend on the ability of X. glabratus to find and reproduce in smaller diameter redbays or other suitable hosts.
Sassafras albidum (sassafras) is a deciduous tree species that occurs in various forest types over much of the eastern half of the USA (Griggs, 1990;Randolph, 2017) and is a minor use hardwood (Harding et al., 1997;Cassen, 2007). Pathogenicity tests confirmed that sassafras is highly susceptible to laurel wilt (Fraedrich et al., 2008) and the disease has affected sassafras across the southeastern USA (Bates et al., 2013;Fraedrich et al., 2015a, Olatinwo et al., 2016). Recent studies indicate that X. glabratus can survive the low winter temperatures throughout much of the range of sassafras (Formby et al., 2018), however at this time, the northern most location of the disease is central North Carolina (Mayfield et al., 2019).
Persea americana (avocado) is a tropical evergreen tree that is native to Central America and the Caribbean. The species is cultivated for production of avocados in Florida and California in the USA, and is also grown in Mexico and many other countries. Three distinct races of avocado are recognized that include the Mexican, Guatemalan and West Indian. The West Indian and West Indian-Guatemalan hybrids are primarily cultivated for commercial production in Florida (Mayfield et al., 2008a). Some avocado cultivars are more susceptible to laurel wilt than others, and West Indian cultivars such as ‘Simmonds’ appear to be highly susceptible (Mayfield et al., 2008a;Ploetz et al., 2012a). The ‘Simmonds’ cultivar comprises approximately 35% of the avocado production in Florida (Ploetz et al., 2011b). The West Indian-Guatemalan hybrids are generally susceptible but less so than the West Indian cultivars, and Guatemalan x Mexican hybrids such as the ‘Hass’ cultivar appear to be among the most resistant (Mayfield et al., 2008a;Ploetz et al., 2012a). The ‘Hass’ cultivar accounts for 95% of all production in California (Ploetz et al., 2017a).
Persea humilus (silk bay) is another species for which the taxonomy is confused. Some would regard silk bay as a species (Nelson, 1994), while others regard this taxon as a variety of redbay (Persea borbonia var. humilus) (Wunderlin, 1998). Silk bay is a small evergreen tree that is native to the scrub forests of central Florida. Laurel wilt is currently affecting silk bay in forests, and its susceptibility to the disease has been confirmed through pathogenicity tests (Hughes et al., 2012).
Lindera melissifolia (pondberry) is a small, deciduous, clonal shrub that is extremely rare and listed as an endangered species in the USA. Pathogenicity tests have determined that pondberry is highly susceptible to laurel wilt, but the disease has only been observed once in this species under natural conditions (Fraedrich et al., 2011). Because of its small stem diameter, pondberry is not readily attacked by X. glabratus. However, because of the clonal nature of this species, when infections occur, the disease can spread rapidly through rhizomes and kill multiple ramets within a population (Best and Fraedrich, 2018).
Lindera benzoin (spicebush) is a common small, deciduous shrub species that is found in the southeastern USA, and in pathogenicity tests it proved to be highly susceptible to laurel wilt (Fraedrich et al., 2008). The disease has been documented only once naturally in spicebush (Fraedrich et al., 2016), and because of the small diameter of spicebush, it is not readily attacked by X. glabratus. Therefore, the disease does not appear to be a major threat to this species.
Litsea aestivalis (pondspice) is a relatively large (0.5-3 m tall) deciduous, multi-branched shrub that occurs in the southeastern USA. The species is rare and is listed as threatened. Pondspice is highly susceptible to laurel wilt (Fraedrich et al., 2011), but due to the small size of this species, it is not readily attacked by X. glabratus. Laurel wilt has been observed in pondspice in Georgia and South Carolina (Fraedrich et al., 2011) and Florida (Hughes et al., 2011).
Licaria trianda (pepperleaf sweetwood) is a rare, evergreen tree native to the lower, southeastern portion of Florida. The species is considered to be endangered. A pathogenicity study determined that pepperleaf sweetwood was susceptible to disease caused by R. lauricola. Leaves of infected seedlings developed chlorosis and abscised, and a brown discolouration was noted in the xylem of stems. However, seedlings did not die from the disease (Ploetz and Konkol, 2013).
Ocotea coriacea (lancewood) is a small, evergreen tree that is found at scattered locations in central to south Florida and elsewhere in Central America and the Caribbean. Saplings inoculated with R. lauricola develop discolouration in the xylem and occasionally dieback of the branches but saplings do not die (S Fraedrich, US Forest Service, Georgia, USA, unpublished data).
Umbellularia californica (California laurel) is a large evergreen tree species native to southwestern Oregon, and the Coastal Ranges and Sierra Nevada of California. In laboratory pathogenicity tests, R. lauricola -inoculated plants developed sapwood discolouration and branch dieback but plants did not die from wilt (Fraedrich, 2008). A subsequent study also found that California laurel was an excellent brood host for X. glabratus (Mayfield et al., 2013).
Laurus nobilus (bay laurel) is an evergreen tree or large shrub species that is native to the Mediterranean regions of Europe, Asia and Africa. The taxonomy of Laurus nobilis and a similar species, L. azorica, which is found in Madeira and the Canary Islands, is confused and in need of review (Arroyo-García et al., 2001). Laurus nobilus was introduced into the USA, where it has been cultivated as a culinary herb and valued as a landscape ornamental species. Laurel wilt has been observed in a landscape plant in Florida and susceptibility of the bay laurel to the disease was subsequently confirmed in pathogenicity tests (Hughes et al., 2014).
Persea indica (viñatigo) is an evergreen tree native to the maritime forests of the Canary Islands, Madeira and the Azores. Viñatigo has been used as an ornamental in Florida and California in the USA (Schuch et al., 1992), and the species has been shown to be susceptible to laurel wilt in field and laboratory experiments (Hughes et al., 2013).
Cinnamomum camphora (camphortree) is indigenous to China, Japan, Taiwan and other countries in eastern Asia. The species was introduced into the southeastern USA in the 1800s and was used for camphor production, but has escaped cultivation and is now naturalized in some forest types (Langeland et al., 2008). Camphortree appears to be highly resistant to laurel wilt. Reports of laurel wilt in camphortree are not known in Asia, and in the USA the disease rarely affects camphortree in areas where redbay populations have been decimated by laurel wilt. Dieback in camphortrees is occasionally observed in trees where laurel wilt is prevalent on redbay, and R. lauricola has been recovered from such trees (Smith et al., 2009;Fraedrich et al., 2015b). Single point inoculations of camphortree saplings with R. lauricola do not produce symptoms of laurel wilt or dieback under controlled conditions;however, multiple inoculations with R. lauricola have resulted in top dieback and mortality in saplings (Fraedrich et al., 2015b).
In addition, a study of the susceptibility of lauraceous species native to South East Asia, indicated that Cinnamomum osmophloeum, C. jensenianum, Machilus zuihoensis and M. thunbergii were also much more resistant to laurel wilt than species native to North America (Shih et al., 2018).


Source: cabi.org
Description

Sporangia are hyaline, ellipsoid or elongated-ovoid (length x width = 25-97 x 14-34 µm, mean 46-65 x 21-28 µm), sympodial, semipapillate, and deciduous, carried on a short stalk. They are produced readily on most media if plant material is included. They are also produced on V8 agar plates, although not consistently. Chlamydospores are large, round, hyaline or yellow-cinnamon depending on substrate. They can be terminal and intercalary or more rarely lateral, and are a good diagnostic feature, especially because of their size (20-91 µm, mean 46-60 µm). P. ramorum is a heterothallic, amphigynous species, and both mating types are known in nature but do not readily form sexual spores when artificially crossed. Measurements of mature gametangia are as follows: oogonial diameter, mean 30.5 µm, range 25-35 µm, oospore diameter, mean 25.5 µm, range 22.5-27.5 µm, antheridial width, mean 17.3 µm, antheridial length, mean 15.0 µm. Growth is optimal at 18-20¡C: a relatively slow grower. Hyphae are often extremely knobbly, although they lack swellings, and abundant septation can be observed, especially when producing chlamydospores. Mycelium is appressed, forming concentric growth rings more or less pronounced based on the type of media (Werres et al., 2001).

Symptons

P. ramorum causes three distinct types of disease with corresponding symptoms.;Stem Cankers (Rizzo et al., 2002a).;The cankers resemble those caused by other Phytophthora species. Discoloration can be seen in the inner bark, the cambium and within the first few sapwood rings. Discoloration is always associated with the cankers, but its intensity is extremely variable, ranging from dark-brown, almost black, lesions to slight discoloration of the infected tree tissue. Black zone lines are often, but not always, present at the edge of the cankers. Smaller tanoaks (Notholithocarpus densiflorus) tend not to have any zone lines. Most notably, P. ramorum cankers stop abruptly at the soil line, and there are few reports of root infection in tanoak. Viburnum is the only host in which root collar infection is common (Werres et al., 2001). Typical bleeding symptoms can be seen on the outside of the cankers. Bleeding is not necessarily associated with cracks or wounds, and tends to be rather viscous in consistency. A distinct fermentation smell (or alcoholic smell) emanates from bark seeps. Intensity and viscosity of bleeding changes with time. Older cankers may display a thin, brown-amber crust where seeps were originally present. Crown symptoms are often associated with expansion rate of cankers. Rapidly expanding cankers rapidly girdle the tree. In this case, there is no real crown decline, but once the tree has exhausted the resources accumulated in its aerial part, the whole crown browns. The entire foliage turns orange-brown and then becomes grey with time. The name 'sudden oak death' was coined because of the high frequency of rapidly declining trees. In the phase between girdling and apparent death of the crown, secondary processes are initiated. These include growth and fruiting of Annulohypoxylon thouarsianum, syn. Hypoxylon thouarsianum. A. thouarsianum will cause a mottled decay of portions of the sapwood and will fruit abundantly on the bark. Other secondary processes include attacks by bark and ambrosia beetles and acceleration of decay processes, at times with basidiocarps produced on trees which are still green.;When cankers are slow-growing, typical decline symptoms can be seen in the crown and include: chlorosis of the foliage, premature leaf abscission resulting in sparse crowns, and sometimes dieback of branches corresponding to portions of the stem affected by the canker. Epicormic shoots are often associated with both types of cankers (slow and fast). On oak species, most cankers are found within 1 m of the root collar, but cankers higher up on the stem and on major branches are not uncommon. Oak leaves, twigs, and juvenile plants are rarely infected. Tanoak cankers tend to be present throughout the vertical length of the tree and most trees have multiple cankers on them. Plants of all ages can be infected and killed. Leaves and twigs can also be infected. Foliar infection can precede or follow twig infection and it results in leaf spotting and a characteristic blackening of the main rib of the leaf, with lesions continuing into the petiole.;Leaf Blight and Branch Dieback (Rizzo et al., 2002b, Garbelotto et al., 2003).;Leaves develop lesions often associated with twig dieback. The primary infection court can be either in the twig or in the leaf. Cankers develop on branches. Symptoms on leaves develop rather rapidly and may result in death of the leaf. Rhododendron spp., Pieris spp. and Rhamnus spp. display these symptoms. In ericaceous hosts with small leaves (e.g. Vaccinium ovatum and Arctostaphylos spp.), foliar symptoms are not as pronounced. Leaf abscission and cane cankers are more common, resulting in the death of clumps of branches. Symptoms on coniferous hosts such as Douglas fir (Pseudotsuga menziesii) and Grand fir (Abies grandis) fall into this general category. In these two hosts, branch tips are typically affected. Branch tips, especially the last year's growth, are girdled and will wilt. Needles hang from the infected branch at first and then will drop, leaving a barren branch tip appearing similar to browse injury.;Leaf Spots, Blotches, and Scorches (Rizzo et al., 2002b, Garbelotto et al., 2003).;In some hosts, the disease affects leaves but not the twigs or branches. Lesions are normally associated with the accumulation of water on the leaf. These symptoms are in general rather nondescript. Lesions on Umbellularia californica are generally dark in colour, often at the leaf tip where water accumulates. Lesions are generally demarcated by an irregular margin, often followed by a chlorotic halo. Premature chlorosis of the entire leaf, followed by its abscission, is common in drier areas. Infection in Aesculus californica starts as light circular spots, coalescing into large blotches often affecting the whole leaf, and at times the petiole. In Acer macrophyllum, symptoms appear as a marginal leaf scorch. The scorch does not, at least initially, affect the whole leaf contour, and scorched portions are interrupted by healthy areas.

Hosts

Quercus rubra, Q. palustris, Pittosporum undulatum and many other species are regarded as potential hosts: for these species, inoculation experiments have been completed, confirming susceptibility, but no natural infection has been recorded to date (2003). A database of species tested for susceptibility is available at the Risk Analysis for Phytophthora ramorum website (http://rapra.csl.gov.uk/). More information on host range is given in the following references: Werres et al. (2001);Davidson et al. (2002a);Hansen and Sutton (2002);Linderman et al. (2002);Maloney et al. (2002);Parke et al. (2002);Rizzo et al. (2002a, b);Tooley and Englander (2002);Garbelotto et al. (2003);Huberli et al. (2003) and Kliejunas (2010). A host list is maintained by the USDA Animal and Plant Health Inspection Service (http://www.aphis.usda.gov/plant_health/plant_pest_info/pram/downloads/pd...). To date (2012) there are over 120 species listed. The California Oak Mortality Task Force (www.suddenoakdeath.org) also maintains a host list with photos of symptoms.


Source: cabi.org
Description

The following description is from Flora of China Editorial Committee (2016)

Impact

D. bicornis is an annual, sometimes perennial grass. It is listed as invasive in North America (Mexico), Central America (El Salvador, Guatemala, Honduras, Nicaragua, Panama), the Caribbean (Cuba), South America (Colombia, Ecuador) and Oceania (Nauru, USA-Hawaii) (Catasús Guerra, 2015;PIER, 2016). It is considered as a weed in cultivated fields (Quattrocchi, 2006;Dias et al., 2007;Duarte et al., 2009;Catasús Guerra, 2015;Ramírez S et al., 2015).

Hosts

D. bicornis is a weed that occurs in maize, rice, soyabean and sugar cane fields (Quattrocchi, 2006;Dias et al., 2007;Ramírez S et al., 2015). Plants of maize and rice have been reported as being affected by downy mildew disease caused by Sclerophthora rayssiae that was acquired from soil where seedlings of D. bicornis were previously growing (Chamswarng et al., 1976).


Source: cabi.org
Description

C. spectabilis is an erect herb 0.6-1.5 m tall. Branches terete, glabrous. Stipules ovate-triangular, approximately 1 cm. Leaves simple;petiole 2-8 mm;leaf blade oblanceolate to narrowly elliptic, 7-15 × 2-5 cm, thin, abaxially appressed silky pubescent, adaxially glabrous, base broadly cuneate, apex obtuse and mucronate. Racemes terminal, 20-30-flowered;bracts ovate-triangular, 7-10 mm. Pedicel 1-1.5 cm;bracteoles inserted at or apical to middle of pedicel, linear, approximately 1 mm. Calyx 2-lipped, 1.2-1.5 cm, glabrous;lobes broadly lanceolate-triangular, longer than tube. Corolla pale yellow;standard veined purplish red, suborbicular to oblong, 1-2 cm, base with 2 appendages, apex obtuse to retuse;wings obovate, approximately 2 cm;keel rounded about middle, with a fairly short and slightly incurved twisted beak beyond calyx. Legume broadly oblong, 2.5-3 × 1.5-2 cm, 20-30-seeded, shortly stipitate, glabrous. Seeds smooth, dark brown, 4.5 mm long (Flora of China Editorial Committee, 2015).

Impact

C. spectabilis is native to tropical Asia and has been widely introduced in many tropical countries around the world. It has escaped from cultivation and can now be found naturalized principally in open and disturbed sites. This species is a serious weed in agricultural land and natural habitats (Randall, 2012). The potential invasiveness of C. spectabilis is very high mainly because this species spreads predominantly as a contaminant in agricultural equipment, crop seeds, forages and hay (Maddox et al., 2011). In the United States, it is listed as a noxious weed in many Mid-South states (e.g., Arkansas), and it has spread rapidly throughout the Southeastern states where it is now considered an invasive species (Maddox et al., 2011;USDA-NRCS, 2015). C. spectabilis is also listed as invasive in Cuba, Australia, New Caledonia and many other islands in the Pacific Ocean (Oviedo Prieto et al., 2012;PIER, 2015;Weeds of Australia, 2015).

Hosts

C. spectabilis is a common weed in maize and soyabean plantations in the United States. It is also a weed in active and abandoned pastures (Maddox et al., 2011).


Source: cabi.org
Description

C. cardunculus is an erect perennial herb that can grow between 60 and 150 cm, but has been known to grow as tall as 2 m with a spread of 2 m (Weeds of Australia, 2016;Elzebroek and Wind, 2008). It has a large taproot that regenerates each year (Kelly and Pepper, 1996). The root can grow to the depth of 2 m (Parsons and Cuthbertson 2001). The stems are thick and rigid, which often branch in the upper parts, they are longitudinally ribbed and covered in a cotton down. The above-ground portion of the plant dies down each year, but off-shoots rise from the rootstock next growing season (Elzebroek and Wind, 2008).

Impact

C. cardunculus is an erect perennial herb, commonly known as cardoon or artichoke thistle. Native to southern Europe and North Africa, it has been widely introduced and is recognised as invasive in parts of Australia, the USA, Chile and Argentina. It can form dense monocultures, displacing native vegetation and degrading native plant communities. In California, it is categorized as a Most Invasive Wildland Pest Plant, category A-1, on the Californian Exotic Pest Plants of Greatest Ecological Concern. It can aggressively invade and disrupt natural habitats and has been described as a robust invasive plant that exhibits characteristics of the world’s worst weeds.

Hosts

C. cardunculus is known to be a significant agricultural pest, in particular pastoral activity (Weeds of Australia, 2016). Once established C. cardunculus can become the dominant vegetation in an area by monopolising light, moisture and nutrients from the soil. In Australia it has known to adversely affect pastures, and lucerne, by crop contamination. The prickly nature of the herb deters grazing sheep and cattle (Parsons and Cuthbertson, 2001). A thick infestation can also limit the movement of livestock (Thomsen et al., 1986).

Biological Control
<br>Biological control is not feasible as C. cardunculus has closely related cultivated species, Cynara scolymus and Cynara altilis. It is unlikely that any biological control would therefore be restricted to C. cardunculus (Thomsen et al., 1986).<br>However in the USA, the accidentally introduced artichoke fly attacks the flower head of C. cardunculus. It is not an approved biocontrol agent and does not significantly affect commercial C. scolymus crops. The fly’s affect on native thistles is still being studied, and the impact on C. cardunculus populations are not known (DiTomaso et al., 2013).

Source: cabi.org
Description

D. aegyptium is a grass, with characteristic 'bird's foot' digitate inflorescence, up to 50 cm tall.
Annual, never stoloniferous. Culms up to 50 cm tall, up to 5 noded, geniculately ascending, usually rooting from the lower nodes, thus giving the plants a pseudo-stoloniferous appearance, not rarely forming radiate mats, branched from the lower nodes;internodes cylindrical, glabrous, smooth, striate, exserted above, variable in length;nodes thickened and glabrous. Young shoots cylindrical or rounded. Leaf-sheaths keeled, up to 5 cm long, rather lax, striate, tuberculately hairy on the keel or quite glabrous;ligule membranous, about 1 mm long, ciliolate along the upper edge;leaf blades flat when mature, rolled when in bud, linear, tapering to a fine point, up to 20 cm long and 12 mm wide, with 3-5 primary nerves on either side of the midrib, glaucous, usually more or less densely tuberculately hairy along the margins and the keel, less conspicuously so on the adaxial surface towards the tip.
Inflorescence digitate, composed of 4-8 spreading spikes. Spikes 1.5-6 cm long, on maturity often somewhat recurved, greenish-yellow or pallid;rachis keeled, smooth near the base, scaberulous towards the apex, tip mucroniform and curved. Spikelets 4 mm long, strongly compressed, ovate, solitary, sessile, patent alternately left and right on the ventral side of the axis;dense, forming a very flat comb, usually 3-flowered;lower florets bisexual, the upper florets rudimentary;axis without terminal stipe. Lower glume 2 mm long and 2 mm wide, ovate in profile, 1-nerved, sharply keeled, keel scabrid;upper glume 2 mm long excluding the 1.5-2 mm-long awn, oblong in profile, 1-nerved, sharply keeled, keel scabrid. Rachilla slender. Lemmas 3-4 mm wide, the upper smaller in dimensions (but similar), folded about the keel which is scabrid, broadly ovate in profile, lateral nerves delicate and indistinct;uppermost lemma epaleate. Paleas about 3 mm long, 2-nerved, keels scabrid, dorsally concave, shortly bifid at the apex. Three anthers, pale-yellow, 0.3-0.5 mm long, anther cells somewhat remote, with a conspicuous connective. Caryopsis sub-triangular or sub-quadrate, laterally compressed, rugose, light-brown, apex truncate, never convex, remains of pericarp at times visible. (Fisher and Schweickerdt, 1941).

Recognition

D. aegyptium is usually identified initially by the characteristic 'bird's foot' arrangement of the inflorescence with 4-8 spreading spikes. It is sometimes found as seed during inspections of seed samples.

Impact

Producing large quantities of seeds, D. aegyptium is a pioneer grass that quickly colonizes disturbed areas with light sandy soils, often near to coasts or where water accumulates. It is a common component of weed floras throughout the tropics but is rarely reported as an aggressive weed on its own. It is not on federal or state noxious weed lists in the USA and is not recorded on the ISSG database but is recorded by PIER (2016) as invasive on a number of Pacific and American islands including French Polynesia Islands, Micronesia, the Northern Mariana Islands and Hawaii. It is also listed as invasive on islands in the Mediterranean, the USA, Mexico, Costa Rica, Puerto Rico, Virgin Islands and the Lesser Antilles (Vibrans, 2009;Florida Exotic Pest Plant Council, 2011;Chacón and Saborío, 2012;Burg et al., 2012;Rojas-Sandoval and Acevedo-Rodríguez, 2015;DAISIE, 2016;USDA-NRCS, 2016).

Hosts

D. aegyptium is a ubiquitous weed in many cropping systems around the world. Holm et al. (1977) classified the degree of importance of D. aegyptium on crops in different countries, in decreasing level of severity, as follows: a serious weed of cotton in Thailand;a principal weed of cotton in Australia, Kenya, Mozambique, Nigeria, Sudan, Tanzania, Uganda and USA, of sugarcane in India, the Philippines and Taiwan, of groundnuts in the Gambia and USA, of maize in Ghana and India and of rice in Sri Lanka and India;a common weed of rice in Indonesia, Nigeria and the Philippines, of coffee in Kenya and Tanzania and of tea in Taiwan and it occurs in bananas, pawpaws, cassava, citrus, sweet potatoes and millet in countries of Africa, Asia and Central America.
D. aegyptium has also been recorded in the weed flora of the following crops: aubergines in India;black gram (Vigna mungo) in Bangladesh and India;cassava in the Philippines;chickpeas in India;chillies (Capsicum) in India;cotton in Brazil, South China, India, Nepal, Thailand, USA and Zambia;cowpeas in India;finger millet (Eleusine coracana) in India;groundnuts in Bangladesh, Ghana, India, Senegal and USA;maize in India, Nigeria, Pakistan, Philippines and USA;jute in India;mint in India;mung beans (Vigna radiata) in India;okras in Nigeria;pawpaws in the Philippines;pearl millet (Pennisetum glaucum) in Burkina Faso, Mali and India;pigeon peas in India;potatoes in the Philippines;rice (transplanted) in India, Indonesia and Pakistan;rice (upland) in Cameroon, Gambia, India and Nigeria;sesame in India;sorghum in Australia, India;soyabeans in Ghana, India, Côte d'Ivoire, Pakistan, Senegal;sugarcane in India, Taiwan and Peru;sweet potatoes in the Philippines, Taiwan and USA;tobacco in India;wheat in Bangladesh and India;yams in India and the Philippines.


Source: cabi.org
Description

E. crus-galli is an annual grass, culms 30-200 cm, spreading, decumbent or stiffly erect;nodes usually glabrous or the lower nodes puberulent. Sheaths glabrous;ligules absent, ligule region sometimes pubescent;blades to 65 cm long, 5-30 mm wide, usually glabrous, occasionally sparsely hirsute. Panicles 5-25 cm, with few-many papillose-based hairs at or below the nodes of the primary axes, hairs sometimes longer than the spikelets;primary branches 1.5-10 cm, erect to spreading, longer branches with short, inconspicuous secondary branches, axes scabrous, sometimes also sparsely hispid, hairs to 5 mm, papillose-based. Spikelets 2.5-4 mm long, 1.1-2.3 mm wide, disarticulating at maturity. Upper glumes about as long as the spikelets;lower florets sterile;lower lemmas unawned to awned, sometimes varying within a branch, awns to 50 mm;lower paleas subequal to the lemmas;upper lemmas broadly ovate to elliptical, coriaceous portion rounded distally, passing abruptly into an early-withering, acuminate, membranous tip that is further demarcated from the coriaceous portion by a line of minute hairs (use 25× magnification);anthers 0.5-1 mm. Caryopses 1.3-2.2 mm long, 1-1.8 mm wide, ovoid or oblong, brownish (Michael, 2003).

Impact

E. crus-galli is a grass species included in the Global Compendium of Weeds (Randall, 2012) and which is considered one of the world’s worst weeds. This species has the capability to reduce crop yields and cause forage crops to fail by removing up to 80% of the available soil nitrogen. E. crus-galli is considered the world’s worst weed in rice paddies and has been also listed as a weed in at least other 36 crops throughout tropical and temperate regions of the world (Holm et al., 1991). The high levels of nitrates it accumulates can poison livestock. It also acts as a host for several mosaic virus diseases. E. crus-galli is also considered an environmental weed that has become invasive in natural grasslands, coastal forests and disturbed sites in Asia, Africa, Australia, Europe and America (FAO, 2014;USDA-ARS, 2014).

Hosts

E. crus-galli can be a very serious weed in rice, maize, soya bean, lucerne, vegetables, root crops, orchards and vineyards. It has been reported to be a serious weed of 36 crops (Holm et al., 1991), particularly rice, where its similar habit and appearance make it difficult to distinguish when young.


Source: cabi.org
Description

Floating perennial aquatic plant, typically rooted in mud. Plant height up to 100 cm tall. Vegetative stems elongate, developing to and growing at water surface. Flowering stems erect, 8–12 cm, glabrous, distal internode 2–10 cm. Leaves submerged, floating or emergent (or a combination of any two). Sessile leaves submersed, no petiole, alternate on elongate stem. Petiolate leaves emersed;stipule 7–13 cm, apex truncate;petiole never inflated, 11–25 cm;blade round, 7–16 × 2.3–16 cm. Inflorescence a spike or panicle, subtended by 2 reduced, dissimilar leaves. Spikes 7–50-flowered sometimes carrying more than 60 flowers (Gopal, 1987). Flower zygomorphic, spathes obovate, 3–6 cm;peduncle 1.9–15 cm, pubescent with orange hairs. Perianth blue or white, limb lobes obovate, 13–25 mm, margins erose, central distal lobe dark blue at base with yellow distal spot (Haynes, 1988);proximal stamens 15–29 mm, distal 6–20 mm;anthers 1.2–2.3 mm;style 3-lobed. Seeds develop from an anatropous ovule. The fruit contains 10–13-winged seeds (Flora of North America, 2009) 1.5-2.6 mm long, 0.3-0.9 mm wide (Sher, 2009). The roots extend into the substrate, which length varies greatly;5 cm in the younger portions of the stems but can reach up to 1 m in the older portions (Padial et al., 2009).

Impact

E. azurea is a rooted perennial aquatic plant with submersed and emersed leaves. Several taxa of this family have spread, as weeds or ornamentals (Barrett, 1978), outside the limits of their native range (Eckenwalder and Barrett, 1986). Eichhornia crassipes is the species best known for its invasiveness;it is one of the most troublesome weeds in the world (Gopal, 1987) and is declared a noxious weed in many countries, including in the USA and in two states in Australia. The status of E. crassipes (water hyacinth) as a weed has led to the subsequent designation of E. azurea and several species of Eichhornia as prohibited imports in various countries (USDA-NRCS, 2016;The State of New South Wales, 2009).
E. azurea was introduced into the USA from South America as an aquatic ornamental in the 1980s. It has occasionally escaped into local environments in the USA (Gopal, 1987) but has not become established as a weed there. According to historical records, E. azurea has been reported in southern Florida and more recently in Texas (TexasInvasives.org, 2016). It has also been reported in Japan but possibly as a temporary occurrence only (Kadono, 2004).
E. azurea is a weed with a widespread distribution in Brazil, where it often creates large floating mats which obstruct navigation and many other uses of aquatic resources. Reproduction is by seed and vegetatively. Dispersal is by whole plants, by water or by birds.


Source: cabi.org
Description

H. verticillata is a submerged, monoecious or dioecious perennial. Its stems are branched, about 1 mm thick and up to 3 m long;the internodes are 3 to 50 mm long. The sessile leaves are formed in whorls at the nodes;there are 3-8, sometimes up to 12 leaves in a whorl. The leaves are 7-40 mm long, linear to lanceolate, with a conspicuous midrib. They have sharply toothed margins and spines on the vein on the lower side of the leaves;a few teeth may also be formed on this vein. These leaf characteristics are commonly used to distinguish H. verticillata from similar submerged plants in the Hydrocharitaceae, like Egeria and Elodea spp.
The inflorescences are unisexual, arising from spathes situated in the leaf axils, each flower has three sepals and three petals. All six perianth parts are clear or translucent green (the sepals usually slightly reddish).The male spathe is about 1.5 mm long, solitary in the leaf axils, somewhat spiny. The female spathe is about 5 mm long, solitary in the leaf axils. There are three petals, three stamens and three styles. The ovary is cylindrical to narrowly conical and is enclosed in the base of a hypanthium;the style is as long as the hypanthium and there are three stigmas. For further information, see Cook et al. (1974) and Aston (1977).
The fruit is cylindrical, about 7 mm long and 1.5 mm wide. It contains 2-7 oblong-elliptic seeds. For further information, see Cook and Lüönd (1982);Swarbrick et al. (1981);and Yeo et al. (1984).

Impact

H. verticillata is a submerged fast-growing aquatic herb. It has a highly effective survival strategy that makes it one of the most troublesome aquatic weeds of water bodies in the world. It has the potential to alter fishery populations, cause shifts in zooplankton communities and affect water chemistry. It forms dense masses, outcompeting native plants and interfering with many uses of waterways. It is readily dispersed by movement of plant fragments and can produce up to 6,000 tubers per m 2. Tubers can remain viable for several days out of water or for over 4 years in undisturbed sediment. They are not impacted by most management activities, and a small percentage can sprout throughout the year making the species very difficult to manage or eradicate. It can be spread by water flow, waterfowl and recreational activities and is sold as an aquarium plant. Currently, this species is considered as one of the most aggressive invasive species in aquatic habitats. In the USA it has been listed as a Federal Noxious Weed since 1976, and is regarded as one of the worst invasive aquatic weed problems in Florida and much of the country. Its import is prohibited in Western Australia and Tasmania, and it is on the EPPO alert list.

Hosts

H. verticillata occurs in lowland irrigated and tidal ricefields in South-East Asia where it is most troublesome during the first half of the growth period of the crop.


Source: cabi.org
Description

I. cylindrica is a perennial grass which varies in height (30-150 cm). The culms (above-ground stems) are short, erect and arise from rhizomes (underground stems). The rhizomes are tough, white, commonly 1 m long but can be considerably more, are extensively branched and covered with papery scale leaves at the nodes. Roots are fibrous, emerging from the base of the culm and the nodes on the rhizome. Leaves are stiff, linear-lanceolate, up to 120 cm long and 4-18 mm wide, with a prominent, off-centre, whitish midrib, scabrid margin and pointed tip. The ligule is an inconspicuous membrane. The inflorescence is a white, spike-like panicle, terminal, fluffy, 5-20 cm long and up to 2.5 cm in diameter. Spikelets are numerous, 3.5-5.0 mm long, each surrounded by a basal ring of silky hairs 10 mm long. The grain is oblong, pointed, brown and 1-1.5 mm long.

Impact

I. cylindrica is a serious weed not only in crops but also in natural areas, causing serious economic and environmental damage. The ability of I. cylindrica to effectively compete for water and nutrients, spread and persist through the production of seeds and rhizomes that can survive a wide range of environmental conditions, and its allelopathic effects and pyrogenic nature, allow it to exclude native plant species and other desirable plants and dominate large areas of land.

Hosts

I. cylindrica is a weed of 35 crops worldwide (Holm et al., 1977) and 21 crops in West Africa (Chikoye et al., 2000). Some examples are cited in the list of hosts but most crops of the high rainfall tropics are likely to be affected by this weed.


Source: cabi.org
Description

T. domingensis is a rhizomatous perennial emergent wetland macrophyte. Ramets (culms) range from 1-6 m tall (Denny, 1985b) and consist of numerous slender, linear, distichous leaves with a sheathing base that emerge vertically from a central meristem. Ramets often produce a single, erect, monoecious flowering stem consisting of a staminate spike above a pistillate spike. At maturity, ramets can collapse from wind, or under their own weight (S Hall, University of Wisconsin, USA, personal communication, 2008). Rhizomes often measure several centimeters in diameter and produce abundant adventitious roots. Smith (1967, 2000) distinguished T. domingensis from similar species primarily on the basis of pistillate spike characters. T. domingensis is characterized by: pistillate bracteoles pale to light brown, slightly exceeding pistil hairs in mature spikes;pistil hair apices colorless to orange;stigmas linear to lanceolate, slightly exceeding bracteoles in mature spikes;pistillate spikes at anthesis cinnamon to light-brown, darkening slightly at maturity;monad pollen;staminate bracteoles (scales) straw to orange-brown colored;mucilage glands present on the adaxial surface of leaf sheathes and adjacent blades. Leaves are 6-18 mm wide, mature pistillate spikes are 13-26 mm wide, and the pistillate and staminate spikes are separated by a gap of 0-8 cm. Some quantitative macroscopic characters including spike width, gap length between pistillate and staminate spikes, and leaf width are useful, but are too variable for conclusive identification, which depends on the above microscopic floral characteristics. Finlayson et al. (1985) combined measurements of the gap between male and female inflorescences with the length and diameter of the female inflorescences to distinguish T. domingensis from T. orientalis in Australia.

Impact

T. domingensis can spread prolifically by rhizomes after seedlings establish in disturbed vegetation, often forming monotypes that reduce wetland plant and animal diversity. The species thrives under eutrophic conditions and artificially stabilized hydroperiods, but in undisturbed, low-nutrient wetlands, T. domingensis often grows sparsely and does not appear to reduce diversity. T. domingensis is economically important in many regions as a weaving material, but when invasive, the species can replace other valuable plant commodities. Short-term Typha control is provided by cutting, burning, or grazing, each followed by flooding, or herbicide, but re-growth from rhizomes and a vast soil seed-bank complicate eradication.

Hosts

T. domingensis can invade the margins of rice fields and lacustrine cornfields (Sykes 1981, cited in Finlayson et al., 1983;Hall, 2008).
Host Plants and Other Plants Affected
Top of page
Plant name|Family|Context
Oryza sativa|
Zea mays subsp. mays (sweetcorn)|Poaceae
Biology and Ecology
Top of page
Genetics
T. domingensis readily hybridizes with other sympatric species of Typha. T. domingensis x latifolia has mostly abortive pollen and low seed set, while T. angustifolia x domingensis (reported in France and California) is highly fertile and can form hybrid swarms (Geze, 1912, cited in Smith, 1987;Smith, 1967). T. domingensis, T. latifolia, and T. angustifolia share n=15 chromosomes (Smith, 1967). T. domingensis shows ecotypic variation for a number of traits, including salt tolerance, germination temperature, time of flowering, height, rhizome proliferation, and rhizome number (McNaughton, 1966). Because of the worldwide distribution of T. domingensis, quantitative data presented here will likely vary widely among regional ecotypes.
Reproductive Biology
T. domingensis is protogynous, self-compatible, and does not show apomixis (Smith, 1967). Pollen requires strong winds for dispersal, and T. latifolia pollen can travel distances of at least one km (Krattinger, 1975). Despite copious pollen production, self-pollination appears to exceed outcrossing even in dense stands of T. latifolia. Some populations of T. domingensis remain in anthesis for more than a month (McNaughton, 1966). Each inflorescence can produce 600,000 fruits, or 6-17 million seeds per m 2 depending on flowering ramet density, and plants established from seed can flower by the second year (Prunster, 1940, cited in Finlayson et al., 1983;Howard-Williams, 1975). Germination can occur year-round in many climates, given adequate moisture, although germination declines below 20 ° C (Finlayson et al., 1983). In the United States, southern populations germinated at a lower temperature (13 ° C) than their northern counterparts (McNaughton, 1966). Seeds germinate under moist or submerged conditions;in an extreme case, T. domingensis germinated under 80 cm of water and survived for 8 weeks (Nicol and Ganf, 2000). Salinity reduces germination, although limited germination can occur even at 20% salinity (Beare and Zedler, 1987). High salinity prevented T. domingensis from recruiting after a lake drawdown in Malawi (Howard-Williams, 1975). Exposure to light and hypoxia increase germination (Sifton, 1959), which is low under established vegetation (Finlayson et al., 1983). In natural areas not disturbed by humans, disturbance and herbivory by animals could facilitate seedling establishment of Typha seedlings (Svengsouk and Mitsch, 2001).
Lateral rhizomes can facilitate rapid vegetative expansion after seedling establishment. Individual T. latifolia clones can span 60 m (Krattinger, 1983), and T. domingensis can spread laterally at 3-10 m/year (Parsons and Cutherbertson, 1992;Fraga and Kvet, 1993). Rhizome production is stimulated by short days and cold temperatures (McNaughton, 1966).
Physiology and Phenology
In frost-free climates, T. domingensis can produce ramets (culms) year-round, although most emerge in summer and autumn, and do not survive longer than 10 months (Finlayson et al., 1983;Parsons and Cuthbertson, 1992). In a spring-fed wetland in central Mexico, T. domingensis growing in dense stands did not produce new ramets between May and October unless disturbed by leaf harvest (Hall et al., in press). Flowering ramets differentiate by spring, and become fertile by early summer. Grace and Harrison (1986) contend that high rhizome carbohydrate supplies promote Typha ramets to flower rather than to remain vegetative. Repetitive harvesting decreased rhizome starch reserves and flowering ramet density of T. domingensis, but drought stress could promote flowering (Hall, 2008). Carbohydrate dynamics have been studied for T. latifolia. Leaf biomass is at a maximum while rhizome biomass is minimized in late summer. By autumn, leaf carbohydrates have been translocated to rhizomes, biomass increases, and rhizome starch concentrations are maximized (Linde et al., 1976). For T. domingensis in Belize, leaf turnover averages 110 days (Rejmankova et al., 1996). Fraga and Kvet (1993) report that T. domingensis in Cuba had a net primary productivity of 1500 g/m 2 /year. Litterbag experiments showed only 50% decomposition after one year, and organic matter accumulated rapidly.
In flooded conditions, oxygen is conducted to Typha ’s underwater tissues via leaf aerenchyma cells (Sale and Wetzel, 1983), allowing T. domingensis to tolerate water 2 m deep (Finlayson et al., 1983). Flooded seedlings only produced additional ramets, however, when they reached the water surface (Nicol and Ganf 2000). T. domingensis is moderately salt-tolerant, and salinities of up to 5% should not impede vegetative growth or flowering. Salinity 5% prevents growth, and salinity 25% causes leaf mortality, although rhizomes re-sprout if salinity declines (Beare and Zedler, 1987). Freshwater inflows lasting 2 months allowed T. domingensis to invade California salt marshes. T. domingensis thrives in hot climates, and grows well in water at 30 ° C (Finlayson et al., 1983). Parsons and Cuthbertson (1992) reported maximum growth at 32 ° C, declining to 50% at 18 ° C. Typha spp. show a high tolerance for soil and water contaminated by heavy metals (McNaughton et al., 1974).
Nutrition
T. domingensis thrives under high nutrient loads and stable, prolonged, hydroperiods. In the Florida Everglades, T. domingensis invasion correlated with increased phosphorus and water levels, and muck-burning fires (Urban et al., 1993;Newman et al., 1998). Typha ’s limitation by phosphorus is supported by a comparison of soil and plant tissue samples from eutrophic and un-impacted areas of the Everglades (Koch and Reddy, 1992). T. domingensis also appeared limited by phosphorus in wetlands of Mexico’s Yucatan Peninsula and Belize (Rejmankova et al., 1996). In mesocosms, elevated nutrient levels and prolonged hydroperiods increased T. domingensis biomass and tissue phosphorus concentration relative to the co-occurring Cladium jamaicense (Newman et al., 1996). Substantial peat, nitrogen, and phosphorus accumulated where T. domingensis dominated nutrient-rich areas of the Everglades (Craft and Richardson, 1993). Seedlings produced more biomass, had a greater root/shoot ratio, and contained more phosphorous when grown in burned soil than in unburned or surface-burned soil in the Everglades, suggesting that soil-burning fires promote T. domingensis by releasing phosphorus (Smith and Newman, 2001). In low-nutrient areas of the Everglades, Typha is present but does not dominate (Davis, 1994).
Nitrogen and phosphorus appeared to co-limit the congener T. latifolia when it was grown in mesocosms, whereas in the field, T. latifolia increased along a gradient of increasing phosphorus (Svengsouk and Mitsch, 2001). T. x glauca required both nitrogen and phosphorus for growth in a greenhouse experiment, but adding a higher proportion of phosphorus stimulated growth regardless of nutrient concentration (Woo and Zedler, 2002).
Associations
In disturbed and eutrophic wetlands, T. domingensis tends to form monotypes. However, T. x glauca ’s invasive growth may be dependent on anthropogenic modifications (e.g. from dams, wastewater discharge, or irrigation canals). In little-disturbed wetlands where hydroperiods fluctuate seasonally, many genera co-occur with T. domingensis. In Australian wetlands, Baumea, Eleocharis, Gahnia, Melaleuca, Muehlenbeckia, and T. orientalis co-dominate with T. domingensis where water levels fluctuate (Finlayson et al., 1983;Nicol and Ganf, 2000). In Cuba, Bidens, Cyperus, Eleocharis, Hyparrenia, Panicum, and Sagittaria can co-occur with T. domingensis in shallow water, although T. domingensis often forms temporary monotypes in deeper water (Fraga and Kvet 1993). In this system, shrubs can replace Typha because of rapid organic matter accumulation;frequent fire might reduce litter and retard succession. In Africa’s Lake Victoria, T. domingensis is less abundant than the dominant Cyperus or Miscanthidium (Kansiime et al., 2007);in Lake Chad, Vossia, Cyperus, and Phragmites dominate, while T. domingensis is rare (Denny, 1985a). Thompson (1985) ranked T. domingensis as the third most-dominant African wetland plants, behind Phragmites australis and P. mauritianus. In Belize, T. domingensis normally dominates on clay soils with low salinity, while growing sparsely with dominant Eleocharis and Cladium on marl and sandy soil with higher salinity (Rejmankova et al., 1996). T. domingensis monotypes in this region may be relics of phosphorus-rich agricultural run-off. In Iran, T. domingensis and Schoenoplectus tabernaemontani co-dominate diverse wetlands (Karami et al., 2001). In a groundwater-fed wetland in central Mexico, harvesting T. domingensis increased species richness and the recruitment of uncommon species (Hall, 2008). Here, more than 40 species co-occurred with Typha and the co-dominant Schoenoplectus americanus.
Environmental Requirements
T. domingensis tolerates a broad climatic spectrum, growing between 40 ° latitude north and south under a variety of rainfall regimes (Smith, 2000). Although T. domingensis tolerates widely variable hydroperiods, it can decline during extended drawdowns, and grows best under flooded conditions (Rejmankova et al., 1996;Palma-Silva et al., 2005). Rainfall does not appear to limit wide-scale geographic distribution, because even in seasonally dry climates (e.g. central Mexico), T. domingensis can persist in isolated springs or on lakeshores. Seedlings can tolerate anaerobic conditions, but mature plants are intolerant of anaerobic conditions created when leaves are severed below water (Sale and Wetzel, 1983).
Climate
Top of page
Climate|Status|Description|Remark
Af - Tropical rainforest climate| Preferred
60mm precipitation per month
Am - Tropical monsoon climate| Preferred
Tropical monsoon climate (60mm precipitation driest month but (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer| Preferred
60mm precipitation driest month (in summer) and (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate| Preferred
60mm precipitation driest month (in winter) and (100 - [total annual precipitation{mm}/25])
BS - Steppe climate| Preferred
430mm and 860mm annual precipitation
BW - Desert climate| Preferred
430mm annual precipitation
C - Temperate/Mesothermal climate| Preferred
Average temp. of coldest month 0°C and 18°C, mean warmest month 10°C
Cf - Warm temperate climate, wet all year| Preferred
Warm average temp. 10°C, Cold average temp. 0°C, wet all year
Cs - Warm temperate climate with dry summer| Preferred
Warm average temp. 10°C, Cold average temp. 0°C, dry summers
Cw - Warm temperate climate with dry winter| Preferred
Warm temperate climate with dry winter (Warm average temp. 10°C, Cold average temp. 0°C, dry winters)
Latitude/Altitude Ranges
Top of page
Latitude North (°N)|Latitude South (°S)|Altitude Lower (m)|Altitude Upper (m)
40
40
0
0
Soil Tolerances
Top of page
Soil drainage
impeded
seasonally waterlogged
Soil reaction
acid
alkaline
neutral
Soil texture
heavy
light
medium
Special soil tolerances
infertile
other
saline
shallow
sodic
Notes on Natural Enemies
Top of page
Herbivory is common but variable. In Australia, kangaroos, rodents, and water birds lightly graze T. domingensis, while water buffalo can cause heavy damage (Finlayson et al., 1983). In Africa, large herbivores do not extensively feed on T. domingensis, despite its abundance (Howard-Williams and Gaudet 1985). In Costa Rica and elsewhere throughout Latin America, cattle heavily graze T. domingensis (McCoy et al., 1994). Muskrats (Ondatra zibethicus) can eliminate entire stands of Typha spp. through herbivory, at least in temperate climates (Kadlec et al., 2007). Barreto et al. (2000) mention a variety of fungal pathogens, although none have been extensively studied in the field. A variety of insects feed on T. latifolia and T. angustifolia. Lepidopteran larvae often inhabit inflorescences, while noctuid caterpillars and coleoptera attack leaves, stalks, and sometimes rhizomes (Grace and Harrison, 1986).
Means of Movement and Dispersal
Top of page
Natural Dispersal (Non-Biotic) Typha ’s tiny seeds (1 - 2 mm long) are contained in achenes attached to pistil hairs, and are often dispersed by the wind. Spikes do not shed fruits until they have dried (Krattinger, 1975), often delaying dispersal until many months after seed maturation. The entire female spike sometimes collapses in place, providing a floating platform for germination (Hall, 2008). Masses of achenes and hairs, and rhizomes, can disperse by floating on currents of water (Grace and Harrison 1986;Parsons and Cutherbertson, 1992).
Vector Transmission (Biotic)
When achenes are moistened, seeds are released, which have a pointed end that can become embedded in fish scales (Krattinger, 1975). Also, pistil hairs (with attached acenes) adhere to the clothing of fieldworkers, and could attach to animals as well (S Hall, University of Wisconsin, USA, personal communication, 2008). Mud with embedded seeds readily sticks to humans, livestock, birds, and agricultural implements (Parsons and Cuthbertson, 1992).
Intentional Introduction
Indigenous people in the Northwestern United States propagated T. latifolia using rhizome fragments (Turner and Peacock, 2005). Similar propagation of T. domingensis has not been documented.
Pathway Causes
Top of page
Cause|Notes|Long Distance|Local|References
Crop production|Seeds attach to mud on agricultural implements.| Yes
Parsons and Cuthbertson,
1992
Disturbance|Seedlings establish in disturbed vegetation.| Yes
Finlayson et al.,
1983
Hitchhiker|Achenes with hairs attach to humans and animals.| Yes
Yes
Parsons and Cuthbertson,
1992
Interbasin transfers|Achenes and rhizomes disperse with water currents.| Yes
Grace and Harrison,
1986;Parsons and Cuthbertson,
1992
Interconnected waterways|Achenes and rhizomes disperse with water currents.| Yes
Grace and Harrison,
1986;Parsons and Cuthbertson,
1992
Self-propelled|Achenes with hairs are wind-dispersed.| Yes
Krattinger,
1975
Pathway Vectors
Top of page
Vector|Notes|Long Distance|Local|References
Clothing, footwear and possessions|Achenes with hairs.| Yes
Parsons and Cuthbertson,
1992
Host and vector organisms|Achenes adhere to fish scales.| Yes
Krattinger,
1975
Water|Achenes with hairs, rhizomes.| Yes
Grace and Harrison,
1986;Parsons and Cuthbertson,
1992
Wind|Achenes with hairs.| Yes
Yes
Krattinger,
1975
Impact Summary
Top of page
Category|Impact
Economic/livelihood
Positive and negative
Environment (generally)
Positive and negative
Economic Impact
Top of page
T. domingensis can interfere with agriculture in wet areas. With the adoption of year-round rice cropping in Australia, T. domingensis invaded fields and decreased yields by 5% (Sykes 1981, cited in Finlayson et al., 1983). In central Mexico’s Lake Pátzcuaro, T. domingensis can invade low-lying cornfields. This species also tends to replace the bulrush Schoenoplectus californicus, a valuable species traditionally used to weave mats (Hall, 2008). In southern Mexico, T. domingensis invades wetlands used for horse pasture, and replaces valuable fodder (S Hall, University of Wisconsin, USA, personal communication, 2009). In lacustrine wetlands, T. domingensis can interfere with fishing and water transportation (Mitchell, 1985).


Source: cabi.org
Description

R. acetosella is perennial, reproducing by both creeping roots and seed. It has relatively shallow, extensive slender roots. Early growth is as basal rosettes of leaves. Leaves are 1-8 cm long, smooth, variable in shape but primarily consisting of three lobes, primary lobe is linear to egg-shaped terminating in a point;two secondary lobes appear at the base of the primary lobe and point outwards giving an arrowhead-shape appearance to the leaves which are sour in taste. It has long basal leaf stalks and short-stalked to sessile leaves on the upper stem;a membranous sheath (modified stipules) surrounds the stem above the leaf base. Multiple stems can appear from a single crown growing upright, 15-40 cm in height, slender, branching near the top to form a loose leafless panicle. Flowers are unisexual with male and female appearing on separate plants (dioecious). Males have six stamens on short filaments, females have three styles with branched stellate stigma. Flowers consist of three inner and three outer tepals, appearing red to yellowish, borne on raceme near the top of the stem. Flower stalks are jointed close to the flower. Seeds are three sided (achenes), ca. 1.5 mm in length, shiny reddish brown in colour. A reddish brown hull often adheres to the seed and is rough in texture (Buchholtz et al., 1954;Hitchcock and Cronquist, 1981;Gleason and Cronquist, 1991;Pojar and MacKinnon, 1994;Douglas et al., 1999).

Impact

Holm et al. (1997) listed Rumex acetosella as one of the world’s worst weeds, infesting 45 different crops in 70 countries. In 1891, the government of New South Wales pronounced R. acetosella to be one of the worst weeds introduced into Australia (Holm et al., 1997). Although R. acetosella is not shade tolerant, it still may be competitive in forage situations where grazing opens up the canopy (Leege et al., 1981). Its ability to recover quickly from grazing or clipping impacts also aids in its persistence in grassland and pasture habitats (Val and Crawley, 2004). Another aspect increasing the invasiveness of R. acetosella is its relatively large seedbank (Frankton and Mulligan, 1987).

Hosts

R. acetosella has been listed among the world’s worst weeds, infesting 45 different crops in 70 countries (Holm et al., 1997). It is a serious pest of lowbush blueberry (Vaccinium angustifolium) in Eastern Canada (McCully et al., 1991;Stopps et al., 2011). R. acetosella impacts blueberry yield via reduced floral bud numbers that result in considerably lower yields (Kennedy et al., 2010).

Biological Control
<br>Biological control has not been attempted for R. acetosella;neither have potential biological control agents been clearly identified (Stopps et al., 2011).

Source: cabi.org
Description

S. oleraceus is an annual and sometimes biennial herb, 40-150 cm tall, containing white latex in all plant parts. The taproot is upright with many branches, especially near the soil surface. Stem below synflorescence simple or branched, glabrous. Basal and lower stem leaves with basal portion petiole-like and attenuate, mostly smaller than middle stem leaves, otherwise similar. Middle and upper stem leaves extremely variable, elliptic, oblanceolate, or lanceolate, 6-20 × 2-9 cm, almost entire to ± irregularly, soft, glabrous, adaxially dull green, base auriculately clasping with auricles usually acutely prostrate, margin ± coarsely spinulosely dentate, apex acute;lateral lobes triangular to elliptic, usually recurved, apex acute to acuminate;terminal lobe larger than others, broadly triangular, broadly hastate, or obovate-cordate. Synflorescence shortly corymbiform or racemiform, with few to several capitula. The flower-head has a green involucre consisting of 27-35 lance-shaped bracts, 10-13 mm long and hairy while young. Each flower-head contains 80-250 ligulate flowers which are longer than the involucre. The flowers are yellow and the ligule is about as long as the corolla tub. Achenes are brown, 2.5-3.75 x 0.7-1 mm, oblanceolate, and transversely tuberculate-rugose. Thistledown is white and persistent. One plant may produce 4000-6000 seeds or more (Nyárády, 1965;Anghel et al., 1972;Boulos, 1976;Hutchinson et al., 1984;Ciocârlan, 1990).

Impact

S. oleraceus is a common seed crop contaminant and has been carried either deliberately or accidentally by humans to almost every corner of the earth, where it invades mainly open and disturbed areas. It grows in a wide variety of environments on a wide range of substrates – roadsides, cultivated land, gardens, construction sites, sand dunes, logged or burned areas, on walls, mountain slopes, and near water. Once introduced to a new area the plants spread quickly because they grow and flower quickly and produce copious wind- and bird-dispersed seeds that germinate quickly in large numbers. They invade many cropped areas, especially among vegetable and winter crops. They are almost perfect ‘designer weeds’. Additionally, this species has small light seeds which are easily dispersed by wind and water.

Hosts

S. oleraceus may occur as a weed in annual or perennial crops, particularly those which are widely-spaced or have a longer vegetation period, such as Helianthus annuus, Nicotiana tabacum, Arachis hypogaea, Phaseolus vulgaris and Citrullus lanatus. S. oleraceus competes with cultivated plants during fructification, and thus has a detrimental effect on yield (Holm et al., 1977). S. oleraceus grows well in optimally interspaced maize crops (Lorenzoni, 1963).

Biological Control
CSIRO (2007) in Australia has been exploring the possibility of biological control of this weed and has so far identified a rust fungus Miyagia pseudosphaeria, Aceria thalgi and the potential mycoherbicide pathogen, Aschochyta sonchi. The possibility of biological control had apparently been explored earlier in Canada (ISSG, 2014)

Source: cabi.org
Description

B. sylvaticum is a cespitose perennial bunchgrass that is sometimes very weakly rhizomatous. It ranges in height from a few centimeters up to about 200 cm. Sheaths are open and the nodes are typically pubescent. The leaf blades are bright green and remain green throughout the summer, even in dry Mediterranean climates (BA Roy, University of Oregon, USA, personal observation, 2009). The blades are 4-15 mm wide, flat and lax, with variable pubescence. Ligules are variable in size (1-6 mm) and are generally pubescent and ciliate. Plant size and pubescence depend both on habitat (Shouliang and Phillips, 2006) and genotype (Davies and Long, 1991). Racemes are nodding with an average of 9 spikelets, each with 3-24 florets. Lemma awns are 7-15 mm. Excellent full descriptions are published in the Flora of North America (Piep, 2003) and Flora of China (Shouliang and Phillips, 2006), both of which can also be found on line at www.efloras.org/index.aspx.

Recognition

For a grass, B. sylvaticum is relatively easy for botanists to identify because it grows in the shade of the forest (and often along trails, streams and rivers) and is quite pretty: it stays a bright vibrant green all season long, and has broad lax leaves and nodding inflorescences. Nonetheless, for identification it is best to involve a trained botanist as there are a couple of native forest grasses in North America with which it could be confused (for example, Bromus vulgaris, and possibly Melica subulata, Elymus glaucus and Bromus carinatus). Excellent identification information can be found at Piep (2003) and Shouliang and Phillips (2006).

Impact

B. sylvaticum is a bunchgrass naturally occurring in old world temperate forests and temperate zones of tropical Asian mountains. Its extensive native range includes most of Eurasia (e.g. Europe, Russia, China, Japan, India, Indonesia) as well as the Middle East (e.g. Lebanon, Syria, Iran) and North Africa (e.g. Algeria, Eritrea). It is invasive in North America (Piep, 2003), South America (Zuloaga et al., 1994), New Zealand (Edgar and Connor, 2000), and Australia (IBIS, 2009). It is shade tolerant (Murchie and Horton, 1998), spreads rapidly by seeds (Petersen and Philipp, 2001), has a persistent seed bank (Donelan and Thompson, 1980;Buckley et al., 1997) and is long-lived (Haeggström and Skytén, 1996). It forms monocultures and crowds out native plants and rare butterflies (Kaye and Blakeley-Smith, 2006;Severns and Warren, 2008). Furthermore, grasses significantly reduce recruitment of conifers (Powell et al., 1994;Lehmkuhl, 2002;Kruse et al., 2004). It is on noxious weed lists for three USA States: California, Oregon and Washington (CDFA, 2009;NWCB, 2009;ODA, 2009).

Hosts

The Pacific Northwest is world renowned for its timber production from conifers. It has not been established through a controlled study that B. sylvaticum in particular competes with conifers;however, several lines of evidence suggest that this grass will reduce survival and growth of conifer seedlings. First, a number of studies have established that the germination, growth and survival of conifers are negatively affected by competition with grasses (e.g. Powell et al., 1994;Lehmkuhl, 2002;Kruse et al., 2004). Second, at least one timber company (Starker Forests Inc.) has noticed that dense patches of false-brome provide safe cover for voles, which girdle conifer seedlings (G Fitzpatrick, The Nature Conservancy, Oregon, USA, personal communication, 2009). Third, none of the native grasses affected form a solid carpet in the forest, whereas B. sylvaticum does. These dense carpets will compete with seedlings in both logged and unlogged forests, and the build up of thatch may increase fire risk (Anzinger and Radosevich, 2008;False Brome Working Group, 2009). On the other hand, because B. sylvaticum remains green throughout the summer it may decrease fire risk (Anzinger and Radosevich, 2008;False Brome Working Group, 2009). These questions about fire need to be addressed with further research because this grass has the potential to cause ecosystem change if it alters fire behaviour.
The native grasses and herbs that live in the habitats being invaded are likely to diminish in cover and may face local extinction as a result of competition. A recent study showed that under shady high nutrient conditions, B. sylvaticum is a superior competitor to a native prairie grass (Festuca roemeri), a native forest grass (Elymus glaucus) as well as to another aggressive invasive Schedonorus arundinaceus (previously known as Festuca arundinacea) (BA Roy, University of Oregon, USA, personal observation, 2009). Two other grasses that occur sporadically in the forest (Melica subulata and Bromus carinatus) are also quite likely to be negatively affected. In its native range, B. sylvaticum is known for its ability to out compete other species due to its rapid relative growth rate (RGR) and ability to form persistent leaf litter (Grime et al., 1988;Haeggström and Skytén, 1996;Alonso et al., 2001).


Source: cabi.org
Description

Fusarium wilt of bananas is caused by F. oxysporum f.sp. cubense, a common soil inhabitant. Other formae speciales attack a wide variety of other crops, including cotton, flax, tomatoes, cabbages, peas, sweet potatoes, watermelons and oil palms.;The formae speciales of Fusarium oxysporum each produce three types of asexual spores. The macroconidia (22-36 x 4-5 µm, see Wardlaw, 1961 for measurements) are produced most frequently on branched conidiophores in sporodochia on the surface of infected plant parts or in artificial culture. Macroconidia may also be produced singly in the aerial mycelium, especially in culture. The macroconidia are thin-walled with a definite foot cell and a pointed apical cell. Oval or kidney-shaped microconidia (5-7 x 2.5-3 µm) occur on short microconidiophores in the aerial mycelium and are produced in false heads. Both macroconidia and microconidia may also be formed in the xylem vessel elements of infected host plants, but the microconidia are usually more common. The fungus may be spread by macroconidia, microconidia and mycelium within the plant as well as outside the plant. Illustrations of the conidia have been published (Nelson et al., 1983).;Chlamydospores (9 x 7 µm) are thick-walled asexual spores that are usually produced singly in macroconidia or are intercalary or terminal in the hyphae. The contents are highly refractive. Chlamydospores form in dead host-plant tissue in the final stages of wilt development and also in culture. These spores can survive for an extended time in plant debris in soil.;Mutation in culture is a major problem for those working with vascular wilt isolates of F. oxysporum. The sporodochial type often mutates to a 'mycelial' type or to a 'pionnotal' type. The former has abundant aerial mycelium, but few macroconidia, whereas the latter produces little or no aerial mycelium, but abundant macroconidia. These cultures may lose virulence and the ability to produce toxins. Mutants occur more frequently if the fungus is grown on a medium that is rich in carbohydrates.

Symptons

Banana;The various symptoms of Fusarium wilt on banana are described and well illustrated by Ploetz and Pegg (1999).;The first external symptoms of Fusarium wilt on bananas is a faint off-green to pale-yellow streak or patch at the base of the petiole of one of the two oldest leaves. The disease can then progress in different ways. The older leaves can yellow, beginning with patches at the leaf margin. Yellowing progresses from the older to the younger leaves until only the recently unfurled or partially unfurled centre leaf remains erect and green. This process may take from 1 to 3 weeks in cultivar 'Gros Michel'. Often the yellow leaves remain erect for 1-2 weeks or some may collapse at the petiole and hang down the pseudostem. In contrast to this 'yellow syndrome', leaves may remain completely green except for a petiole streak or patch but collapse as a result of buckling of the petiole. The leaves fall, the oldest first, until they hang about the plant like a skirt. Eventually, all leaves on infected plants fall down and dry up. The youngest are the last to fall and often stand unusually erect.;Splitting of the base of the pseudostem is another symptom as is necrosis of the emerging heart leaf. Other symptoms include irregular, pale margins on new leaves and the wrinkling and distortion of the lamina. Internodes may also shorten (Stover, 1962, 1972, Jones, 1994, Moore et al., 1995).;The characteristic internal symptom of Fusarium wilt is vascular discoloration. This varies from one or two strands in the oldest and outermost pseudostem leaf sheaths in the early stages of disease to heavy discoloration throughout the pseudostem and fruit stalk in the later disease stages. Discoloration varies from pale yellow in the early stages to dark red or almost black in later stages. The discoloration is most pronounced in the rhizome in the area of dense vascularization where the stele joins the cortex. When symptoms first appear, a small or large portion of the rhizome may be infected. Eventually, almost the entire differentiated vascular system is invaded. The infection may or may not pass into young budding suckers or mature 'daughter' suckers. Where it does, discoloration of vascular strands may be visible in the excised sucker. Usually, suckers less than 1.5 m tall and ca. 4 months old do not show external symptoms. Where wilt is epidemic and spreading rapidly, suckers are usually infected and seldom grow to produce fruit. Above- and below-ground parts of affected plants eventually rot and die.;Fusarium wilt was reported to occur on banana cultivars of the 'Mutika-Lujugira' (AAA genome) subgroup in East Africa above 1400 m. Internal symptoms were much less extensive than those described above and external symptoms more subtle, comprising thin pseudostems and small fingers. Nevertheless, symptomatic plants were recognized by smallholders and were rogued. These mild symptoms were initially believed to be indicative of an attack on a plant whose defences have been weakened as a result of cooler conditions or other predisposing factors at altitude (Ploetz et al., 1994). Given the importance of this banana group, also referred to locally as ÔEast African highland bananasÕ, to local trade and as a staple food, further investigation was merited. This revealed that the disorder also affected non-indigenous banana types, including Cavendish and Bluggoe (which were not affected by Fusarium wilt) and was related to abnormal soil nutrient levels and farm management practice. Discoloration similar to that caused by F. oxysporum f.sp. cubense was observed in vascular tissues of affected plants. Fusarium pallidoroseum (syn. Fusarium semitectum) was consistently isolated from such tissues but found to be non-pathogenic. F. oxysporum was not recovered (Kangire and Rutherford, 2001, Rutherford, 2006).

Hosts

F. oxysporum f.sp. cubense is one of around 100 formae speciales (special forms) of F. oxysporum which cause vascular wilts of flowering plants (Gerlach and Nirenberg, 1982). Hosts of the various formae speciales are usually restricted to a limited and related set of taxa. As currently defined, F. oxysporum f.sp. cubense affects the following species in the order Zingiberales: in the family Musaceae, Musa acuminata, M. balbisiana, M. schizocarpa and M. textilis, and in the family Heliconeaceae, Heliconia caribaea, H. chartacea, H. crassa, H. collinsiana, H. latispatha, H. mariae, H. rostrata and H. vellerigera (Stover, 1962, Waite, 1963). Additional hosts include hybrids between M. acuminata and M. balbisiana, and M. acuminata and M. schizocarpa.;F. oxysporum f.sp. cubense may survive as a parasite of non-host weed species. Three species of grass (Paspalum fasciculatum, Panicum purpurascens [ Brachiaria mutica ] and Ixophorus unisetus) and Commelina diffusa have been implicated (Waite and Dunlap, 1953).


Source: cabi.org
Description

Adult Papuana huebneri are black, shiny and 15-20 mm long. The size and number of head horns in taro beetles varies between species and sexes;P. huebneri has only one small horn, which is larger in the male than the female (Macfarlane, 1987a).

Recognition

Taro beetles can be detected by: (1) digging up wilting taro plants and examining them for signs of damage;(2) using light traps, particularly on moonless and rainy nights;and (3) sampling wild plant species (e.g. banana, sugarcane and grasses such as Paspalum spp. and Brachiaria mutica) at breeding sites, especially along river banks, on rotting logs and in compost heaps (Carmichael et al., 2008;Tsatsia and Jackson, 2014;TaroPest, 2015).

Symptons

Adult taro beetles burrow into the soft trunks, plant bases and corms of a range of plants, including taro, making large holes or cavities up to 2 cm in diameter (McGlashan, 2006). The feeding tunnels and associated frass may be visible in infested corms (Biosecurity Australia, 2011). The amount of damage to the crop depends on the age of the plants when attacked and the density of infestation. Feeding activity can cause wilting and even the death of affected plants, particularly in young plants if the beetles bore into the growing points. Older plants infested by beetles grow slowly and a few or all of the leaves wilt (TaroPest, 2015). In severely damaged plants tunnels may run together to form large cavities, making the damaged corms more susceptible to fungal infections (Macfarlane, 1987a;Onwueme, 1999). Similar symptoms of damage are caused to other root crops, e.g. sweet potato, yams and potato (McGlashan, 2006). Taro beetles can ring-bark young tea, cocoa and coffee plants in the field and bore into seedlings of oil palm and cocoa (Aloalii et al., 1993).

Impact

Papuana huebneri is one of at least 19 species of known taro beetles native to the Indo-Pacific region;it is native to Papua New Guinea, the Molucca Islands in Indonesia, the Solomon Islands and Vanuatu, and has been introduced to Kiribati. Taro (Colocasia esculenta) is an important crop in these countries;high infestations of P. huebneri can completely destroy taro corms, and low infestations can reduce their marketability. The beetle also attacks swamp taro or babai (Cyrtosperma chamissonis [ Cyrtosperma merkusii ]), which is grown for consumption on ceremonial occasions. Infestations of taro beetles, including P. huebneri, have led to the abandonment of taro and swamp taro pits in the Solomon Islands and Kiribati, resulting in the loss of genetic diversity of these crops and undermining cultural traditions. P. huebneri also attacks a variety of other plants, although usually less seriously. Management today relies on an integrated pest management strategy, combining cultural control measures with the use of insecticides and the fungal pathogen Metarhizium anisopliae.

Hosts

Papuana huebneri is a pest of taro (Colocasia esculenta;known as ‘dalo’ in Fijian;McGlashan, 2006) (Masamdu, 2001;International Business Publications, 2010), which is grown primarily as a subsistence crop in many Pacific Island countries, including Kiribati, Papua New Guinea, the Solomon Islands and Vanuatu, where P. huebneri is found (Aloalii et al., 1993). Taro also has value in gift-giving and ceremonial activities (Braidotti, 2006;Lal, 2008). The beetle also attacks swamp taro or babai (Cyrtosperma merkusii or Cyrtosperma chamissonis), which is grown for consumption on ceremonial occasions (Food and Agriculture Organization, 1974;Dharmaraju, 1982;International Business Publications, 2010).
Other plants attacked by Papuana huebneri include tannia (Xanthosoma sagittifolium), bananas (Musa spp.), Canna lily (Canna indica), pandanus (Pandanus odoratissimus [ Pandanus utilis or P. odorifer ]), the bark of tea (Camellia sinensis), coffee (Coffea spp.) and cocoa (Theobroma cacao), the fern Angiopteris evecta (Masamdu, 2001), and occasionally the Chinese cabbage Brassica chinensis [ Brassica rapa ] (International Business Publications, 2010).
Species of Papuana behave similarly to each other and feed on the same host plants (TaroPest, 2015). For taro beetles in general, primary host plants other than taro include giant taro (Alocasia macrorrhizzos), Amorphophallus spp., the fern Angiopteris evecta, banana (Musa spp.) and tannia (Xanthosoma sagittifolium). Secondary hosts include pineapple (Ananas comosus), groundnut (Arachis hypogaea), betel nut (Areca catechu), cabbage (Brassica oleracea), canna lily (Canna indica), coconut (Cocos nucifera), Commelina spp., Crinum spp., yam (Dioscorea spp.), oil palm (Elaeis guineensis), sweet potato (Ipomoea batatas), Marattia spp., pandanus (Pandanus odoratissimus [ Pandanus utilis or P. odorifer ]), Saccharum spp. including sugarcane (Saccharum officinarum) and Saccharum edule [ Saccharum spontaneum var. edulis ], and potato (Solanum tuberosum);they occasionally ring bark young tea (Camellia sinensis), coffee (Coffea spp.) and cocoa (Theobroma cacao) plants (Macfarlane, 1987b;Aloalii et al., 1993;Masamdu and Simbiken, 2001;Masamdu, 2001;Tsatsia and Jackson, 2014;TaroPest, 2015).


Source: cabi.org
Description

D. suzukii adults are 2-3 mm long with red eyes, a pale brown or yellowish brown thorax and black transverse stripes on the abdomen. The antennae are short and stubby with branched arista. Sexual dimorphism is evident: males display a dark spot on the leading top edge of each wing and females are larger than males and possess a large serrated ovipositor.

Recognition


Detailed morphological description of each stage is given by Kanzawa (1935). A more recently updated description, including references for additional morphological details, is given by Hauser (2011), and another by Vlach (2010), who published a dichotomous key for easy identification. An easy-to-use description of the combination of diagnostic characters that could be used for tentative identification of D. suzukii within its subgroup is given by both Hauser (2011) and Cini et al. (2012). Fruit infestation symptoms are described by Walton et al. (2010).
The dark spots on the male wings together with two sets of black tarsal combs make the identification of the males relatively easy, although the males of some other species do also have wing spots. The wing spots of D. subpulchrella are particularly similar in shape and position to those of D. suzukii. Males without dark wing spots can occur, as it takes two full days before the spots become obvious, although they start to appear within 10 hours of emergence at high temperatures.
The situation is complex for the eggs, larvae and pupae, as no reliable morphological diagnostic features have been identified (Okada, 1968). The eggs of D. suzukii have two respiratory appendages but this character is not species-specific. Instar stages can be estimated by the size of larvae and the colour of the mouthparts, but it is most accurately judged by pre-respiratory ducts (Kanzawa, 1935;Walsh et al., 2011).
Larvae are often undetected inside the fruit. The infested fruits can be detected only by visual inspection under optical magnification (15-20 x magnification). Detection of larvae inside the fruits can also be performed by immersion of fruit samples in sugar or salt solution. Sugar solution can be prepared using approximately 1 part sugar to 6 parts water in order to reach at least 15°Brix. Gently crush the fruits and wait for 10 minutes until the larvae in the sample float to the surface. The same procedure can also be followed using a salt solution, adding 1 part salt to 16 parts water (BCMA, 2013).
Traps baited with different baits have been proposed for detecting adults in the field. Traps can be installed around a site where fruits for shipment are stored, and for early detection in potentially newly-invaded areas, such as near fruit markets, warehouses of food retailers and sites where rotten fruits are disposed. For more information on traps and baits, see the Monitoring and Surveillance section in Prevention and Control.

Symptons

D. suzukii larvae cause damage by feeding on the pulp inside fruit and berries. The infested fruit begins to collapse around the feeding site causing a depression or visible blemish on the fruit. The oviposition scar exposes the fruit to secondary attack by pathogens and other insects, which may cause rotting (Hauser et al., 2009;Walton et al., 2010).

Impact


The fruit fly D. suzukii is a fruit crop pest and is a serious economic threat to soft summer fruit. A polyphagous pest, it infests a wide range of fruit crops, included grape, as well as an increasing number of wild fruits. D. suzukii is an economically damaging pest because the females are able to infest thin-skinned fruits before harvest and the larvae destroy the fruit pulp by feeding. The species is endemic in Asia. It was first recorded as invasive in Hawaii in 1980 and then simultaneously in California and in Europe in 2008. Since 2008 it has spread rapidly throughout the temperate regions of North America and Europe, due to global trade and the initial lack of regulation over the spread of any Drosophila. This species has a high reproductive rate and short generation time;D. suzukii can theoretically have up to 13 generations per year, which may contribute towards rapid spread, given available suitable hosts. D. suzukii is listed on the EPPO alert list.

Hosts

D. suzukii is predisposed towards infesting and developing in undamaged, ripening fruit. Fruits become susceptible to D. suzukii as they start to change colour, which coincides with softening skins and higher sugar levels (Burrack et al., 2013). There are differences in fruit susceptibility within species and among varieties within the same fruit species (Lee et al., 2011). Fruit penetration force is one potential measure of host susceptibility, but host attractiveness will likely depend upon additional factors, such as soluble sugar content (Burrack et al., 2013). If there is no suitable fruit available, then D. suzukii will attack damaged or deteriorating fruit (Kanzawa, 1935;Lee et al., 2011). Non-commercially marketed fallen fruit or damaged fruit of the following plant hosts may also be attacked: Prunus persica, Malus pumila var. domestica, Prunus triflora, Prunus armeniaca, Pyrus pyrifolia, Pyrus sinensis, Eriobotrya japonica, Lycopersicum esculentum (Kanzawa, 1939) and Rubus microphyllus (Mitsui et al., 2010), as well as over-ripped figs still on the tree (Ficus carica) (Yu et al., 2013).
D. suzukii has been reared from rotting strawberry guava fruits (Psidium cattleianum) collected from trees and on the ground (Kido et al., 1996). It has been observed feeding upon injured or culled fruit including apple and oranges (Walsh et al., 2001).
A recently extensive study on seasonal life cycles and food resources of D. suzukii from low to high altitudes in central Japan (Mitsui et al., 2010) confirmed that D. suzukii emerges almost only from fruits. Some D. suzukii individuals emerged from the fruits of Rubus crataegifolius, Alangium platanifolium, Cornus kousa, Torreya nucifera and Viburnum dilatatum. Grassi et al. (2011) reared D. suzukii also on Prunus laurocerasus and Mann and Stelinski (2011) reported Ribes spp. as host plant of D. suzukii, but this latest observation has not been confirmed in Europe. D. suzukii adults also emerged from the flowers of Styrax japonicus (Mitsui et al., 2010), and in early spring in southern Japan it was also observed to breed on the flowers of Camellia japonica (Nishiharu, 1980).
This field of work is not well described, and so the list of Host Plants and Other Plants Affected contains probable as well as reported hosts.

Biological Control
Early experiments tested the efficacy of Phaenopria spp. (Hymenoptera: Diapriidae) under laboratory conditions, but results were unsatisfactory (Kanzawa, 1939).<br>Studies to determine the current presence of indigenous parasitoid biological control agents and their efficacy in controlling D. suzukii were undertaken both in North America and in Europe by different research groups (Brown et al., 2011;Chabert et al., 2012;Rossi Stacconi et al., 2013). Under laboratory conditions several naturally occurring parasitoids of drosophilids in France were able to successfully parasitize D.suzukii. These included two larval parasitoids, Leptopilina heterotoma and Leptopilina boulardi, and two pupal parasitoids, Pachycrepoideus vindemiae (Hymenoptera: Pteromalidae) and Trichopria drosophilae (Hymenoptera: Diapriidae). Both Leptopilina parasitoids displayed high parasitism rates on D. suzukii, but because of the strong immune response of the host larvae, they did not give rise to an adult wasp (Chabert et al., 2012).<br>D. suzukii produces up to five times more hemocytes than D. melanogaster, making it significantly more resistant to wasp parasitism (Kacsoh and Schlenke, 2012) and making it less likely for indigenous specialized parasitoids to shift host onto it. While parasitization by L. heterotoma induced a decrease in the number of circulating haemocytes in D. melanogaster, it led to a large increase in the total haemocyte counts of D. suzukii (Poyet et al., 2013).<br>The observed difference between the immune response towards L. heterotoma in D. suzukii and D. melanogaster could suggest that European populations of L. heterotoma are not adapted to this new exotic host (Poyet et al., 2013);however, this hypothesis disagrees with the recent observations of a European-wide strain of L. heterotoma that is able to develop and emerge from D. suzukii. (Rossi Stacconi et al., 2013). It is probable that the European-wide strain of L. heterotoma has more effective venom, or that the strain of L. heterotoma used in the original study had lost its ability to develop on D. suzukii because of continued laboratory rearing on D. melanogaster.<br>Pupal parasitoids seem less susceptible to the high hemocyte levels of D. suzukii and they appear to have the highest potential for use in biocontrol of D. suzukii (Kacsoh and Schlenke, 2012). This was confirmed by the successful parasitism rate obtained with a pupal parasitoid by Chabert et al. (2012).<br>The pupal ectoparassitoid P. vindemiae has also been found in association with D. suzukii in orchards and vineyards, both in USA and in Europe (Brown et al., 2011;Rossi Stacconi et al. 2013).<br>Predators of D. suzukii include several species of the bug genus Orius, a generalist predator, which were observed feeding on D. suzukii larvae in backyard raspberries in the autumn of 2009 (Walsh et al., 2011). Preliminary laboratory studies with O. insidiosus (Walsh et al., 2011), O. laevigatus and O. maiusculus (V. Malagnini, personal comm.) indicated that they can feed on D. suzukii larvae infesting blueberries, but their effective control of the pest population have not been proved yet.<br>The activity of microorganisms, as well as the intimate association of the pest species with endosymbionts, has not yet been exploited for biocontrol purpose.<br>Recently, DNA viruses have been isolated in Drosophila species (Unkless, 2011) and were found to be related to other viruses used for pest control.<br>Strains of endosymbiotic bacterium Wolbachia associated with D. suzukii populations have been collected in both the USA and Italy (Siozios et al., 2013;Tochen et al., 2014). These findings suggest the possibility of control of D. suzukii based on pathogens.

Source: cabi.org
Description

B. cockerelli adults are small, measuring about 2.5-2.75 mm long. The adults generally resemble tiny cicadas, largely because they hold their wings angled and roof-like over their body. B. cockerelli adults possess two pairs of clear wings;the front wings bear conspicuous veins and are considerably larger than the hind wings. The antennae are moderately long, extending almost half the length of the body. The overall body colour ranges from pale green at emergence to dark green or brown within 2-3 days, and eventually becomes grey or black thereafter. Prominent white or yellow lines are found on the head and thorax, and dorsal whitish bands are located on the first and terminal abdominal segments. These white markings are spot characteristics of the psyllid, particularly the broad, transverse white band on the first abdominal segment and the inverted ‘V’-shaped white mark on the last abdominal segment (Pletsch, 1947;Wallis, 1955), along with the raised white line around the circumference of the head. Adults are active in contrast to the largely sedentary nymphal stages. These insects are good fliers and readily jump when disturbed.

Symptons

B. cockerelli has historically been associated with ‘psyllid yellows’ disease of potato and tomato (Richards and Blood, 1933). Psyllid yellows disease is thought to be associated with feeding by psyllid nymphs (List, 1925) and may be caused by a toxin associated with the insect (Carter, 1939), although the actual etiology of the disease is yet to be determined (Sengoda et al., 2010). More recently, this psyllid has been found to be associated with the bacterium ‘ Candidatus Liberibacter’ (Hansen et al., 2008;Liefting et al., 2009;Crosslin et al., 2010;Munyaneza, 2010;Munyaneza, 2012;Munyaneza and Henne, 2012) (see ISC datasheet on ‘ Candidatus Liberibacter solanacearum’ for details).
The characteristic above-ground plant symptoms of infestation by B. cockerelli in potatoes and tomatoes include retarded growth, erectness of new foliage, chlorosis and purpling of new foliage with basal cupping of leaves, upward rolling of leaves throughout the plant, shortened and thickened terminal internodes resulting in rosetting, enlarged nodes, axillary branches or aerial potato tubers, disruption of fruit set and production of numerous, small, and poor quality fruits (List, 1939;Pletsch, 1947;Daniels, 1954;Wallis, 1955;Munyaneza, 2012;Munyaneza and Henne, 2012).
The below-ground symptoms on potato include the setting of an excessive number of tiny misshapen potato tubers, production of chain tubers and early breaking of dormancy of tubers (List, 1939;Pletsch, 1947;Wallis, 1955). Additional potato tuber symptoms include collapsed stolons, browning of vascular tissue concomitant with necrotic flecking of internal tissues and streaking of the medullary ray tissues, all of which can affect the entire tuber. Upon frying, these symptoms become more pronounced and chips or fries processed from affected tubers show very dark blotches, stripes, or streaks, rendering them commercially unacceptable (Munyaneza et al., 2007a,b;2008;Secor et al., 2009;Crosslin et al., 2010;Miles et al., 2010;Munyaneza, 2012;Munyaneza and Henne, 2012);see the ISC datasheet on ' Candidatus Liberibacter solanacearum' for details.

Impact

B. cockerelli is one of the most destructive potato pests in the western hemisphere. It was recognized in the early 1900s that B. cockerelli had the potential to be an invasive and harmful insect, particularly in western United States and Mexico (Šulc, 1909;Crawford, 1914;Compere, 1915;1916;Essig, 1917). By the 1920s and 1930s, B. cockerelli had become a serious and destructive pest of potatoes in most of the southwestern United States, giving rise to the description of a new disease that became known as ‘psyllid yellows’ (Richards, 1928;1931;1933;Binkley, 1929;Richards and Blood, 1933;List and Daniels, 1934;Pletsch, 1947;Wallis, 1955).

Hosts

B. cockerelli is found primarily on plants within the family Solanaceae. The psyllid attacks, reproduces and develops on a variety of cultivated and weedy plant species (Essig, 1917;Knowlton and Thomas, 1934;Pletsch, 1947;Jensen, 1954;Wallis, 1955), including crop plants such as potato (Solanum tuberosum), tomato (Solanum lycopersicon), pepper (Capsicum annuum), eggplant (Solanum melongena) and tobacco (Nicotiana tabacum) as well as non-crop species such as nightshade (Solanum spp.), groundcherry (Physalis spp.) and matrimony vine (Lycium spp.).
Adults have been collected from plants in numerous families, including Pinaceae, Salicaceae, Polygonaceae, Chenopodiaceae, Brassicaceae, Asteraceae, Fabaceae, Malvaceae, Amaranthaceae, Lamiaceae, Poaceae, Menthaceae and Convolvulaceae, but this is not the complete host range of this psyllid (Pletch, 1947;Wallis, 1955;Cranshaw, 1993). Beside solanaceous species, B. cockerelli has been shown to reproduce and develop on some Convolvulaceae species, including field bindweed (Convolvulus arvensis) and sweet potato (Ipomoea batatas) (Knowlton and Thomas, 1934;List, 1939;Wallis, 1955;Puketapu and Roskruge, 2011;Munyaneza, unpublished data).


Source: cabi.org
Description


In life, adult females are oval, up to 5 mm long, greyish-yellow, with two longitudinal, submedian, interrupted dark stripes on the dorsum showing through the waxy secretion -- hence the common name 'striped mealybug'. The dorsum also bears numerous straight, glassy threads of wax up to 4.0-4.5 mm long. Several members of the genus Ferrisia have this appearance in life, so authoritative identification requires expert study of stained, slide-mounted adult females using the key in Kaydan and Gullan (2012), or nucleotide sequence data.
Slide-mounted adult female Ferrisia species are easy to recognise by the presence of only one pair of cerarii, situated on the anal lobes, and the presence of enlarged tubular ducts, each with the orifice surrounded by a flat, circular, sclerotized area associated with one or more short setae. Kaydan and Gullan (2012) provided a thorough revision of the genus Ferrisia and a morphological key to world species, including detailed morphological description, illustration and discussion of F. virgata. F. virgata is very difficult to separate from some of the other species, particularly F. dasylirii. It has both anterior and posterior pairs of ostioles;ventral oral-collar tubular ducts of at least 2 sizes;smaller ducts present singly or in segmental clusters on body margin, only on last 2–3 abdominal segments;minute discoidal pores in sclerotised area of enlarged dorsal tubular ducts and larger ventral oral-collar tubular ducts rarely if ever touching rim of duct opening (or only very rarely on ventral ducts);discoidal pores associated with sclerotised area around orifices of dorsal enlarged tubular ducts on anterior abdomen normally not touching outer margin of sclerotised area and very rarely projecting from that margin;dorsal enlarged tubular ducts numbering 69-101;abdominal segment VI with 11-28 multilocular disc pores, usually with more than 15 in a double row;each anal lobe cerarius with 3 (occasionally 2) enlarged conical setae;and hind coxa with translucent pores (Kaydan and Gullan, 2012).

Recognition


Heavy infestations are conspicuous because of the white waxy secretions, white masses of male tests (waxy filamentous cocoons) and sooty moulds growing on the excreted honeydew. Colonies often occur at the growing points, around the stem nodes, on the undersides of leaves and on the fruit.

Symptons


Infestations of F. virgata remain clustered around the terminal shoots, leaves and fruit, sucking plant sap which results in yellowing, withering and drying of plants and premature shedding of leaves and fruit. The mealybugs do not feed on phloem very often, so unlike many mealybug species they do not produce huge quantities of sugary honeydew. What honeydew is produced can foul foliage and fruit and serve as a medium for the growth of black sooty moulds. Sooty moulds and wax deposits can block light and air from the plant, sometimes reducing photosynthesis and hence plant vigour and crop yield.

Impact

Ferrisia virgata is a highly polyphagous mealybug. It reproduces quite rapidly in tropical conditions, but it tolerates subtropical and to some extent temperate conditions too. It has been reported on host-plants belonging to over 203 genera in 77 families, and can damage many crops, particularly tropical fruit, nut and spice crops and field crops like soybean and tomato. It is known to transmit plant badnavirus diseases of cocoa and black pepper. It is of Neotropical origin and spread around the world in only about 10 years after being first described from Jamaica. Its polyphagy has facilitated its spread by human transport of infested plants, and it is now established in all the subtropical and tropical zoogeographic regions. Its small size and cryptic habits make it difficult to detect and identify at plant quarantine inspection. The increase in international trade in fresh plant material in recent years is likely to facilitate its continued spread.

Hosts

F. virgata is one of the most highly polyphagous mealybugs known, attacking plant species belonging to some 203 genera in 77 families (García et al., 2016). Many of the host species belong to the Fabaceae and Euphorbiaceae. Among the hosts of economic importance are avocado, banana, betel vine, black pepper, cassava, cashew, cauliflower, citrus, cocoa, coffee, cotton, custard apple, aunergine, grapevine, guava, jute, lantana, Leucaena, litchi, mango, oil palm, pigeon pea, pineapple, soyabean and tomato. Acalypha species are apparently a favoured host-plant in many places (Kaydan and Gullan, 2012).


Source: cabi.org
Description

Larva
For identification of the third-instar larva, see White and Elson-Harris (1994).
Adult
C. capitata belongs to a group of eight or nine species placed in the subgenus Ceratitis s.s. (De Meyer, 2000). The adults are readily recognisable by external morphology, particularly thoracic and wing patterns (White and Elson-Harris, 1994). The males have a characteristically shaped pair of lower orbital setae, the apex black and diamond-shaped. For a complete description see De Meyer (2000), who also provides a key for the separation of similar species.

Recognition

C. capitata can be monitored by traps baited with male lures. As in other tested species belonging to the subgenus Ceratitis, males are attracted to trimedlure and terpinyl acetate, but not methyl eugenol. Ceralure is a new potent and persistent attractant for C. capitata (Avery et al., 1994). The responses to baits of 16 Ceratitis species were tabulated by Hancock (1987). Trimedlure (t-butyl-4(or 5)-chloro-2-methyl cyclohexane carboxylate) is the most widely used lure for C. capitata. The history of trimedlure development and the problems of isolating the best of the eight possible isomers were discussed by Cunningham (1989a). The lure is usually placed on a cottonwool wick suspended in the middle of a plastic trap that has small openings at both ends. Suitable traps were described by White and Elson-Harris (1994). Lure can either be mixed with an insecticide or a piece of paper dipped in dichlorvos can be placed in the trap. Traps are usually placed in fruit trees at a height of about 2 m above ground and should be emptied regularly as it is possible to catch hundreds of flies in a single trap left for just a few days, although the lure may remain effective for a few weeks. A detailed study of trap position effects was carried out by Israely et al. (1997). A review of the biological aspects of male lures was presented by Cunningham (1989a) and the use of lures was described more fully by Drew (1982). A trapping system used to monitor for possible introductions of C. capitata into New Zealand has been described by Somerfield (1989). The possibility of the development of pheromone-based trapping systems was discussed by Landolt and Heath (1996). Trapping efficiency may also be enhanced by the use of fluorescent colours, particularly light green (Epsky et al., 1996).

Impact

C. capitata is a highly invasive species. It has a high dispersive ability, a very large host range and a tolerance of both natural and cultivated habitats over a comparatively wide temperature range. It has a high economic impact, affecting production, control costs and market access. It has successfully established in many parts of the world, often as a result of multiple introductions (Malacrida et al., 2007). Frequent incursions into North America require expensive eradication treatments and many countries maintain extensive monitoring networks.

Hosts

C. capitata is a highly polyphagous species and its pattern of host relationships from region to region appears to relate largely to what fruits are available;examples were given by White and Elson-Harris (1994). Coffea spp. are especially heavily attacked, although the attack on coffee does not impact on this crop as only the fleshy part of the fruit, which is discarded, is utilised by the larvae. However, the quality may be affected and in many areas coffee crops appear to act as an important reservoir from which other crops may be attacked. In some areas wild hosts are of importance, for example, box thorn, Lycium europaeum, is an important overwintering host in North Africa (Cayol, 1996). Several wild hosts in Zimbabwe were recorded by Hancock (1987) and Copeland et al. (2002) recorded 51 wild host species in Kenya. Lists of wild and cultivated hosts were provided by Liquido et al. (1991), Hancock et al. (2000) and De Meyer et al. (2002). Reports in the literature of Hylocereus undatus as a host of C. capitata are not supported by field evidence (Zlotina, 2015).
In addition to the hosts listed, C. capitata has also been found on Artabotrys monteiroae, Berberis holstii, Bourreria petiolaris, Carissa longiflora, Carissa tetramera, Chrysophyllum carpussum, Coccinia microphylla, Corallocarpus ellipticus, Diospyros pubescens, Drypetes gerrardii, Elaeodendron schweinfurthianum, Grewia trichocarpa, Harrisonoia abyssinica, Lamprothamnus zanguebaricus, Ludia mauritiana, Lycium campanulatum, Manilkara sulcata, Mimusops kirkii, Minusops kummel, Mimusops zeheri, Peponium mackenii, Pentarhopalopilia umbellulata, Polysphaeria parvifolia, Richardella campechiana, Salacia elegans, Santalum freyinetianum, Vepris nobilis, V. simplicifolia and V. trichocarpa.


Source: cabi.org
Description

Eggs

Symptons

D. citri stunts and twists young shoots, so that the growing tips present a rosetted appearance. Leaves are badly curled, and may be covered with honeydew and sooty mould;leaves drop prematurely.

Hosts

D. citri is confined to the Rutaceae, occurring on wild hosts as well as on Citrus, especially lemons (C. limon), rough lemon (C. jambhuri), sour orange (C. aurantium), grapefruit (C. paradisi) and limes (C. aurantiifolia). Murraya paniculata, a rutaceous plant often used for hedges, is a preferred host;M. koenigii is a host in India and Sri Lanka.
Sétamou et al. (2016) observed that some native North American rutaceous plants can serve as host plants for D. citri, thus affecting the population dynamics of the pest and the epidemiology of Huanglongbing


Source: cabi.org
Description


Eggs - elliptical or ovoid in shape, milky-white and shiny when first laid, 0.5-0.8 mm long, 0.25-0.35 mm wide (Bergamin, 1943;Hernandez-Paz and Sanchez de Leon, 1978;Johanneson, 1984).

Recognition

H. hampei can be detected in the trees and coffee beans.
Tree - inspect the berries and look for a small cylindrical perforation. Look at the lower branches and fallen berries as these may be more likely to be infested. There are numerous sampling methods, many based on counting all berries on 30 or more branches over a hectare and evaluating percentage attack. As yet there is no easy or universal way to relate level of crop attack to future loss at harvest. A figure of 5% infested berries is often used as an economic threshold for field control activities, but more study on this is needed.
Coffee beans - as the perforation on berries may be difficult to see, rub suspect beans between the hands to remove the parchment and look for the perforation. Often a small indentation will be present where the borer started to attack but failed to establish itself.
A trap based on ethanol and methanol has been developed but it also catches many other scolytids. It is useful to monitor emergence flight activity, most notably when rains follow a dry period. French research has renewed interest in trapping as a form of control, initial results have been are encouraging though more research needs to be done to confirm the economic viability of this method (Dufour et al., 1999). Fernandes et al. (2014) found that mass trapping could reduce attacks, but not below an economic threshold.

Symptons


Attack by H. hampei begins at the apex of the coffee berry from about eight weeks after flowering. A small perforation about 1 mm diameter is often clearly visible though this may become partly obscured by subsequent growth of the berry or by fungi that attack the borer. During active boring by the adult female, she pushes out the debris, which forms a deposit over the hole. This deposit may be brown, grey or green in colour.
Infestation is confirmed by cutting open the berry. If the endosperm is still watery, the female will be found in the mesoderm between the two seeds, waiting for the internal tissues to become more solid. If the endosperm is more developed, the borer will normally be found there amongst the excavations and irregular galleries that it has made. The borer sometimes causes the unripe endosperm to rot, most commonly by species Erwinia, causing it to turn black (Sponagel, 1994) and the borer to abandon the berry.

Impact

H. hampei, otherwise known as the coffee berry borer, is the most serious pest of coffee in many of the major coffee-producing countries in the world. The scolytid beetle feeds on the cotyledons and has been known to attack 100% of berries in a heavy infestation. Crop losses can be very severe and coffee quality from damaged berries is poor. H. hampei has been transported around the world as a contaminant of coffee seed and very few coffee-producing countries are free from the borer. Its presence in Hawaii was confirmed in 2010 and Papua New Guinea and Nepal remain free of the pest: in Papua New Guinea an incursion prevention programme was mounted in 2007 (ACIAR, 2013) to reduce chances of invasion from Papua Province (Indonesia). There is no simple and cheap method of control of H. hamepi.

Hosts

H. hampei is sometimes reported attacking and breeding in plants other than coffee, however there are few convincing published studies of this with supporting expert taxonomic identification. However, a Colombian study (L Ruiz, Cenicafé, Centro Nacional de Investigaciones de Café, Colombia, personal communication, 1994) reports rearing the borer through to adulthood on seeds of Melicocca bijuga and a Guatemalan study (O Campos, Anacafé, Asociacion Nacional del Café, Guatemala, personal communication, 1984) reports the same for Cajanus cajan. Vega et al. (2012) reviewing older little-known literature including that of Schedl (1960), make the case that the African host range may be broader than previously suspected. As there is much current interest in mass production of the borer, further studies of alternative food sources would be of interest. Nevertheless, all field studies of the borer suggest that coffee is the only primary host and that population fluctuations are hence due almost entirely to its interaction with coffee and not to the presence of alternative hosts.

Host plant resistance

Chevalier (cited in Le Pelley, 1968) found Coffea liberica almost immune to H. hampei followed by C. excelsa, C. dewerei, C. canephora and C. arabica in increasing order of attractiveness to the borer. Villagran (1991) found that. H. hampei had difficulty in penetrating the hard exterior of C. liberica berries. However, Roepke (in Le Pelley, 1968) states that C. liberica is preferentially attacked. Extensive studies by Kock (1973) reported C. canephora variety Kouilou (or Quoillou) is attacked less than the Robusta variety.
Villagran (1991) found C. kapakata supporting very significantly fewer immature stages of the borer than other varieties and some tendency for C. arabica variety Mundo Novo also to support fewer progeny. Olfactometry tests by Duarte (1992) showed C. kapakata to be significantly less attractive. C. kapakata appears to be one of the most resistant coffee species currently known but this is not a commercial variety and neither the berries nor the plant resemble a coffee plant to the casual observer.
Romero and Cortina-Guererro (2004) in laboratory studies in Colombia found no difference in levels of antixenosis (deterrence to attack coffee in field tests) of various coffee varieties (including C. arabica Caturra, various Ethiopian accessions as well as C. liberica). However Romero and Cortina-Guererro (2007) did find differences in antibiosis (expressed as fecundity) with Ethiopian accession CC532 and C. liberica both yielding significantly fewer borer progeny.
Gongora et al. (2012) confirmed the inhibitory effects of C. liberica through a functional genomics study using ESTs libraries, cDNA microarrays and an oligoarray containing 43,800 coffee sequences. The results allowed for a comparison of C. liberica vs. C. arabica berry responses to H. hampei infestation after 48 h. Out of a set of 2500 plant sequences that exhibited differential expression under H. hampei attack, twice the number were induced in C. liberica, than in C. arabica. One of the identified biochemical pathways was the one that leads to the production of isoprene. The authors studied the effect of isoprene on H. hampei by monitoring the development of the insect from egg to adult, using coffee-artificial diets amended with increasing concentrations of isoprene. Concentrations of isoprene above 25 ppm caused mortality and developmental delay in all insect stages from larva to adult, as well as the inhibition of larvae moulting.
Hence it seems certain that varying amounts of resistance or antibiosis to the borer exists within species of Coffea. Such resistance to attack or even moderate antibiosis is worthy of further study because an increase in development time and/or decrease in fecundity could have a pronounced effect on infestation levels. Conventional breeding to introduce such inhibition from outside the Arabica genome might be difficult however, hence genetic engineering may be increasingly considered in the future.
A team of CIRAD scientists were the first to succeed in producing a transgenic coffee plant with Bt resistance to leafminers but there is no information about its effect on H. hampei (Leroy et al., 2000). Scientists from Brazil and Colombia (Barbosa et al., 2010) transformed C. arabica by introducing an enzyme inhibitor from the common bean (Phaseolus vulgaris). Beans have evolved an amylase enzyme inhibitor (or ‘starch blocker’) to make them less palatable to attacking insects. They demonstrated that crude seed extracts from genetically transformed C. arabica plants expressing the α-amylase inhibitor-1 gene (α-AI1) under the control of the common bean P. vulgaris seed-specific promoter PHA-L, inhibited 88 % of H. hampei α-amylases during in vitro assays. Since then, offspring from these GM coffee plants have been cultivated under greenhouse conditions to study the heredity, stability and expression of the α-AI1 gene. Subsequently Albuquerque et al. (2015) carried out in vivo assays of H. hampei development in berries of the transformed plants. A 26-day assay showed that the lifecycle of H. hampei was still completed, though significantly fewer offspring developed than on non-transformed control beans. Other tests showed that gene expression occurred only in the endosperm tissue. Commercial interest in developing transgenic coffee resistant to pests and diseases is still low however and might meet considerable consumer resistance.

Monitoring

Theoretically it would be possible to develop a forecasting model to predict upsurges of H. hampei, because under some conditions, especially after a long dry spell with high temperatures, large populations develop on fallen berries which then emerge after early rains. This however would require regular field monitoring and dissections of sampled berries and the costs of mounting such an exercise are probably too high. However, even occasional and non-intensive monitoring of borer during the post-harvest dry season, could give field technicians a feel for the build-up of populations that could be translated into warnings to farmers in exceptional circumstances. Recent El Niño events which cause prolonged hot and dry conditions, almost invariably give rise to an upsurge in infestations.
Traps with a 1:1 ethanol + methanol lure can be used to trap flying borer. Numbers caught relate quite closely to nearby total populations (Mathieu et al., 1999) so could be used to monitor borer populations. However, the traps placed outside an infested plot catch very few insects, so the power of the trap is low. This means that its use to detect borer flying into a quarantined zone is questionable. For that purpose simply checking coffee trees for infestations is probably quicker, more sensitive and cheaper. This is probably also true for routine monitoring of borer populations. Traps are now used sometimes as part of an IPM control strategy, i.e. for control rather than monitoring (Dufour and Frérot, 2008). Spectacular catches have been achieved in El Salvador (Dufour et al., 2004) and were related to measured declines in infestation. However results can be very variable. Fernandes et al. (2014) deployed 900 traps in four coffee farms and achieved a 57% reduction infestation, but levels were still above an economic loss threshold. It seems likely that traps can be effective in specific conditions, when placed after early rains when borers are emerging and when there are few berries to compete for the traps’ attractiveness. However the proportion of borers trapped to total infestation levels is always low 5%) so it is questionable whether traps are cost effective, especially since they need regular servicing to replenish the lure, clear debris etc., something that most farmers are not good at. Hence the traps need to be evaluated for specific coffee-growing conditions and results weighed against costs of the traps, their regular servicing and farmers’ willingness to service them regularly.

Biological Control
The two bethylid parasitoids, Cephalonomia stephanoderis and Prorops nasuta have been introduced from Africa to India and many Latin-American countries in the 1980s and 1990s. The few studies undertaken on their effectiveness suggest that in general they have only a moderate controlling effect and that it is rare to find more than 5% of perforated berries parasitized one or more years after releases were made (Barrera, 1994). However a follow-up study seven years after a campaign to rear and release large numbers of C. stephanoderis in different coffee growing areas of Pulney Hills, Tamil Nadu, India, recorded 16-45% parasitism from five different areas (Roobakkumar et al., 2014). Generally low parasitism may be because the berries are harvested before the wasps have a chance to emerge, though more studies are needed to explain their scarcity in the field. Both species parasitize only one berry: the female enters and stays with her brood, rather similar to the borer's maternal behaviour. From the point of view of biocontrol this is unfortunate as a parasitoid that lays eggs in many berries might be more effective. Mass release studies of C. stephanoderis in Colombia and other countries have been carried out but the costs of mass production are uneconomical and likely to remain so because of the high cost of the diet (coffee beans) for the borer host.<br>Phymastichus coffea was seen as a promising biocontrol agent because it attacks adults and thus might help to prevent establishment of the borer in the endosperm, where economic damage is caused. It can also parasitise borers from more than one berry and the few studies on this in the field have suggested that it may be more effective control agent than the bethylids (Baker, 1999). However, to date there are no follow up field studies that suggest it is having any suppressive effect on the borer in the field.<br>The fungus Beauveria bassiana is found naturally wherever H. hampei is present. In humid climates infection may reach more than 50% and is probably the most significant natural control agent of H. hampei. Pascalet (1939) found it prevalent in the forest zone of Cameroon and concluded that conditions favourable to an outbreak were a dense borer population, 20-30°C temperature, sufficient rain to produce the humidity necessary for vigorous sporulation, followed by one or two sunny days to induce an even distribution of spores, followed by light rains to favour development of spores on the bodies of the borers. Intensive efforts in Colombia, Nicaragua, Mexico and Ecuador have been made to develop an effective mycopesticide based on B. bassiana. Results have been very variable with sprays (with varying concentrations of fungal spores/tree) causing anything from 10-86% mortality (Lacayo, 1993;Sponagel, 1994;Bravo, 1995;Bustillo and Posada, 1996;Baker, 1999). High field mortality of H. hampei in the entry canal of the berry (80%+) have been achieved but only at uneconomically high doses. At lower doses the mortality is usually between 20-50% of adult females entering the berry. Further problems relate to the viability and virulence of commercially prepared formulations of the fungus and the product requires careful quality control and monitoring to ensure acceptable standards. Currently in Colombia, despite a concerted research and extension effort over many years, few farmers still apply the fungus. Benavides et al. (2012) suggest that applying a mix of B. bassiana strains may improve virulence. Another approach has been to inject B. bassiana into coffee in the hope that it might establish inside the plant and act as an endophyte to attack the borer when it drills into the berry (Vega et al., 2005).<br>More recently efforts to increase the virulence of Metarhizium anisopliae (a fungus which occasionally attacks H. hampei), by inserting a scorpion toxin gene through genetic engineering (Pava-Ripoll et al., 2008).<br>Vega et al. (2002a) have also studied the presence of Wollbachia in H. hampei, a bacterial infection that may be the cause of its skewed sex ratio. However to date there seems to be no practical way to use this knowledge to devise a novel control method.<br>In general nematodes would be difficult to apply to coffee trees, but might be easier to apply to the ground under the trees where the microclimate might be very suitable for them. The fallen berries under the tree are known to be a very important reservoir of re-infestation and yet difficult to control either by chemicals, fungi or manual collection and experimental releases of parasitoids suggest that few of them attack fallen berries. Hence what is needed is something that could actively search for an infested berry and tunnel its way into the berry to attack the coffee berry borer inside. Lopez-Nuñez of Cenicafé, Colombia, working with Steinernema carpocapsae (All strain), S. glaseri and Heterorhabditis bacteriophora has achieved infection and mortality of H. hampei in laboratory and small-scale field trials (Baker, 1999). Efforts continue to evaluate its performance in larger field trials.<br>In recent years there have been a number of studies to evaluate the effect of bird predation (e.g. Johnson et al., 2010;Karp et al., 2013) which through exclusion cage experiments show significant control effects in heavily infested field conditions. The presence of H. hampei in the diet of some birds has been confirmed through DNA analysis of faecal samples (Karp et al., 2014), however less than 10% of birds tested positive for H. hampei. Exclusion studies have also been carried out with ants (e.g. Solenopsis geminata;Trible and Carroll, 2014) which show a significant predation effect. To date though, no long term field experiments have been performed which demonstrate reliable and significant predation from a range of naturally occurring predators. The main difficulty is that generalist predators tend to search for high density prey and may switch away from H. hampei at levels above an acceptable economic threshold.<br>Thus despite intensive efforts over the last 25 + years, the impact of biocontrol on H. hampei continues to be disappointingly low.
Integrated Pest Management
A crude version of IPM is employed by many farmers, involving some cultural control and insecticidal spraying. Different schemes, based on sampling and economic thresholds have been developed (Decazy and Castro, 1990), but it is difficult to establish simple thresholds on a perennial crop with a prolonged flowering period and a long berry development period. Further, if a chemical control option is selected, it needs to be carried out many weeks (16 or more) before harvest when the borers are in their most susceptible stage (Decazy et al., 1989;Barrera, 1994). Establishment of an economic threshold is equally difficult when the coffee farmer is unsure of the impact of the post-harvest borer population on the next harvest many months hence. Extensive studies of Colombian farmers attest to the difficulty of adoption of complex IPM regimes (Duque and Chaves, 2000). In many cases a value of 5% berries damaged is used as a ‘rule-of-thumb’ action threshold.<br>The main issue is that there is no simple and cheap method to control this insect. This has led to the promotion of a very wide range of combinations of control elements which has sometimes resulted in quite complex IPM schedules that farmers, especially smallholders, find difficult to adopt. It is frequently not clear that each added element exerts a significant or cost-effective increment to control. To an extent this is due to the complex nature of the pest, which is cryptic and may have multiple overlapping populations growing on several populations of berries resulting from different flowerings. This situation demands extensive and multi-year research studies which are frequently beyond the budgets of small research facilities of most coffee countries. The prospects for IPM of H. hampei are dealt with in detail in Baker (1999).

Source: cabi.org
Description

Adult Females
The morphology of adult females was described in detail by Ezzat and McConnell (1956), McKenzie (1967), Entwistle (1972), Cox (1989), Cox and Freeston (1985) and Padi (1990).
The external diagnostic characters include 18 pairs of short, stout wax filaments along margins, of which the anal and two preceding pairs are slightly longer than the rest but less than 20% of body length. Dorsum covered with fine mealy wax with a slightly darker, longitudinal, median stripe from first thoracic to mid-abdominal segments. Body colour beneath wax is usually yellow to peach pink. Antenna 8 segmented. Authoritative identification requires microscopic study of slide-mounted females;Sirisena et al. (2013) provided a method for preparation of slide mounts of adult females.
Body of slide-mounted adult female oval, 1.6-3.2 mm long, 1.2-2.0 mm wide (Cox, 1989). Body margin with 18 pairs of cerarii, each cerarius with two conical setae except for the pre-ocular pair which may have one or three setae each. Legs elongate;hind trochanter + femur 220-350 µm long;hind tibia + tarsus 260-420 µm long. Ratio of hind tibia + tarsus to hind trochanter + femur 1.1-1.3;translucent pores present on hind coxae and tibiae. Circulus quadrate, width 120-200 µm. Cisanal setae shorter than anal ring setae. Anal lobes moderately developed;anal lobe cerarii each situated on a small, moderately sclerotized area;venter of each anal lobe with sclerotized anal lobe bar bearing apical seta and bar seta.
Venter
Multilocular disc pores present around vulva, in single or double rows across posterior edges of abdominal segments III-VII, in single rows across anterior edges of segments V-VII, in marginal groups on abdominal segments IV-VII and sometimes a few pores scattered over median area of the thorax and head, but no more than a total of six pores behind the front coxae. Oral collar tubular ducts of two sizes: smaller ducts in sparse rows across median areas of abdominal segments I-VII;larger ducts in marginal groups of variable size around entire venter including head and thorax, and scattered over median area of thorax.
Dorsum
Multilocular disc pores absent. Tubular ducts without rims, slightly larger than the larger ducts on venter, often adjacent to some cerarii. One or two ducts sometimes present on median areas. Simple pores present of two sizes, smaller pores smaller than the smaller size on the venter, scattered over entire dorsum;larger simple pores, each about twice the size of a trilocular pore, present in small groups along mid-line of thoracic and anterior abdominal segments. Setae short and flagellate, longest seta on abdominal segments VI or VII 30-35 µm long.
Adult Males
Males each have a single pair of wings and no mouthparts. They cannot be authoritatively identified at present. Detailed descriptions of the morphology of the adult male are available in Giliomee (1961), Afifi (1968) and Afifi et al. (1976).

Recognition


Although generally cryptic in nature, P. citri can be easily detected on fruits and inflorescences. On cocoa, it can be readily detected on the surface of pods, where it usually forms large colonies. Colonies in terminal buds, bases of leaf petioles, points of attachment of chupons [suckers], fruits and pods, and the bark of trees can be detected using a hand lens or, in the case of terminal buds, by teasing them apart and inspecting them under a dissecting microscope. On Citrus, the area underneath the calyx and the peduncle of the fruit provides a good hiding place (Meyerdirk et al., 1981). P. citri can also be detected in the field by the presence of ants and sooty moulds that develop on excreted honeydew (Gausman, 1974) and by wilt of plant parts such as leaves, inflorescences and fruits or berries.

Symptons

P. citri feeding leads to general wilting due to sap depletion. On cocoa, flower stalks, buds and young pods are attacked (Entwistle, 1972). In Taiwan, infested immature coffee berries become deformed and drop to the ground (Moriyama, 1941).
P. citri infestation also causes indirect physical damage because sugary honeydew excreted by the mealybugs fouls plant surfaces, giving rise to sooty moulds (Gausman and Hart, 1974) that block light and air from the leaves, inhibiting photosynthesis.
Citrus mealybug is the second most important vector of several strains of Cacao swollen shoot virus;symptoms include leaf chlorosis, root necrosis, root and stem swellings and dieback (Posnette, 1941;Cotterell, 1943).

Impact

Planococcus citri is a highly polyphagous, adaptable mealybug that can feed on many host plants in a variety of conditions, and can reproduce rapidly. It has been reported on over 200 host-plant species belonging to 191 genera and 82 families, and can seriously damage many crops, particularly citrus and glasshouse tomatoes. It is known to transmit some plant virus diseases like Cacaoa swollen shoot virus. The mealybug is of Old World origin, but its polyphagy has facilitated its spread about the world by human transport of infested plants over many years, and it is now established in in all the temperate and tropical zoogeographic regions, and lives under glass in higher latitudes. Its small size and cryptic habits makes it difficult to detect and identify at plant quarantine inspection. The increase in international trade in fresh plant material in recent years is facilitating its continued spread.

Hosts

P. citri is polyphagous and occurs on a wide range of flowering plants, having been recorded on over 200 host species belonging to 191 genera in 82 families (García et al., 2016).
In the tropics, it occurs mainly on the aerial parts of crops such as cocoa, bananas, tobacco and coffee and on wild trees such as Ceiba pentandra and Leucaena (Strickland, 1951a,b;Le Pelley, 1968;Entwistle, 1972). In Ghana, P. citri has been recorded on about 54 host plants, including cocoa, cola, pineapples, Musa paradisiaca and others within the families Bombacaceae, Euphorbiaceae, Fabaceae, Moraceae, Rubiaceae, Solanaceae, Sterculiaceae, Tiliaceae and Urticaceae (Strickland, 1951a;Padi et al., 1999). Hargreaves (1937) cited Anisophyllea laurina as an alternative food plant in Sierra Leone.
In the South Pacific region, P. citri has been recorded on 20 host plants, including Brassica, Ceiba, Citrus, cocoa, Cyrtosperma, Cucurbita, Gardenia, Inocarpus, Ipomoea, Leucaena, Morinda, Ocimum, Psidium, Pueraria and Solanum spp. (Williams and Watson, 1988). Its host plants in Australia include pumpkins in New South Wales;Clerodendrum, Coleus, Croton and Erythrina species in hothouses, and Ceratonia, Siliqua and Veronica species in the open in Adelaide (Brooks, 1957);and pineapples (Carter, 1942), Vitis vinifera and passionfruits in Queensland (Williams, 1973;Murray, 1978b).
In India, P. citri occurs on mandarin orange (Amitava Konar, 1998) and has been recorded for the first time on soyabean (Jadhav et al., 1996).
In temperate regions, P. citri mainly occurs on greenhouse plants such as Coleus, ferns and gardenias, but also occurs outdoors under summer conditions on Citrus, grapes, figs, taro, date palms and potatoes (Bivins and Deal, 1973;Gibson and Turner, 1977). It mainly attacks Citrus but not grapes in the Mediterranean region (Cox, 1989) and California. In the former Soviet Union, it occurs on over 20 species of plants, notably Citrus, figs and pomegranates (Niyazov, 1969). In Turkmenistan, pomegranates are most liable to heavy infestation. It occurs on Areca sp. and a wide range of greenhouse ornamental plants in Korea (Paik, 1972) and Bulgaria (Tsalev, 1970).
In Texas, USA, P. citri has been recorded on the milk vine Cynanchum unifarium [ Cynanchum racemosum var. unifarium ] (French and Reeve, 1978). Host plants in India include Macadamia ternifolia (Wysoki, 1977).


Source: cabi.org
Description

V. velutina is highly variable in colour and 10 subspecies have been identified (https://www.cabi.org/ISC/datasheet/109164#232C47A5-7C02-427F-82E5-D5A688..." Vecht 1957;https://www.cabi.org/ISC/datasheet/109164#2C0D6014-E428-464E-A3BD-5BEF21..." Carpenter and Kojima 1997;https://www.cabi.org/ISC/datasheet/109164#01E52E03-1E70-4BB4-B22D-0D07CD..." Nguyen et al., 2006). The subspecies nigrithorax du Buysson (1905) is invasive in Europe, where it varies in size from 17 to 32 mm (Rome and Villemant, 2018).

Impact

Vespa velutina (Hymenoptera: Vespidae) is a hornet of Asian origin which is a generalist predator of medium- to large-sized insects, and scavenger of vertebrate carrion. It has large impacts on Diptera and social hymenopterans, and in particular on honey bees (Apis spp.). It has recently been spreading in Asia (it is an invasive species in South Korea and Japan), and the subspecies V. v. nigrithorax has been accidentally introduced to Europe where it was first recorded from southern France in 2005. Since then it has been found in Spain, Portugal, Belgium, Italy, the UK, the Netherlands, Germany, the Channel Islands and the Balearic Islands. This invasive species threatens honey production and native pollinating insects. It may be introduced and transported accidentally with soil associated with plants, garden furniture and pots, timber, vegetables, camping equipment, etc.


Source: cabi.org
Description


Annual or short-term perennial, stems 10-60(-120) cm, mostly procumbent. Leaves cauline. Leaves rhombic-ovate to triangular, 1.5-3.5 cm long, 1-3 cm wide, with conspicuous glands on both surfaces, margins irregularly serrate above the middle, base cuneate, petioles 0.3-1.5 cm long. Heads 4-6 mm in diameter, generally solitary, with 3-8 white-cream-yellow ray florets and 3-8 yellowish disc florets functionally staminate. The single-seeded fruits (cypselae) are each enclosed within and shed with an often hardened, ± prickly perigynium, ultimately plumply ellipsoid to fusiform, or ± compressed (PIER, 2015;PROTA, 2015;ZipcodeZoo, 2015).

Impact

Acanthospermum australe is a creeping annual or short-lived perennial plant, which originates from the tropics and sub-tropics of Central and South America. A. australe has been introduced to China, Australia, Africa, and the USA, where it is classed as invasive in the states of Hawaii and Oregon. It spreads to form dense mats that can smother other low-growing vegetation. In Australia, A. australe is seen as a threat to native mat-forming species in coastal sand dunes and in hind-dune vegetation. It is also regarded as an invasive species within its native range in Brazil, where it occurs in conservation areas.


Source: cabi.org
Description

A. craccivora is a relatively small aphid. Apterous viviparous females have a shiny black or dark brown body with a prominent cauda and brown to yellow legs. Immatures are slightly dusted with wax, adults without wax. Six-segmented antennae. Distal part of femur, siphunculi and cauda black. Apterae 1.4-2.2 mm.
Alate viviparous A. craccivora females have abdomens with dorsal cross bars. Alatae 1.4-2.1 mm (Blackman and Eastop, 2000).

Recognition


On groundnut, very young rolled up leaves of seedlings should be examined for nymphs early in the season.

Symptons


Groundnut plants take on a bushy appearance due to attack by A. craccivora and infection with rosette virus. Rosette may take two forms, chlorotic rosette (white patches with green veins on young leaves and short internodes) and green rosette (darker appearance with stunting of leaflets and branches).

Hosts

A. craccivora is polyphagous, but with marked preference for Leguminosae, for example, Caragana, Lupinus, Medicago, Melilotus, Robinia, Trifolium and Vicia. It is found in small colonies on many other families, including Cruciferae.


Source: cabi.org
Description

A. mexicana is an annual herb, up to 150 cm tall with a slightly branched tap root. The stem is erect, branched, usually prickly, pale bluish-green and exudes an unpleasant-smelling yellow sap when cut. Leaves are alternate, without petioles, more or less sheathing the stem, up to 15 cm long, deeply lobed with irregularly toothed, spiny margins;greyish-white veins are conspicuous on the bluish-green upper surface of the leaves. Flowers are solitary, 2.5-4.5 cm in diameter, subtended by 1-2 leafy bracts;sepals 3, prickly;petals 4-6, yellow to pale orange, glabrous;stamens numerous. Fruit is a capsule, spiny, 2.5-5 cm long and 2 cm wide, with 4-6 valves opening at the tip to release numerous seeds. Seeds are brownish-black, nearly spherical, about 1 mm in diameter, covered in a fine network of veins, oily.
A. mexicana forma leiocarpa is a form found in West Africa which has few or no prickles on the stem, leaves and capsule (Lucas, 1962).

Impact

A. mexicana is a widespread annual weed primarily associated with agricultural crops and wastelands. It is a major weed of a number of crops in the tropics and warm temperate regions and is persistent as it produces a seed bank. In India in particular, the species is a health hazard and because of its prickliness, is a nuisance to subsistence farmers. In South Africa the seeds of A. mexicana have been declared as 'noxious' as its seeds or bits of seeds may represent a hazard to human or animal health when consumed (NDA, 2001). It is reported as invasive in many countries in Asia, Africa, the Caribbean and Americas, and Oceania (Australia and a number of Pacific island states).

Hosts

A. mexicana is a weed of most cropping systems, including large- and small-grain cereals, legumes, vegetables, fibre crops (cotton, sisal) and perennial crops (coffee, sugarcane). It appears that any crop has the potential to be infested with A. mexicana if grown within the habitat range of this weed.


Source: cabi.org
Description


The following description is taken from Flora of Pakistan (2015).

Impact

A. ochroleuca is an annual herb native to Central America. It has been introduced into Australia, Africa, tropical Asia, New Zealand and a number of oceanic islands where it has become invasive. It is most common in disturbed areas such as roadsides, mining dumps, rabbit warrens, recently cultivated paddocks, degraded land and over-grazed pastures. This species produces a large number of seed which can be accidentally introduced into new areas as a seed contaminant. It is often a problem in agricultural land but also has the potential to outcompete native species and decrease biodiversity. A. ochroleuca is toxic to humans and livestock and has thorny spines which can cause injury.


Source: cabi.org
Description


Annual herb, to 80 (-150) cm tall. Stems unbranched or more commonly few-branched. Leaves petiolate or distal ones sessile;petioles to 1.5 cm, narrowly winged;blade 1.5-5 × 1-1.5(4) cm, obovate or less often elliptic or ovate, base cuneate, apex acute to obtuse, lower surface pilose, usually glandular. Inflorescence of 5 to numerous heads, 13-20-flowered;involucre 2.5-3 mm long;outer phyllaries much reduced, inner phyllaries subequal. Corolla 3-4 mm, exserted 1.5-2 mm from involucre, the tube long and narrow, 2-3 mm, the limbs short, pilose. Achenes 1.2–2 mm long, subfusiform, terete not ribbed, inner pappus white, exserted from involucre and nearly as long as the corollas (Funk and Pruski, 1996).

Impact

C. cinereum is a cosmopolitan weed common in disturbed areas in tropical and subtropical regions of the world (Randall, 2012). It is a fast-growing, annual herb with the capacity to form dense patches in gardens, roadsides, waste grounds and pasture (Holm et al., 1997). Currently, this species is considered invasive in many islands in the Pacific Ocean (e.g. Hawaii, Fiji, French Polynesia and Micronesia), New Zealand, Singapore, Costa Rica, Guatemala, Nicaragua, Panama, Galápagos Islands, Cuba, Puerto Rico and the Virgin Islands (see distribution table for details;Chong et al., 2009;Chacon and Saborio, 2012;González-Torres et al., 2012;PIER, 2013).

Hosts

C. cinereum is reported as a weed in 27 crops in 47 countries (Holm et al., 1997).
Serious weed in:
sugarcane, cotton, groundnuts and wheat in India
pastures in Australia, India, Nigeria and Thailand
rice in Philippines;
taro in Samoa.
Common weed in:
banana in Surinam and Tonga
cassava in Surinam
cocoa in Indonesia
citrus in Surinam
cotton in the Philippines
maize in India
oil palm in Surinam
pastures in Australia, Dominican Republic, Puerto Rico and Jamaica
pineapple in Hawaii
rice in Surinam, India, Indonesia and Sri Lanka
rubber in Indonesia and Thailand
sugarcane in Bangladesh, Hawaii, and the Philippines
taro in Tonga
tea in India and Indonesia
vegetables in Surinam and Thailand
Unranked weed in:
abaca (Musa textilis) in the Philippines
cocoa in Dominican Republic
cassava in India, Indonesia, and Nigeria
coconut in Sri Lanka and Surinam
coffee in Dominican Republic
cotton in Mozambique and Tanzania
legumes and tomatoes in the Philippines
macadamia nut in Hawaii
maize in Cambodia, Gambia, Indonesia, Nigeria, the Philippines and Zambia
pastures in the Philippines
groundnuts in Indonesia and Nigeria
rice in Laos, Thailand and Vietnam
rubber and tea in Sri Lanka
sugarcane in British Guiana, Dominican Republic, Laos and Vietnam
tobacco in the Philippines
Host Plants and Other Plants Affected
Top of page
Plant name|Family|Context
Ananas comosus (pineapple)|Bromeliaceae
Arachis hypogaea (groundnut)|Fabaceae
Citrus|Rutaceae
Cocos nucifera (coconut)|Arecaceae
Coffea arabica (arabica coffee)|Rubiaceae
Colocasia esculenta (taro)|Araceae
Elaeis guineensis (African oil palm)|Arecaceae
Gossypium (cotton)|Malvaceae
Hevea brasiliensis (rubber)|Euphorbiaceae
Macadamia integrifolia (macadamia nut)|Proteaceae
Manihot esculenta (cassava)|Euphorbiaceae
Musa (banana)|Musaceae
Nicotiana|Solanaceae
Oryza sativa (rice)|Poaceae
Saccharum|Poaceae
Solanum lycopersicum (tomato)|Solanaceae
Theobroma cacao (cocoa)|Malvaceae
Triticum (wheat)|Poaceae
Zea mays (maize)|Poaceae
Growth Stages
Top of page
Flowering stage, Vegetative growing stage
Biology and Ecology
Top of page
Genetics
C. cinereum plants are diploid with a chromosome number of 2 n = 18 (Holm et al., 1997;Pruski 2013).
Reproductive Biology
Flowers in C. cinereum are pollinated by wind. Probably the most common reproduction system in this genus is allogamy with a sporophytic self-incompatibility (Holm et al., 1997;Flora of China Editorial Committee, 2012).
Physiology and Phenology
C. cinereum is an annual herb and under favourable environmental conditions it produces flowers and seeds for many months (Holm et al., 1997;Flora of China Editorial Committee, 2012).
Environmental Requirements
C. cinereum usually grows as a weed, thus it needs full sunlight and moderate water availability to grow. It prefers sandy-loam soils but can be found growing on a range of soils with pH ranging from 4 to 6. It is able to tolerate semiarid conditions as well as partial salinity conditions (PROTA4U, 2013).


Source: cabi.org
Description

D. cordata is a weak prostrate or creeping annual, or less commonly perennial, herb up to 50 cm across or tall, usually with a mass of extensively branched, trailing stems which may root at the nodes.
Roots are fibrous, shallow, mainly from the base of the stem but also from the lower nodes where the soil is moist.
Stems are weak, trailing or ascending, usually extensively branched to form a dense mat in the centre of the plant, smooth and slender, sometimes hairy, with swollen nodes.
Leaves in opposite pairs on slender 3-10 mm long petioles, round to heart-shaped or oval with rounded bases, smooth margins and rounded or bluntly pointed tips, 5-25 mm long and wide, hairless, weakly three-nerved, and paler below. Very short stipules persist at the bases of the petioles.
Flowers in small repeatedly forked terminal or axillary clusters (cymes), on slender, densely hairy, 5-15 mm long pedicels. The flowers consist of five narrow green sepals 2-4 mm long, five, deeply forked, white petals which are shorter than the sepals, and two or three stamens surrounding the deeply divided style. The fruit is a papery capsule 2-3 mm across, splitting at maturity into three parts to release the 5-10 small reddish tuberculate flattened seeds.
The seedlings have epigeal germination. The hypocotyls are slender, erect, and about 5 mm long, the cotyledons resemble the adult leaves, and the first leaves develop in tight clusters in their axils.

Impact

D. cordata is a vigorous fast-growing herb included in the Global Compendium of Weeds (Randall, 2012) and listed as one of the most aggressive weeds invading moist habitats in tropical and subtropical regions of the world (Holm et al., 1997;USDA-ARS, 2014). It is listed as a weed in 31 crops in more than 45 countries within and outside its native distribution range. D. cordata produces large amount of seeds (600 seeds/plants) and also spreads vegetatively rooting from the nodes, which is a trait that enable plants to multiply rapidly and colonize large areas very quickly. It has the potential to harm other plants by smothering them under a solid blanket of leaves and by climbing into the bushes (Holm et al., 1997).

Hosts

D. cordata almost certainly occurs in a much wider range of plantation and vegetable crops than indicated in the host list. It is also a weed in moist lawns, gardens, pastures, roadsides, riverbanks, ditches, around houses, and in all other moist, disturbed, cultivated and uncultivated areas. It is considered to be a weed of 31 crops in more than 45 countries around the world.


Source: cabi.org
Description


Eggs

Recognition


The majority of thrips species are so small and cryptic that, except when present in very large numbers, many inspectors and commercial operators may fail to see them. Adults and larvae are able to hide in concealed places on plants such as beneath plant hairs, within tight buds, enclosed in developing leaves, or underneath the calyx of fruits. Eggs are laid concealed within plant tissues. Casual inspection may thus not reveal the presence of thrips, and even insecticide treatment may be ineffective because the chemical fails to contact the hidden thrips. Effective detection methods have yet to be deployed by most quarantine inspection systems, reliance usually being placed on inspection for feeding damage and simple beating to reveal thrips. However, adult and larval thrips can be extracted from plant material within two or three minutes if a sample is placed in a small Tullgren Funnel using turpentine as an irritant rather than light;the living thrips then run down into a glass tube at the bottom of the funnel where they are readily observed and counted.
Infestation levels in glasshouse crops are usually monitored by means of blue or yellow sticky traps. One shade of blue is particularly attractive to flying adult thrips and is widely used for monitoring the species (Brødsgaard, 1989a). Pheromone lures that attract males and females are now available to increase the sensitivity of monitoring at low levels of infestation or in easily damaged crops (Hamilton et al., 2005). Thrips can also be monitored by extracting thrips from flowers and recording their numbers or the percentage occupancy of flowers (Navas et al., 1994;Steiner and Goodwin, 2005). Western flower thrips adults are easily carried into glasshouses by wind, as well as on the clothes or in the hair of working personnel, thus making re-infestation from surrounding weeds a constant probability. Indeed, weed control around a crop, whether inside a glasshouse or on surrounding land, is the first measure to be adopted in any control strategy. Thrips are also easily carried on equipment and containers that have not been properly cleaned, and infestations in sterile laboratories with filtered air are usually due to thrips being carried in on the clothes and hair of workers. Nationally and internationally, F. occidentalis is readily transported to new areas on all types of planting material as well as on cut flowers, both commercial and domestic (Vierbergen, 1995).

Symptons


The symptoms of infestation by F. occidentalis vary widely among the different plants that are attacked. On roses or gerberas with red flowers, or on dark Saintpaulia flowers, feeding damage is readily visible as white streaking. This type of damage is less apparent on white or yellow flowers, and these commonly tolerate very much higher thrips populations with no visible symptoms. Severe infestation leads to deformation of buds if the feeding occurs before these start opening. Capsicums and cucumbers that have been attacked whilst young, show serious distortions as they mature. Leaf damage is variable, but includes silvering due to necrotic plant cells that have been drained of their contents by thrips feeding, malformation due to uneven growth, and a range of spots and other feeding scars. Eggs laid in petal tissue cause a 'pimpling' effect in flowers such as orchids. Egg laying on sensitive fruits such as table grapes, tomatoes and apples leads to the spotting of the skin of the fruit, which reduces the aesthetic value of the fruit. It can also lead to splitting and subsequent entry of fungi. However, the most serious effect of thrips feeding is due to the transmission of tospoviruses into susceptible crops, such as tomatoes, capsicums, lettuce or Impatiens. At least five different tospoviruses are known to be transmitted by western flower thrips and more may well be discovered: Tomato spotted wilt virus (TSWV), Impatiens necrotic spot virus (INSV), Groundnut ringspot virus (GRSV), Chrysanthemum stem necrosis virus (CSNV) and Tomato chlorotic spot virus (TCSV) (Whitfield et al., 2005). These viruses are acquired by the first-instar or early second-instar larvae when feeding on an infected plant, and are then transmitted only later when these larvae develop into the mobile adults;it is not possible for an adult to acquire and then transmit any of these viruses (Moritz et al., 2004). Virus symptoms vary considerably among plants, ranging from the disastrous wilting and collapse of lettuce plants, through a range of leaf mottling and distortions, to ring-spotting on tomato and capsicum fruits. These virus attacks can lead to the total loss of certain crops (see reviews in Kuo, 1996). F. occidentalis also transmits a carmovirus (Pelargonium flower break virus, PFBV) and may transmit an ilarvirus (Tobacco streak virus, TSV) (Jones, 2005).

Impact


Since the 1970s Frankliniella occidentalis has successfully invaded many countries to become one of the most important agricultural pests of ornamental, vegetable and fruit crops globally. Its invasiveness is largely attributed to the international movement of plant material and insecticide resistance, both of which have combined to foster the rapid spread of the species throughout the world (Kirk and Terry, 2003). Individuals are very small and they reside in concealed places on plants;thus are easily hidden and hard to detect in transported plant material. They reproduce rapidly and are highly polyphagous, breeding on many horticultural crops that are transported around the world.

Hosts

F. occidentalis is a highly polyphagous species with at least 250 plant species from more than 65 families being listed as 'hosts'. Unfortunately, the term 'host plant' is poorly defined in the literature on thrips. Plant species have sometimes been listed as 'hosts' simply because adults have been collected from them. The concept of 'host plant' is best restricted to those plants on which an insect can breed, and for many of the 250 plants from which F. occidentalis has been recorded there is little or no evidence of successful breeding. However, the association of adults with various plants has economic importance when viruliferous adults feed on susceptible plants. In its native range of the western USA, this thrips species can be found in large numbers on a very wide range of native plants, from lowland herbs to alpine shrubs and forbs. As a pest it is found both outdoors and in glasshouses, and it attacks flowers, fruits and leaves of a wide range of cultivated plants. These include apples, apricots, peaches, nectarines and plums, roses, chrysanthemums, carnations, sweet peas, Gladiolus, Impatiens, Gerbera and Ranunculus, peas, tomatoes, capsicums, cucumbers, melons, strawberries, lucerne, grapes and cotton. In northern Europe it is found particularly on glasshouse crops, such as cucumbers, capsicums, chrysanthemums, Gerbera, roses, Saintpaulia and tomatoes. In southern Europe it is extremely damaging to many field crops, including capsicums, tomatoes, strawberries, table grapes and artichokes, and at least in southern Italy, it has become a dominant member of the thrips fauna in wild flowers. Similarly, in Kenya the species has become a dominant member of the wild thrips fauna near agricultural fields. In contrast, in Australia it has not been found breeding on any native plant species. A further complication in considering its pest status is that in some areas this thrips species is an important predator of plant-feeding mites, such as on cotton in California, and it is then regarded as a beneficial (Trichilo and Leigh, 1986).


Source: cabi.org
Description

O. cumana produces leafless flowering stems 40-60 cm high bearing alternate scales less than 1 cm long. Although usually unbranched above ground, multiple stems sometimes arise from a single tubercle below ground. The plant is pale, completely lacking any chlorophyll. The base of the stem, below ground, is normally swollen and tuberous. The inflorescence, occupying up to half the length of the stems carries many acropetally developing flowers, arranged in spikes or racemes, each subtended by a bract 7-12 mm long (without the additional bracteoles present in O. ramosa). The calyx has four free segments, more-or-less bidentate, 7-12 mm long. The white corolla tube, 20-30 mm long, is inflated near the base, conspicuously down-curved, with narrow reflexed lips, up to 10 mm across. The tube is mainly white or pale while the lips are contrastingly blue or purple, without distinct venation. Filaments are inserted in the corolla tube, 4-6 mm above the base. Filaments and anthers hairy. A capsule develops up to 8-10 mm long and may contain several hundred seeds, each about 0.2 x 0.4 mm. A single plant carries 10-100 flowers and hence may produce over 100,000 seeds (Chater and Webb, 1972).

Hosts

O. cumana is often associated with H. annuus and to some wild Helianthus species. Some reports of O. cumana on other wild hosts, including species of Artemisia are presumed to be a misnaming of the more typical O. cernua taxa.

Biological Control
Bedi et al. (1994) investigated the potential of Fusarium oxysporum f. sp. orthoceras isolated from diseases inflorescences of O. cumana in Bulgaria as a potential biocontrol agent. This pathogen has been studied further and has proven to be efficacious under greenhouse conditions when formulated as wheat-kaolin granules (Shabana et al., 2003, Dor et al., 2007). A combination with F. solani (a weak pathogen of O. cumana) isolated in Israel from O. aegyptiaca was found to be synergistic providing more effective control of O. cumana than either agent alone (Dor et al., 2006).;Other potential biocontrol candidates have included Aspergillus alliaceus (Aybeke et al., 2014) and Ulocladium botrytis [ Alternaria botrytis ] (MŸller-Stšver et al., 2005). In spite of this there are no reports of the current use of fungi for biological control in the field.;The one insect to have been extensively studied as a possible biocontrol agent is the dipteran Phyomyza orobanchia which feeds on a number of species of Orobanche (Kroschel and Klein, 1999). In one study in Russia, P. orobanchia was exploited on over 30,000 ha, involving the release of 5-600 adults per ha and was estimated to have reduced seed production by 82-88%. Studies on other species of Orobanche achieved over 90% reduction but only when repeated for 3-4 years. However, since seed production is not completely prevented, the benefits of this agent are dubious. In addition to this P. orobanchia itself is severely affected by the hymenopterous parasites Chalcidoidea and Braconidae (particularly Opius occulisus) and also by Cladosporium cladosporioides and various species of Fusarium (Horv‡th, 1987).;Louarn et al. (2012) have demonstrated that the arbuscular mychorrhizal fungus Rhizophagus irregularis can significantly reduce infestation of sunflower by O. cumana, by directly and indirectly reducing its germination.

Source: cabi.org
Description

R. fistulosa is a broad-leaved, annual, facultative hemi-parasitic forb species found in wetlands in tropical Africa (e.g. Hansen, 1975;Ouédraogo et al., 1999). When these wetlands are used for crop production, the species may develop into a (parasitic) weed (Bouriquet, 1933;Rodenburg et al., 2011b).

Recognition

R. fistulosa is a relatively unknown species at present and therefore it is often unnoticed by local extension and research (as observed in Benin, Cote d’Ivoire, Madagascar, Senegal, Tanzania and Uganda). The species is also easily overlooked as the flowers are only opening at sunset (Cissé et al., 1996).
R. fistulosa can be confused with several species, including Cycnium recurvum (Oliv.) Engl. (previously named R. fistulosa recurva Oliv. and R. tenuisecta Standl.), which has a similar plant type and overlapping distribution in parts of North-East and South-East Africa. However, the tube of the corolla of C. recurvum is about one third of that of R. fistulosa. Moreover, C. recurvum has a distinctly different habitat, favouring dry conditions (Mielcarek, 1996).
The closely-related genera Rhamphicarpa and Cycnium are distinguished by the form of the capsules and the presence of a beak on their capsules: Rhamphicarpa have oblique ovoid capsules with beaks, whereas Cycnium have straight oblong capsules without a beak (Cycnium) (Staner, 1938).
Another distinctive feature is the stamens: Rhamphicarpa stamens are didynamous, arising at 2 levels in the corolla tube, and the style exceeds the stamens, whereas in Cycnium the style never exceeds the lower pair of stamens, and stamens are equal in length, arising at 1 level in the corolla tube (Philcox, 1990;Fischer, 1999;Leistner, 2005).
Due to their parasitic nature, and similarities in host crop ranges, local names given by farmers are often the same for both R. fistulosa and Striga spp. (J Rodenburg, personal observation). R. fistulosa is sometimes even referred to as ‘the Striga of rice’, even though both R. fistulosa and Striga spp. parasitize rice. Striga spp. are usually found on rice grown in the free-draining uplands, whereas R. fistulosa parasitizes rice in the water-logged lowlands and hydromorphic zones.

Impact

R. fistulosa is a broad-leaved, annual, facultative hemi-parasitic forb species very widespread in the wetlands of tropical Africa (Staner, 1938). It has also been reported in India, New Guinea and Australia. No hard evidence is published on the invasiveness of R. fistulosa. Although R. fistulosa is not yet considered to be a widespread problem, it has the potential to become more important in the near future (Raynal Roques, 1994;Rodenburg et al., 2010;2011a), especially since it can develop into a parasitic weed when it encounters a suitable host plant (e.g. Akoegninou et al., 1999). It parasitizes cereal crops like rice and there are indications that it is increasingly common on rain-fed lowland rice (Rodenburg et al., 2011b). Given its very widespread distribution (more than 35 countries in sub-Saharan Africa), the species is likely to be, or become, a very serious parasitic weed, threatening rice production in the continent.

Hosts

R. fistulosa parasitizes wild grass species (of the Poaceae family) and is a facultative hemi-parasitic weed on cereal crops like rice, maize and millet (Bouriquet, 1933;Kuijt, 1969;Cissé et al., 1996;Ouédraogo et al., 1999). Groundnut Arachis hypogaea L. (Bouriquet, 1933) and cowpea Vigna unguiculata (L.) Walp. (Kuijt, 1969) have been reported as hosts too, although the latter report concerned R. veronicaefolio Vatke (= Cycnium veronicifolium Vatke), rather than R. fistulosa (Fuggles-Couchman, 1935).
Rice, particularly direct seeded rice (Johnson et al., 1998), is the most affected crop, as this is the only major cereal crop that can be grown in the temporary flooded conditions of the rain-fed lowlands where R. fistulosa thrives (Rodenburg et al., 2010;2011b).
Supposedly R. fistulosa can also parasitize members of the monocot Cyperaceae as well as the eudicot Leguminosae and Labiatae families (Bouriquet, 1933). It is very unusual for a parasitic plant species to be able to parasitize both monocotyledons and eudicotyledons, and so these reports need to be confirmed.
R. fistulosa is a facultative hemi-parasite and as such it is not dependent on the presence of a host to complete its life cycle. However, the parasite obtains a reproduction advantage from parasitizing a suitable host plant (Ouédraogo et al., 1999;Rodenburg et al., 2011b).


Source: cabi.org
Hosts Sida acuta
Title: Sida acuta
Description


The following information is primarily from Holm et al. (1977), Waterhouse and Norris (1987) and Parsons and Cuthbertson (1992).

Recognition


Recommended resources for identification of S. acuta include PIER (2009), USDA-NRCS (2009), Viarouge et al. (1997), and Ivens (1968).

Impact


Originating in central America, the small perennial shrub, S. acuta has successfully invaded the tropics worldwide, largely as a contaminant in pasture seed. Its tolerance of a wide range of growing conditions has enabled S. acuta to become established in these diverse habitats. It infests various crops and habitats, but has been most problematic in pastures and rangelands, particularly in savannah-type biomes with pronounced wet and dry seasons. It can form dense monospecific stands in these regions, and has had a pronounced economic impact in northern Australia, Papua New Guinea and many Pacific Islands. Since the late 1980s, the foliage-feeding chrysomelid beetle Calligrapha pantherina has been introduced into many areas as a biological control agent specific to S. acuta and related Sida species. Introductions of C. pantherina have led to successes in control of S. acuta infestations, reducing seed production, and resulting in restoration of native vegetation in many cases.

Hosts

S. acuta is a weed of plantation crops, cereals, root crops and vegetables throughout the Pacific and South-East Asia. It is a principal weed of maize in Mexico, sorghum in Australia and Thailand, tomatoes in the Philippines, onions in Brazil, and pastures in Australia, Fiji, Nigeria and Papua New Guinea. It is also a weed of tea in Taiwan and Sri Lanka, groundnuts in Ghana, cassava in Ghana and Nigeria, maize in Ghana, Nigeria and Thailand, coconuts in Trinidad, beans in Brazil, pastures under coconuts in Sri Lanka, pineapples in the Philippines, sugarcane and groundnuts in Australia, El Salvador and Trinidad, coffee in Colombia, rubber in Malaysia, upland rice in the Philippines and Nigeria, cotton in El Salvador and Thailand, and cowpeas and sweet potatoes in Nigeria (Holm et al., 1977;Chadhokar, 1978;Mott, 1980;Parsons and Cuthbertson, 1992;Ham and Eastick, 2004).


Source: cabi.org
Title: Sida acuta
Description

In culture (PDA medium, 39 g/l), colonies are circular-radial, flat, greyish-brown and have a growth rate of 5.3 mm/day at 25 ± 1°C in the dark (Astiz Gassó and Marinelii, 2003;2013). The mycelium is branched and septate, typical of basidiomycetes. Teliospores are reddish brown and can differ in size depending on the number of cells. A single cell spore is 20 μm, whereas spores composed of eight cells can be 50 μm in size (Marraro Acuña et al., 2013;Rago et al., 2017).

Recognition

Symptoms of the disease are characteristic and easy to identify in the field. As the aerial part of the plant is asymptomatic, it is necessary to open pods at advanced stages of development to detect the pathogen (Rago et al., 2017). Disease assessment is performed when a given field is to be harvested of mature pods (R8). It is only in this phenological state that it is possible to estimate the severity of the disease in samples. Infection can be seen in immature pods, but it is difficult to estimate severity. One of the tools for monitoring the disease is based on the quantification of spores in the plot to be planted. This is done through sampling and observing soil suspensions under the microscope. Oddino et al. (2010) related the amount of inoculum present in a plot with the incidence of the disease.

Symptons

Infection is localized and infected plants do not exhibit aerial symptoms. Affected pods exhibit hypertrophy and have a spongy consistency, and kernels can be replaced, partially or totally, by a reddish-brown mass of spores.

Impact

Thecaphora frezii is the causal agent of peanut smut. The disease was first reported in 1962 in wild peanuts from Aquidauana, Mato Grosso do Sul, Brazil. It was first detected in commercial crops in 1995 in the central-northern area of Córdoba province, Argentina. The prevalence of peanut smut has gradually increased. In the 2011/12 growing season, the disease was found in all production fields in Córdoba province and, two years later, it was found in all peanut production areas of Argentina. The increase in the intensity of peanut smut in Argentina has been accompanied by increasing yield losses.

Hosts

Arachis is the only host reported for T. frezii (Rago et al., 2017). The disease has been reported in commercial peanut crops in Argentina, but only occurs in wild peanuts in Brazil and Bolivia (Carranza and Lindquist, 1962;Soave et al., 2014). All of the peanut cultivars that are widely planted in Argentina are susceptible (Cignetti et al., 2010a).

Biological Control
There are few records of field trials using biological control against T. frezii, but it could offer some level of disease reduction. A bioformulation based on Trichoderma harzianum provided a 24% reduction in incidence and 25% reduction in the severity of the disease (Pastor et al., 2015;Ganuza et al., 2018a,b).

Source: cabi.org
Description

U. platyphylla is an annual grass. Culms 25-100 cm, decumbent, rooting at the lower nodes;nodes glabrous. Sheaths glabrous or sparsely pilose;ligules 0.5-1 mm;blades 2.5-17.5 cm long, 3-13 mm wide, glabrous or sparsely pilose, bases subcordate, not clasping the stems, margins ciliate basally, with papillose-based hairs. Panicles 6-16 cm long, 2-2.5 cm wide, with 2-8 spike-like primary branches in 2 ranks;primary branches 3-8 cm, axils pubescent, axes 1.3-2.5 mm wide, flat, usually glabrous, occasionally pilose dorsally;secondary branches rarely present;pedicels shorter than the spikelets, scabrous and sparsely pilose. Spikelets 3.8-5 mm long, 2-2.5 mm wide, ovoid, bi-convex;solitary, appressed to the branches, in 2 rows. Glumes scarcely separated;lower glumes 1.2-1.8 mm, to 1/3 as long as the spikelets, obtuse, glabrous, 5(-7)-veined, not clasping the base of the spikelets;upper glumes 3.2-4.7 mm, glabrous, 7(-9)-veined;lower florets sterile;lower lemmas 3.2-4.7 mm, glabrous, 5-veined;lower paleas present;upper lemmas 2.8-3.4 mm long, 1.8-2.3 mm wide, apices incurved, broadly acute to rounded, mucronulate;anthers about 1 mm. Caryopses 1.5-2.2 mm (Wipff and Thompson, 2003).

Impact

U. platyphylla is a weedy grass species commonly found in disturbed, open and sandy sites such as crop fields, ditches and roadsides. It is considered a troublesome weed because of its tolerance to some herbicides principally in maize plantations (Chamblee et al., 1982;Gallaher et al.,1999). U. platyphylla is highly adaptable and it is able to germinate and grow throughout a wide range of soil and environmental conditions (Burke et al., 2003). Additionally, its seeds may remain on the crop residue until pre-emergence herbicides are no longer effective in controlling the germinating seeds, at which time the seeds fall to the soil surface and germinate (Alford et al., 2005).

Hosts

U. platyphylla grows as a weed in maize, groundnuts, rice, soyabean and citrus plantations where it has been documented to reduce yield (Futch and Hall, 2004;Alford et al., 2005;Sesto et al., 2011).


Source: cabi.org
Description


Although somewhat variable in size and coloration, adult specimens of H. halys range from 12 to 17 mm in length, and in humeral width of 7 to 10 mm. The common name brown marmorated stink bug is a reference to its generally brownish and marbled or mottled dorsal coloration, with dense punctation. Detailed redescriptions and diagnoses of adults are provided by Hoebeke and Carter (2003) and Wyniger and Kment (2010). Eggs are smooth and pale in colour, approximately 1.3 mm in diameter by 1.6 mm in length, and are laid in clusters of 20-30. The brightly coloured, black and reddish-orange first instars remain clustered about the egg mass after hatching and move away once moulting to second instars has occurred. There are five nymphal instars, which are described in Hoebeke and Carter (2003) with a key and illustrated with colour photos.

Recognition

H. halys adults can be detected throughout the active growing season using blacklight traps and baited pheromone traps and nymphal populations can be detected with pheromone traps. However, each trap has limitations. Blacklight traps are attractive from early spring through September with reduced attractiveness as adults begin seeking overwintering sites. Baited pheromone trap effectiveness depends on the lure deployed. The use of methyl (2 E,4 E,6 Z)-decatrienoate only provides late season adult attractivess, whereas the use of (3 S,6 S,7 R,10 S)-10,11-epoxy-1-bisabolen-3-ol and (3 R,6 S,7 R,10 S)-10,11-epoxy-1-bisabolen-3-ol alone or in combination with methyl (2 E,4 E,6 Z)-decatrienoate provides season-long adult attractiveness.
In cropping systems, H. halys adults and nymphs can be detected through the use of timed visual counts, whole plant inspections, beat sheets counts and sweep netting. Timed visual counts are effective in field maize, nursery, nut, tree fruit and vegetable crops. Whole plant inspections are possible in various vegetables, field and sweetcorn by inspecting a specified number of plants per field or through the use of counts per linear foot of row. Beat sheet counts can be employed in nursery, nut and tree fruit;however, they are discouraged in nuts and tree fruit after thinning or June drop has occurred due to the potential removal of fruit. Sweep netting can be used in soyabeans but should be confined to field borders.
H. halys adults seek concealed, cool, tight and dry locations to overwinter. Because of this overwintering behaviour and need for specific microhabitats, many suitable sites can be generated by human-made materials and used by this insect as an overwintering sites such as inside cardboard boxes, other shipping containers and luggage, between wooden boards, within layers of folded tarps, and within machinery motors and vehicles. Thus, inspection for H. halys in shipments of goods from areas where it is present will require thorough visual inspections.

Symptons


Adults and nymphs cause feeding damage. On tree fruits, feeding injury causes depressed or sunken areas that may become 'cat-faced' as the fruit develops. Late season injury causes corky spots on the fruit. Feeding may also cause fruiting structures to abort prematurely. Similar damage occurs in fruiting vegetables such as tomatoes and peppers, although frequently later in the season. Feeding can cause failure of seeds to develop in crops such as maize or soyabean. There is frequently a distinct edge effect in crop plots as H. halys has an aggregated dispersion and moves between crops or woodlots. In soyabeans, this can result in a 'stay green' effect where pods fail to senesce at the edges due to H. halys feeding injury.

Impact


Following the accidental introduction and initial discovery of H. halys in Allentown, Pennsylvania, USA, this species has been detected in 41 states and the District of Columbia in the USA. Isolated populations also exist in Switzerland, France, Italy and Canada. Recent detections also have been reported in Germany and Liechtenstein. BMSB has become a major nuisance pest in the mid-Atlantic region and Pacific Northwest, USA, due to its overwintering behaviour of entering human-made structures in large numbers. BMSB also feeds on numerous tree fruits, vegetables, field crops, ornamental plants, and native vegetation in its native and invaded ranges. In the mid-Atlantic region, serious crop losses have been reported for apples, peaches, sweetcorn, peppers, tomatoes and row crops such as field maize and soyabeans since 2010. Crop damage has also been detected in other states recently including Oregon, Ohio, New York, North Carolina and Tennessee.

Hosts

H. halys has over 100 reported host plants. It is widely considered to be an arboreal species and can frequently be found among woodlots. Such host plants are important for development as well as supporting populations, particularly during the initial spread into a region. In Canada for example, established populations of H. halys have only been recorded in the Province of Ontario. Homeowner finds have previously been identified in the City of Hamilton (Fogain and Graff, 2011) as well as the Greater Toronto Area, the City of Windsor, Newboro and Cedar Springs (Ontario) (Fraser and Gariepy, unpublished data). However, preliminary surveys confirmed an established breeding population in Hamilton, Ontario, as of July 2012 (Fraser and Gariepy, unpublished data). At present, these populations are localized along the top of the Niagara escarpment in urban/natural habitats within Hamilton, and have not yet been recorded in agricultural crops. Reproductive hosts from which H. halys eggs, nymphs and adults have been collected on in Ontario include: ash, buckthorn, catalpa, choke cherry, crabapple, dogwood, high bush cranberry, honeysuckle, lilac, linden, Manitoba maple, mulberry, rose, tree of heaven, walnut and wild grape (Gariepy et al., unpublished data).
The list of host plants in Europe contains 51 species in 32 families, including many exotic and native plants. High densities of nymphs and adults were observed on Catalpa bignonioides, Sorbus aucuparia, Cornus sanguinea, Fraxinus excelsior and Parthenocissus quinquefolia (Haye et al., unpublished data).
Multiple host plants seem to be important for development and survival of H. halys. This species can complete its development entirely on paulownia (Paulownia tomentosa), tree of heaven (Ailanthus altissima), English holly and peach. More details on host plants and host plant utilization can be found at http://www.stopbmsb.org/where-is-bmsb/host-plants/ as well as http://www.halyomorphahalys.com, Panizzi (1997), Nielsen and Hamilton (2009b) and Lee et al. (2013a).
In Asia, H. halys is an occasional outbreak pest of tree fruit (Funayama, 2002). Damage to apples and pears in the USA was first detected in Allentown, Pennsylvania, and Pittstown, New Jersey (Nielsen and Hamilton, 2009a). In orchards where H. halys is established in the USA, it quickly becomes the predominant stink bug species and, unlike native stink bugs, is a season-long pest of tree fruit (Nielsen and Hamilton, 2009a;Leskey et al., 2012a). In particular, peaches, nectarines, apples and Asian pears are heavily attacked. Feeding injury causes depressed or sunken areas that may become cat-faced as fruit develops. Late season injury causes corky spots on the fruit. Feeding may also cause fruiting structures to abort prematurely. Similar damage occurs in fruiting vegetables such as tomatoes and peppers, although frequently later in the season. Feeding can cause failure of seeds to develop in crops such as maize or soyabean. There is frequently a distinct edge effect in crop plots as H. halys an aggregated dispersion and moves between crops or woodlots. In soyabeans, this can result in a 'stay green' effect where pods fail to senesce at the edges due to H. halys feeding injury.


Source: cabi.org
Description

A. raddianum is a fern with a short-creeping and irregularly-branched rhizome up to 50 mm long and ca 2 mm wide. The rhizome and the bases of the frond stalks are covered with dark-brown scales of less than 1 mm length. Fronds are arched to erect, 10-50 cm long and 6-20 cm wide, and triangular in shape. Frond stalks and axes are dark reddish-brown to blackish and shining. The frond stalk is usually longer than the lamina. Laminas are 3-4-pinnately divided, with the ultimate segments delicate, herbaceous and up to 1 cm wide. Ultimate segments are wedge-shaped and have slender red-black stalks. Segments of sterile fronds, if present, are larger than fertile fronds. Spore cases (sori) are 'U'-shaped and arranged either at the edge of veins or at their tips and less than 4 mm wide. Each sorus is covered with a pale or whitish membrane (indusium).

Impact

A. raddianum is a delicate fern native to tropical and subtropical South America. The fern grows terrestrially or on rocks and erects arching fronds, up to 50 cm high, growing out of a short rhizome. The plant has become naturalized in various tropical and subtropical islands and is considered to be invasive in Hawaii and French Polynesia. The fern readily spreads and becomes locally abundant. In Hawaii it was first observed around 1910 and is now the most common Adiantum species. It grows best in moist and shady places and appears to replace the closely related native Adiantum capillus-veneris. It also threatens an endemic species of silversword, Dubautia plantaginea subsp. humilis, and another native fern, Pteris lidgatei.


Source: cabi.org
Description


Decumbent or ascending glabrate aquatic perennials, the simple or branched, often fistulose stems to 100 cm. long. Leaves glabrous or glabrate, lanceolate to narrowly obovate, apically rounded to acute, basally cuneate, rarely denticulate, 2-10 cm. long, 0.5-2 cm. broad;petioles 1-3 mm. long. Inflorescences of terminal and occasionally axillary white glomes, 10-18 mm. long, 10-18 mm. broad, the usually unbranched peduncles 1-5 cm. long. Flowers perfect, bracts and bracteoles subequal, ovate, acuminate, 1-2 mm. long;sepals 5, subequal, oblong, apically acute and occasionally denticulate, neither indurate nor ribbed, 5-6 mm. long, 1.5-2.5 mm. broad;stamens 5, united below into a tube, the pseudostaminodia lacerate and exceeding the anthers;ovary reniform, the style about twice as long as the globose capitate stigma. Fruit an indehiscent reniform utricle 1 mm. long, 1-1.5 mm. broad (Flora of Panama, 2016).

Impact

A. philoxeroides is one of the worst weeds in the world because it invades both terrestrial and aquatic habitats. The aquatic form of the plant has the potential to become a serious threat to rivers, waterways, wetlands and irrigation systems. The terrestrial form grows forming dense mats with a massive underground rhizomatous root system (ISSG, 2016). This weed is extremely difficult to control, is able to reproduce from plant fragments and grows in a wide range of climates and habitats, including terrestrial areas. In aquatic habitats it has deleterious effects on other plants and animals, water quality, aesthetics, vector populations, water flow, flooding and sedimentation. In terrestrial situations, it degrades riverbanks, pastures, and agricultural lands producing massive underground lignified root systems penetrating up to 50-60 cm deep. Currently, A. philoxeroides is listed as invasive in the United States, Puerto Rico, France, Italy, India, Sri Lanka, China, Taiwan, Indonesia, Myanmar, Singapore, Australia and New Zealand (Weber et al., 2008;Chandra, 2012;Rojas-Sandoval and Acevedo-Rodriguez, 2015;DAISIE, 2016;USDA-ARS, 2016;USDA-NRCS, 2016;Weeds of Australia, 2016). Once established, it behaves as an aggressive invader with the capability to totally disrupt natural aquatic ecosystems, shoreline vegetation and terrestrial and semi-aquatic environments (ISSG, 2016;USDA-NRCS, 2016).

Hosts

A. philoxeroides primarily affects floating aquatic plants and pastures but submerged and emerged aquatic plants are also affected.


Source: cabi.org
Description


Adapted from Flora Zambesiaca (2014)

Impact

C. asiatica is a low-growing perennial with a pan-tropical distribution. It can spread to form a dense ground cover, desirable in some situations but unwelcome in others. It is recorded as invasive in a number of Pacific islands to which it has been introduced and is classed as High Risk (score 7) by PIER (2014), but the situations in which it is causing problems are not clear. It is not especially competitive in crops but may affect wild vegetation and biodiversity. C. asiatica is also among a number of species invasive in the Dongting Lake wetlands, Hunan province, China (Hou et al., 2011).

Hosts

C. asiatica is recorded as a weed in rice paddies, various plantation crops and forestry, but there are no indications of serious crop loss due to C. asiatica. Where it is listed as invasive, some native species are being impacted but little detail has been seen. In Hawaii, C. asiatica is among introduced species which have contributed to the decline of native sedges Carex thunbergii and Carex echinata (University of Hawaii, 1991).


Source: cabi.org
Description

C. crepidioides is an erect, sparingly branched aromatic annual herb, 40-100 cm tall. Stem rather stout, soft, ribbed, apically with short, thick hairs, lower down glabrescent;branches densely pubescent. Leaves helically arranged, elliptic, oblong or obovate-elliptic, acute or acuminate, pinnately lobed or pinnatifid, irregularly serrate, very thinly pubescent or glabrous, 8-18 x 2-5.5 cm;base tapered and often long-decurrent into the petiole;uppermost leaves smaller, sessile. Heads in terminal, rather small corymbs, homogamous, many-flowered, cylindrical, 13-16 x 5-6 mm, nodding during anthesis, afterwards erect;bracts linear, 0.5-10 cm long, peduncles densely pubescent;outer involucral bracts free, linear, 1-4 mm long, unequal, inner ones subequal, 1-2 seriate, green with dark-brown, acute, papillose tops, lanceolate, 8-12 mm long, thinly hairy, erect during anthesis, pellucid-marginate, cohering into a cylindrical tube, ultimately spreading, reflexed;hypanthium flat, epaleate, alveolate, alveoles with membranous rim. Flowers equal, bisexual;corolla yellow throughout, 9-11 mm long, tubular;tube long, very slender, funnel-shaped, circa 1 mm long, 5-fid limb. Anthers with entire or shallowly incised base, purple, apex acute. Style bifid, arms long, thin, their truncate, more or less penicilliate top tipped by a subulate appendix. Achenes cylindric-linear, ribbed, dark-brown with paler base and apex, thinly pubescent, 2 mm long;pappus hairs numerous, thin, silky, minutely toothed, white, caducous, 9-10 mm long (Kostermans et al., 1987).

Impact

C. crepidiodes is an invasive herb included in the Global Compendium of Weeds and classified as one of the most aggressive weeds occurring in tropical and subtropical regions (Randall, 2012). It is a pioneer species with the capability to produce large amounts of hairy wind-dispersed seeds. However, Chen et al. (2009) suggest that seed dispersal ability is limited. Chen et al. (2009) report that the species has only a moderate invasive capacity and that its wide distribution in China possibly correlates with its cultivation.

Hosts

C. crepidioides may be found infesting young tea plantations (Sastroutomo and Pandegirot, 1988), in rice, taro, coffee, citrus, sweet potatoes, vegetable crops, orchards and pastures.


Source: cabi.org
Description

The following description comes from Burger and Huft (1995)

Impact

C. argenteus is an herbaceous weed of open sunny sites, pastures, and agricultural lands. It is also a common weed in rice plantations (González, 2000). Because this species grows in seasonally waterlogged areas, its seeds are often dispersed as a contaminant in dried and wet mud (Standley and Steyermark, 1946). Currently, it is listed as invasive only in Cuba, but it is a common weed in dry and wet fields in areas within and outside its native distribution range (Oviedo Prieto et al., 2012;USDA-NRCS, 2015).

Hosts

C. argenteus is a weed of pastures and rice and sugarcane plantations (Standley and Steyermark, 1946;González, 2000;Torres et al., 2010).


Source: cabi.org
Description


Annual herb to subshrub, many branched, erect to sprawling, 10-60 cm tall. Stem viscid-pilose, with intermixed glandular and non-glandular hairs. Leaves opposite, subsessile to short petiolate, elliptic, oval ovate, rarely obovate, with acute apex, 1.5-6 cm long. Flowers arising from leaf axils, solitary, 4.5-7 mm long, floral tube sparsely pubescent with glandular hairs, green, calyx lobes unequal, deltoid, short bristle-tipped, 6 petals, 2-3 mm long, linear-elliptic, pale purple, stamens longer than the floral tube. 3 seeds, 2 mm long, lenticular, olive to brown with pale edges (Graham, 1975).

Impact

Cuphea carthagenensis is an annual herb of moist habitats. Although its native range is uncertain, it is likely to cover parts of Central America and the Caribbean, and South America. It has become naturalized widely outside of its native range, in Central America, North America, the Caribbean, Oceania, and Asia. In its native and introduced range it is a weed of cultivated lands and disturbed sites, and sometimes invades intact natural areas in low densities. In Indonesia, where it dominates maize (Zea Mays), it is considered one of the top ten weeds (Solfiyeni et al., 2013). Several other species of Cuphea are also recorded as invasive (e.g. PIER, 2015).

Hosts

C. carthagenensis has been listed as a weed of a number of agricultural crops. In its native range in Brazil it is considered one of the most important weeds by (Pio, 1980) because of its abundance and competitive effects in Brazilian state of São Paulo, but which crops were affected were not specified. In Hawaii, USA, C. carthagenensis is a weed of cucumber (Cucumis sativus) (Valenzuela et al., 1994). In Assam, India, it is a dominant weed of rice (Oryza sativa) (Randhawa et al., 2006). In Indonesia, it dominates corn (Zea Mays) plantings (Solfiyeni et al., 2013). On Vanuatu, it is a serious pest of coconut (Cocos nucifera) groves and in pastures (Mullen, 2009). It is also a weed of taro (Colocasia esculenta) in Fiji (Heap, 2015) and of pastures (Robert, 1970). Laca-Buendia et al. (1989) reported it to be a sporadic weed of common bean (Phaseolus vulgaris) in Brazil.


Source: cabi.org
Description


Erect subshrub to 1 m tall, with strong, fetid smell, many-branched from a woody base;stem ribbed to cylindrical, more or less pubescent. Leaf blades 2-9 × 0.6-3.8 cm, chartaceous, lanceolate or oblanceolate, glabrous or nearly so, lower surface with abundant yellowish gland dots, the apex obtuse or acute, the base tapering into a more or less elongate (to 2 cm), winged petiole, the margins deeply lobed or serrate to entire on upper leaves. Flowers minute, greenish, in axillary glomerules or in spikes of glomerules, the spikes 1-2 cm long. Calyx greenish, ca. 1 mm long, the sepals oblong;stamens ca. 1 mm long;styles 3, whitish. Utricle whitish, ca. 1 mm long, covered with persistent sepals. Seeds 1 mm long, nearly lenticular, reddish brown (Acevedo-Rodríguez, 2005).

Impact

D. ambrosioides is a herb considered a cosmopolitan weed (Correa et al., 2004). It produces thousands of small seeds that can be easily dispersed by human activities (seed contamination, mud, and farming machinery), as well as by abiotic factors (USDA-ARS, 2013). Once established in new areas, it grows as a weed affecting agriculture and native vegetation (Jellen et al., 2011). D. ambrosioides is one of the most successful herbs colonizing both disturbed and agricultural areas in almost all continents. It is included in the Global Compendium of Weeds where it is listed as a noxious weed in the United States, Central and South America, Asia, Africa, Australia and Europe (Randall, 2012). This species is considered invasive in a wide range of environments including areas in Australia, islands in the Pacific Ocean, Spain, Italy, Greece, China, Vietnam, Cambodia, and South Africa (see distribution table for details: DAISIE, 2013;PIER, 2013;USDA-NRCS, 2013).

Hosts

D. ambrosioides has been reported as a weed affecting crops such as cotton, coffee, beans, chickpeas, maize, rice and grapes (Vibrans, 2011). Additionally, D. ambrosioides is host of the fungal pathogen Erysiphe betae (powdery mildew) which can spread to tomato crops (Prota4U, 2013).


Source: cabi.org
Description


A robust, rhizomatous, reedlike perennial, erect to 3 or 4 m high, along the edges of water, but also developing spongy horizontal stems spreading for many meters across the water surface, or open mud, rooting at the nodes. Leaves up to 60 cm long, 2 cm wide, glabrous when growing in the water, but erect plants can have sharp, irritating hairs on the leaf and sheath. Ligule a line of hairs. Inflorescence green or purplish, up to 30 cm long with many overlapping racemes up to 10 cm long, simple or branched. Spikelets elliptic, plump, 3–4 mm long, glabrous or shortly hairy, with longer hairs on the veins. Upper glume as long as the spikelet;lower glume less than half as long. Lower lemma awnless or with an occasional awn up to 1 or 2 mm long. Upper glume 2–3 mm. (Mainly from Chippindall 1955;Clayton and Renvoize 1982;and Clayton 1989).

Recognition


Preliminary work is reported from Kenya, to identify and survey E. pyramidalis by satellite imagery (Schmidt and Skidmore, 2001).

Impact

E. pyramidalis, a perennial grass, has decidedly invasive characteristics with its vigorous shoot and rhizome growth and abundant seed production. As an aquatic, it also has the potential to be very damaging to sensitive aquatic habitats. Holm et al. (1979) record it as a major weed in its native area in Nigeria, Swaziland, Sudan and Madagascar. In Guyana, after being introduced and cultivated for some years, it was noticed as a weed in sugar cane in 1982 and increased rapidly to become one of the most troublesome weeds in the aquatic system of the Guyana Sugar Corporation (Bishundial et al., 1997). In Mexico, again after introduction as a fodder grass, it has become widely invasive in wetlands, tending to reduce native wetland species (López Rosas et al., 2010). Apart from its competitive growth, Wells et al. (1986) note its tendency to obstruct water flow. For the USA it is highly ranked as a potential invasive weed of the future (Parker et al., 2007) and it has been identified as a species ‘not authorized (for introduction) pending pest risk analysis’ (NAPPRA) (USDA-APHIS, 2012).

Hosts

E. pyramidalis is considered a weed in the rice fields of Australia, India, Philippines, and tropical America (Pancho, 1991;López Rosas, 2007) and also in Africa (e.g. Kent et al., 2001). Other irrigated crops such as sugar cane are also affected directly or indirectly as a result of E. pyramidalis infesting irrigation channels, restricting water flow and/or encroaching into the crop (Bushundial et al., 1991;Bishundial et al., 1997).


Source: cabi.org
Description

E. paniculata usually grows as an annual or short-lived perennial plant. It is rooted in mud in shallow waterways. Submersed sessile leaves form a basal rosette and are linear to oblanceolate. Petiolate leaves are above the water surface with a cordate blade, acuminate to acute at the tip. Petiolate leaf blades grow 7.5-15 cm long, 3.5 – 9 cm wide, and the petiole may be up to 60 cm long. The flowers grow on separate flowering stalks in a panicle with 5-100 flowers developing over several days. The peduncle is sparsely glandular-pubescent to glabrous, 11.5-17.5 cm long;spathe linear, 13-35 mm long, the apex acuminate. Flowers are blue, white or lilac. The floral tube is 8-10 mm long, tepals are 12-15 mm long. The central upper tepal has two yellow spots toward the base. Upper and lower stamens are 2.5-3.5 mm and 5.1-8.5 mm long respectively. Stigmas are 3-lobed and tristylous. Seeds form in capsules 6-8mm long. Seeds are 0.6-1.0 mm long, 0.6-0.8 mm wide with 10-12 longitudinal wings (Barrett and Husband, 1997;Flora of the Guianas, 2016).

Impact

Eichhornia paniculata can grow in monocultural stands in shallow wetlands (Barrett and Husband, 1997). It is listed as a transformative species in Cuba by Oviedo-Prieto et al. (2012), although other sources suggest that it is native to Cuba (FreshFromFlorida, 2016). Listed as a prohibited aquatic plant in Florida along with all species of Eichhornia (USDA-NRCS, 2016), because of the invasive nature of other species in the genus. It appears to have naturalized only in Guyana (Funk et al., 1997) and is listed as an agricultural weed of rice fields in Jamaica and Cuba (Barrett, 2011).

Hosts

A weed of rice fields in Jamaica and Cuba (Barrett, 2011).


Source: cabi.org
Description

E. fosbergii is an annual, erect or ascending herb, branched, 20 to 50 cm (up to 100 cm) tall. Stems glabrous to sparsely pilose or sometimes prominently villous-pilose near the axils of the middle cauline leaves. Leaves alternate, broadly ovate to oblanceolate, often tapering to a prominently winged petiole and therefore appearing pandurate, the base sessile to auriculate, the margin weakly serrate to dentate or sometimes lobed, the teeth callose-tipped, overall 5-10 cm long, 2-5 cm wide, about 2 times longer than wide, the uppermost leaves reduced to linear serrate clasping bracts. Inflorescence of one to several headed, loose, corymbiform cymes arising terminally or laterally in the axils of the upper cauline leaves. Heads turbinate or sometimes weakly urceolate or becoming weakly campanulate in age, robust, 2-3 times longer than wide, the florets prominently exserted approximately 2 mm beyond the involucre;involucral bracts 8-13, linear, (7-) 9-12 mm long;receptacle flat to convex, the carpopodia forming prominent tubercles after achenes have been shed;florets 15-30, varying greatly in size with the robustness of the plant, the corollas pink to light purple or red but not orange. Achene reddish brown to light tan, columnar, approximately 5 mm long with a row of strigose-hirsute pubescence on each of the 5 prominent ribs;pappus of abundant, white, capillary hairs (Flora of Taiwan Editorial Committee, 2014;Missouri Botanical Garden, 2014).

Impact

E. fosbergii is a cosmopolitan annual herb included in the Global Compendium of Weeds (Randall, 2012). It is fast-growing, with the capacity to grow as a weed and colonize disturbed areas, waste ground, gardens, abandoned farmland, coastal forests, forest edges, pastures, roadsides, rocky areas, and riverbanks (Wagner et al., 1999;Vibrans, 2011;Pruski 2014). It produces large amounts of wind-dispersed seeds (5000 seeds per plant;Mejía et al., 1994) which is a feature facilitating the likelihood of spreading and colonizing new habitats. Currently, E. fosbergii is listed as invasive in Mexico, Central America, West Indies, and on several islands in the Pacific Ocean (see Distribution Table for details).

Hosts

E. fosbergii has been listed as a weed in rice plantations in Colombia and coffee plantations in Costa Rica. It is also listed as a weed in cassava and sugarcane plantations in Central and South America (Echegoyen-Ramos et al., 1996, Murillo et al., 2006;Vibrans, 2011).


Source: cabi.org
Description

G. spilanthoides is an aquatic perennial that can form rounded bushes up to 1-1.5 m tall or scrambling mats of tangled stems. The plant can grow in various forms, producing runners and floating stems up to 2.5 m in length or growing as rounded bushes or extending from the banks, in mats of tangled stems reproducing vegetatively and by seed (Csurhes and Edwards, 1998). The following description is from Parsons and Cuthbertson (1992).

Impact

G. spilanthoides is an emergent freshwater or marsh-growing perennial which can form rounded bushes up to 1-1.5 m tall or scrambling mats of tangled stems along the edges of waterways. It grows very rapidly, up to 15 cm per week, and floating mats cover water bodies, blocking drainage channels and degrading natural wetlands by displacing native plants and animals as well as detracting from their environmental value, natural beauty and recreational potential. In New Zealand, it has caused flooding by blocking streams and drainage channels, and it could potentially infest wetlands throughout much of Australia. It has a wide climate tolerance and has been found in cultivation well outside its predicted range, and has the ability to continue growing even when completely submersed although growth rates are reduced and plants are smaller. It is also very difficult to control because it can spread by both seed and vegetative reproduction, and even tiny pieces of vegetation can give rise to new colonies.


Source: cabi.org
Description

H. brevipes is an erect annual plant up to 1 m high with a square stem typical of the family, often densely hairy but sometimes less so. Leaves are also normally coarsely hairy on both surfaces, opposite, narrowly ovate or lanceolate, 4-7 cm long, up to 2 cm wide, cuneate at the base, the margins irregularly serrate. Apex acute to acuminate. The inflorescence is a dense raceme, almost globose, up to 14 mm diameter, on a peduncle about 1 cm long in the axils of most upper leaves. Corolla white or purplish-white, irregularly five-lobed about 5 mm long. The calyx, 4 mm long, also has 5 narrow, finely barbed lobes. Bracts lanceolate, 8-12 spreading or reflexed, 4-6 mm long, almost concealed by the flowers. Seeds ovoid, up to 1 mm long, dark brown to black, obscurely striate, with a conspicuous scar.

Impact

H. brevipes is an annual plant of cultivated land and wastelands, including forest edges, wet ground and rice crops, and is favoured by continuous wet conditions, without a prolonged dry season. It is native to Mexico, the Caribbean and much of South America and has been widely introduced across South East Asia, where it has naturalized. H. brevipes may be accidentally introduced into a new area as a contaminant of seed, in particular with rice. It has been listed as a ‘principal’ weed of Malaysia and a common weed of Borneo, Philippines and Taiwan (Holm et al., 1979). In addition, PIER (2017) report that H. brevipes is invasive in Singapore, Thailand and Vietnam. Lorenzi (1982) describes it as a damaging weed of humid conditions along the coast, where it can develop into large infestations. H. brevipes is typically a weed of agricultural land, causing yield losses and a negative economic impact.

Hosts

H. brevipes is primarily a weed of rice, especially in South East Asia, including Malaysia (Yong and Goh, 1977). In Indonesia it is noted to be a weed in rain-fed and upland rice fields, grasslands, rubber, cacao, young oil palm and sugar cane plantations and orchards (Knowledge Management Center on Topical Biology, 2017). It is also listed among weeds in mung bean in Indonesia (Bangun et al., 1986) and in Phaseolus beans in Brazil (Laca-Buendia et al., 1989).


Source: cabi.org
Description

The following description is from Flora of China Editorial Committee (2017)

Hosts

I. carnea subsp. fistulosa is considered a serious weed in cultivated rice fields due to its strong competitive ability (Frey, 1995).

Biological Control
I. carnea subsp. fistulosa seeds are heavily infested by the beetle Megacerus flabelliger, which has been suggested as a biological control agent in areas where this plant is a troublesome weed (e.g. India). However, an uncontrolled release of the beetle could have devastating consequences for the crop Ipomoea batatas and its hundreds of associated economically important varieties (Frey, 1995).

Source: cabi.org
Description

I. rugosum is a vigorous annual (in strongly desiccating soil) or short-lived perennial, tufted, sometimes with stilt roots, rooting at the nodes, with erect, slanting or ascending, often much-branched culms, up to 1.5 m tall. The species can be identified by the distinctive, prominent transverse ribs or ridges on the lower glume of the spikelet. The spinal awns are prominent and the nodes of the culm are tufted and hairy.
The leaf sheaths are usually loose, up to 16 cm long, glabrous or hairy like the blades, with some long, slender, bulbous-based hairs on the margin and at the base at the node (Gilliland et al., 1971). The leaf blades are acuminate, the lower ones narrowed gradually to the base;30 cm long x 1.5 cm wide;the margin is cartilaginous and scabrid, the base densely hairy. The ligule is variable, a brownish membrane, 6 mm deep.
The inflorescence is terminal, apparently simple when young, but separating with age into its two constituent racemes, usually 7-10 cm long;each raceme with the spikelets arranged in pairs, one sessile, one pedicelled, on one side of the triangular, hairy rachis. Sessile spikelet, callus thick, lower glume keeled and membraneous, 5 mm long with distinct transverse ridges (hence 'rugosum;upper glume ovate-acute, keeled 5.2 mm long;lower floret usually male, 4.6 mm long;epper lemma with a twisted awn up to 20 mm long;anthers 3, 2 mm long;grain ovoid, brown, 2 mm long. Pedicelled spikelet on a stout pedicel, 1 mm long;lower glume ovate-acute, 4.4 mm long;upper glume boat-shaped, keeled, acute, 4.1 mm long;lower lemma hyaline, 3-nerved, the margins folded;palea similar, 2-nerved, upper lemma male, 3 mm, hyaline without an awn or with a very small, thin one (Gilliland et al., 1971).

Impact

I. rugosum is a C 4 grass species widely cultivated and naturalized in moist, tropical habitats around the world (Clayton et al., 2015;USDA-ARS, 2015). It is an opportunistic and effective colonizer of open and disturbed areas, swamps, and along roadsides. It is a serious weed in many crops, especially in paddy fields and sugarcane plantations (Holm et al., 1977;Baki and Manidool, 1992). I. rugosum is a highly invasive grass which can produce up to 4,000 seeds per plant and has the potential to grow even in shaded areas (Holm et al., 1977;PROTA, 2015). I. rugosum is listed as invasive in Costa Rica, Cuba, the Dominican Republic and Fiji (Kairo et al., 2003;Chacon and Saborio, 2012;Oviedo Prieto et al., 2012;PIER, 2015). In the USA, the Department of Agriculture considers it a noxious weed;plants found growing within the continental USA should be promptly reported to that agency (Barkworth et al., 2003).

Hosts

I. rugosum is found mainly in rice, but also amongst other crops which are grown under wetland conditions. It is also sometimes found in sugarcane (Holm et al., 1977). It is named by Holm et al. (1977) as a weed of six or more crops in Cuba, Colombia, Malaysia and China, and of between two and five crops in Peru and Guyana.


Source: cabi.org
Description

L. camara is a medium-sized perennial aromatic shrub, 2-5 m tall, with quadrangular stems, sometimes having prickles. The posture may be sub-erect, scrambling, or occasionally clambering (ascending into shrubs or low trees, clinging to points of contact by means of prickles, branches, and leaves). Frequently, multiple stems arise from ground level. The leaves are generally oval or broadly lance-shaped, 2-12 cm in length, and 2-6 cm broad, having a rough surface and a yellow-green to green colour. The flat-topped inflorescence may be yellow, orange, white, pale violet, pink, or red. Flowers are small, multicoloured, in stalked, dense, flat-topped clusters to 4 cm across. Fruit is a round, fleshy, 2 seeded drupe, about 5 mm wide, green turning purple then blue-black (similar in appearance to a blackberry).

Recognition

L. camara is conspicuous due to its attractive and multicoloured floral displays and is a well-known species throughout the tropics.

Impact

L. camara is a highly variable ornamental shrub, native of the neotropics. It has been introduced to most of the tropics and subtropics as a hedge plant and has since been reported as extremely weedy and invasive in many countries. It is generally deleterious to biodiversity and has been reported as an agricultural weed resulting in large economic losses in a number of countries. In addition to this, it increases the risk of fire, is poisonous to livestock and is a host for numerous pests and diseases. L. camara is difficult to control. In Australia, India and South Africa aggressive measures to eradicate L. camara over the last two centuries have been largely unsuccessful, and the invasion trajectory has continued upwards despite control measures. This species has been the target of biological control programmes for over a century, with successful control only being reported in a few instances.

Hosts

L. camara is an agricultural weed that can cause dramatic losses in yields. In Australia, it was reported that L. camara infested 4 million ha of pasture (Parsons and Cuthbertson, 1992). A number of plants affected by L. camara are listed in the "Host Plants/Plants Affected" table below.


Source: cabi.org
Description


Perennial, loosely tufted to rhizomatous. Culms erect or geniculate and rooting from lower nodes, up to 100 cm or more tall. Leaf sheaths glabrous;leaf blades tough, usually involute, 5-30(-50) × 0.15-0.3(-0.6) cm, adaxial surface scabrid, abaxial surface subglabrous;ligule 3-12 mm, acute. Inflorescence 15-25 cm, scabrid;racemes 3-28, indistinctly unilateral, 4-20 cm, straight, ascending or spreading, spikelets usually distant. Spikelets glaucous-green, subterete, 6-14 mm, florets 5-12;glumes keeled;lower glume lanceolate, 2-3 mm, acute;upper glume narrowly oblong, 3-4 mm, acute or mucronate;lemmas narrowly oblong, dorsally sub-rounded, lowest 4-5 mm, lower lateral veins pilose, entire or 2-dentate, midvein often produced into a short 0.3-1.6 mm awn;palea ciliolate along upper keels. Callus laterally pilose. Anthers 0.5-0.75(-2.5) mm. Caryopsis elliptic-oblong, 1.5-2.5 mm, dorso-ventrally flattened. Flowers from June to September (based on description of L. fusca ssp. fusca from Flora of China, 2014).

Impact

L. fusca is a perennial weed with a global distribution. It is an aggressive species showing a competitive advantage in many situations due to its tolerance of saline and alkaline soils and its likely ability to fix nitrogen. It is commonly a serious weed of rice in many countries, and is of particular concern in Spanish rice fields. It is recorded as invasive on Hawaii and in the Chagos Archipeligo (as L. fusca ssp. uninervia) (PIER, 2014) and has been the subject of an ‘eradication action’ in Europe (Brunel et al., 2013).

Hosts

L. fusca (mainly ssp. fasciculari) is a major weed of rice in a number of countries including USA, Cuba and Spain. L. fusca ssp. fusca is also problematic in rice in India and other countries. It can also occur in lucerne/alfalfa, tomatoes and turf.


Source: cabi.org
Description

L. peploides is an emergent and floating herbaceous perennial macrophyte. It has glabrous or pubescent stems 1-30 dm that can creep horizontally as well as grow vertically. Early growth resembles a rosette of rounded leaves growing on the water’s surface. Alternate leaves are polymorphic and less than 10 cm long and oblong to round, often lanceolate at flowering. The species exhibits root dimorphism and has adventitious roots that form at nodes and ensure oxygen uptake. Flowers are 5-merous (pentamerous), grow from leaf axils, are bright yellow, and can be from 7 to 24 mm long. Fruit is in a five-angled reflexed capsule, about 3 cm long that contains 40-50 seeds 1.0-1.5 mm long, embedded in the inner fruit wall (EPPO, 2004;The Jepson Online Interchange, 2009).

Impact

L. peploides is a productive emergent aquatic perennial native to South and Central America, parts of the USA, and likely Australia (USDA-ARS, 1997). It was introduced in France in 1830 and has become one of the most damaging invasive plants in that country (Dandelot et al., 2008). It is often sold as an ornamental, which likely explains its introduction to Europe. It has been more recently introduced to areas beyond its native range in the USA, where it is often considered a noxious weed (INVADERS, 2009;Peconic Estuary Program, 2009). L. peploides is adaptable, and tolerates a wide variety of habitats where it can transform ecosystems both physically and chemically. It sometimes grows in nearly impenetrable mats;it can displace native flora and interfere with flood control and drainage systems, clog waterways and impact navigation and recreation (Peconic Estuary Program, 2009). The plant also has allelopathic activity that can lead to dissolved oxygen crashes, the accumulation of sulphide and phosphate, ‘dystrophic crises’ and intoxicated ecosystems (Dandelot et al., 2005).

Hosts

Impacts on the local environment by L. peploides can be devastating. The species possesses an allelopathic activity that has year-long effects on water quality and can lead to impoverished flora by decreasing seedling survival of vulnerable native taxa (Dandelot et al., 2008). L. peploides can also cause severe hypoxia and sometimes anoxia during the summer. It can also lead to reduced sulphate and nitrate levels and increased sulphide and phosphate concentrations. These combined effects have the capability of fomenting what Dandelot et al. (2005) refer to as “a dystrophic crisis” and an intoxicated ecosystem. The plant has been reported to outcompete native Myriophyllum and Potamogeton species in France, which translates to a reduction in macroinvertebrate habitat (Dutartre, 1986;CEH, 2007). It also supplants native wetland grasses, some of which are used as forage for livestock (CEH, 2007).


Source: cabi.org
Description


Herbs 10-20 cm tall, annual or perennial, creeping, sprawling, prostrate, or decumbent. Stems villous, often rooting at nodes. Petioles 0.2-3 (-4) cm, villous;leaf blade elliptic to ovate, 1-2 × 0.4-1.2 cm but basal ones sometimes 6-12 × 3.5-5 cm, both surfaces villous, base cuneate, margin entire, apex acute. Spikes 1.5-4 cm long;bracts elliptic, overlapping, 6-7.5 × 3-4 mm, 5-7 veined. Calyx abaxial lobe approximately 2 × 0.6 mm, apex 2-lobed;adaxial lobe approximately 3 × 1 mm;lateral lobes approximately 2 × 0.5 mm. Corolla bluish purple or white, externally glabrous;tube cylindric for approximately 1.5 mm, contracted near midpoint then expanded into throat;lower lip approximately 2.3 mm;upper lip approximately 2 mm. Stamens inserted at base of throat;filaments 0.5 mm, glabrous. Ovary glabrous with 4-8 ovules per locule. Fruit a capsule of approximately 5 × 2 mm, 8 to 16 seeds. Seeds broadly ellipsoid and granulate (Flora of China Editorial Committee, 2014).

Hosts

N. canescens has been recorded growing as a weed in rice, maize, melon, and oil palm plantations (Ekeleme and Chikoye, 2003;Essandoh et al., 2011;Mahbubur, 2013).


Source: cabi.org
Description

The following description is taken from Flora of North America Editorial Committee (2016)

Impact

N. lotus is a floating leafed macrophte and water lily, native to Africa and specific areas in Europe. It has a number of medicinal properties and is often introduced into new areas as an ornamental. This species has become naturalized in North America and some countries in South America and Asia, but no published reports of it being invasive were found other than presence (without further details) on an invasive species list for Louisiana (Louisiana Department of Wildlife and Fisheries, 2015). There are limited reports of the impact of this species, although in newly reclaimed wetlands in the Nile Delta, Egypt, N. lotus has been observed colonizing rice fields causing a significant decrease in growth and yield. Khedr and Hegazy (1998) describe it here as having "rampant behaviour as an aquatic weed invading the newly reclaimed ricefields," with its aggressiveness related to being able to spread through both vegetative and sexual reproduction.

Hosts

N. lotus is recorded as a weed in rice fields in Egypt where it can significantly reduce the growth and grain yield of the crop (Khedr and Hegazy, 1998;Hegazy et al., 2001).


Source: cabi.org
Description

The following description is from Flora of China Editorial Committee (2017)

Impact

Paspalum dilatatum is a perennial grass native to South America that has been introduced into tropical and subtropical areas as a forage species/fodder. It is reported as invasive in Japan, Malaysia, Taiwan, Vietnam, Indonesia, Philippines, Hawaii, American Samoa, Australia, Fiji, French Polynesia, New Caledonia, New Zealand, Niue, Norfolk Island, Solomon Islands and the Minor Outlying Islands. In Hawaii and New Zealand, it forms dense stands that smother and prevent recruitment of native species.

Hosts

P. dilatatum is reported as a weed of cultivation and is sometimes present in rice fields (Heuzé et al., 2015;Flora of China Editorial Committee, 2017). When the species is infected by the ergot fungus, Claviceps paspali, it becomes toxic to animals that feed on it (FAO, 2017;PROTA, 2017;USDA-ARS, 2017).


Source: cabi.org
Description


Grass species are notoriously difficult to identify. P. urvillei is a perennial grass that grows in clumps or tufts of a few to many stems growing from a short rootstock. The stems are purplish and hairy at the base but green and smooth towards the top;they are from 0.75 to 2.5 metres tall. The blades are green, vase-shaped, bristly and firm, 12 to 48 cm long (commonly 20 to 30 cm) and 3 to 15 mm wide;rarely, they can be up to 65 cm long and 2 cm wide. The inflorescences are 10-20 cm long, borne on a central axis 4-13 cm long. Each flower cluster bears six to 25 spikes. Four to thirty seedheads, grouped on spreading branches, have paired seeds lined up in 4 rows. Seeds are brown when mature and fringed with fine hairs, and may feel sticky. They characteristically lie on one side of the branch.

Impact

Paspalum urvillei is a well-known weed of agricultural fields and disturbed areas (Randall, 2012), but it has been widely introduced as a forage grass to ecosystems outside South America (Hitchcock, 1936;PIER, 2012;Bowen & Hollinger, 2002). It is now widely naturalized and is able to invade grasslands, shrublands and wetlands. It invades and establishes in highly disturbed natural ecosystems where it grows in dense stands, displacing indigenous vegetation and altering the lower strata (Western Australian Herbarium, 2012). It is listed as invasive in Portugal, Réunion, and the United States (NIISS, 2012;USDA-NRCS, 2012).

Hosts

P. urvillei often acts as an invasive agricultural weed (Randall, 2012). It is also a host of the rice stink bug Oebalus pugnax (Naresh and Smith, 1984), the Mexican rice borer Eoreuma loftini (Bezeulin et al, 2011), and the crop pathogenic bacterium Acidovorax avenae (Saddler, 1984);and it shows allelopathic activity (exudates) that can impact crop systems (Ishimine et al., 1987). Crops affected in one or more ways include rice Oryza sativa (Naresh and Smith, 1984;Bezeulin et al, 2011), sugarcane Saccharum (Bezeulin et al, 2011), maize (Zea mays), the fodder grass Hemarthria altissima (Newman and Sollenberger, 2005), Strelitzia nicolai, Sorghum spp., oats (Avena), millet, pineapples (González-Ibáñez, 1987), apples (Losso and Ducroquet, 1983) and citrus (Phillips & Tucker, 1974). P. urvillei is also an invasive weed of disturbed sites, footpaths, parks, gardens, turf, roadsides, waste areas, wetlands, watercourses (i.e. riparian habitats), open woodlands, closed forests and pastures as well as affecting the abovementioned crops (Queensland Government, 2012;Randall, 2012;Askew, 2012;Weakley, 2011;Quattrocchi, 2006;Motooka et al., 2003).


Source: cabi.org
Description

R. ellipticus is a stout, weakly climbing, evergreen shrub 1–3 m tall. Branchlets purplish brown or brownish, pubescent, with sparse, curved prickles and dense, purplish brown bristles or glandular hairs. Leaves imparipinnate, 3-foliolate;petiole 2–6 cm, petiolule of terminal leaflet 2–3 cm, lateral leaflets subsessile, petiolule and rachis purplish red bristly, pubescent, with minute prickles;stipules linear, 7–11 mm, pubescent, with intermixed glandular hairs;blade of leaflets elliptic or obovate, 4–8(–12) × 3–6(–9) cm, terminal leaflet much larger than lateral leaflets, abaxially densely tomentose, with purplish red bristles along prominent veins, adaxially veins impressed, pubescent along midvein, base rounded, margin unevenly minute sharply serrate, apex acute, abruptly pointed, shallowly cordate, or subtruncate. Inflorescences terminal, dense glomerate racemes, (1.5–)2–4 cm, flowers several to 10 or more, or flowers several in clusters in leaf axils, rarely flowers solitary;rachis and pedicels pubescent, bristly;bracts linear, 5–9 mm, pubescent. Pedicel 4–6 mm. Flowers 1–1.5 cm in diameter. Calyx abaxially pubescent, intermixed yellowish tomentose, sparsely bristly;sepals erect, ovate, 4–5(–6) × 2–3(–4) mm, abaxially densely yellowish gray tomentose, apex acute and abruptly pointed. Petals white or pink, spatulate, longer than sepals, margin premorse, densely pubescent, base clawed. Stamens numerous, shorter than petals;filaments broadened and flattened basally. Ovary pubescent;styles glabrous, slightly longer than stamens. Aggregate fruit golden yellow, subglobose, approximately 1 cm in diameter, glabrous or drupelets pubescent at apex;pyrenes triangular-ovoid, densely rugulose (Wagner et al., 1999;Flora of China Editorial Committee, 2015).

Impact


The invasiveness of the thorny shrub R. ellipticus has been most thoroughly documented on the island of Hawaii. Since the first report of its escape from cultivation in 1961, this species has become established in mid-elevation forest and pastureland, forming tall, dense thickets. Seeds are sufficiently viable following passage through the digestive systems of birds and mammals to readily germinate in pastureland and undisturbed forest sites where they are deposited. Several introduced frugivorous birds and feral mammals, are capable of dissemination of seeds via ingestion of the succulent fruit and birds in particular, are able to carry seeds to adjacent sites. It can also spread by suckers and resprouts vigorously after fire. The ability to colonize undisturbed native forests and displace native species is cause for alarm among resource managers of Hawaii Volcanoes National Park and other natural reserves of Hawaii, comprised of highly ecologically sensitive systems. It has been listed as one of the world’s 100 worst invasive alien species (Lower et al., 2000), and is a prohibited species in South Africa (NEMBA Category 1a).

Hosts

R. ellipticus encroaches upon rice fields in China and elsewhere in Asia if farmers do not manually control this bramble. R. ellipticus invades apple, and other temperate fruit orchards in India (Misra and Sharma, 1970;Misra and Singh, 1972). Its weedy habit is particularly evident in Hawaii where it aggressively colonizes cleared pastureland and encroaches into native forests, forming tall, dense thickets.


Source: cabi.org
Description

S. indica is a tufted mostly glabrous annual that can grow to 0.6 m high.

Recognition


As the only cosmopolitan species within the genus, S. indica is best described by length of its spikelet, the length if its upper glume, the length of the inferior lemma, the length of its anther upper flower, its hyaline ligules and its having an apex acute upper glume (Gennaro and Scataglini, 2012). Simon (1972) wrote that it is ‘characterized by a spikelet containing two florets of which the lower is male or barren, and the upper hermaphrodite. It is delimited from the type genus Panicum by the strongly saccate nature of the base of the upper glume and to a lesser extent of the lower lemma, and by the inflorescence... being a false spike (morphologically a much contracted panicle)’ (Simon, 1972). S. indica can also be distinguished from the rest of Paniceae by the presence of spiciform panicle with ribbed glumes and gibbous upper glumes (Teerawatananon et al., 2011).
S. indica is very similar to other Sacciolepis species such as S. spiciform (Flora Zambesiaca, 1989). Flora Zambesiaca conserves that S. indica ‘ can usually be distinguished by spikelet length and habit, but absence of leaf papillae is the most reliable character though it requires use of a microscope.’ Spikelet length and smooth pedicels can be used to quickly distinguish S. indica from S. myosuroides (Simon and Alfonso, 2012).
African specimens of S. indica often have little auricles. These specimens have been described as S. auriculata in the past. However, according to Flora Zambesiaca (1989), S. indica intergrades completely from forms with auricles to the commoner form that lacks auricles (Scholz, 1980;Flora Zambesiaca, 1989).

Impact

S. indica is an annual C3 grass (Aliscioni et al., 2003;De Gennaro, 2011). It is highly variable in size, spikelet length and pubescence, and it flowers sporadically throughout the year (Simon and Alfonso, 2012). S. indica is found in tropical and subtropical rainforests, tropical and subtropical sub-humid woodlands, and coastal grasslands.


Source: cabi.org
Description

S. verticillata is an annual, or more usually perennial. Stems straggling, to 100 cm or more, glabrous or nearly so, usually erect and simple or sparsely branched, often copiously branched from the base, usually 40 cm high or less, the stems tetragonous. Stipule sheath very short, the setae about 1.5 mm long;leaves glabrous, sessile or nearly so, linear or lanceo-linear, mostly 1.5-4 cm long and 1.5-6 mm broad, commonly 1-veined, often with fascicles of smaller leaves in the axils. Flowers white, very small in sessile clusters at the upper stem nodes or more usually terminal, then the heads subtended by 2 or 4 leaf-like bracts. Hypanthium pilose above, the 2 sepals narrowly triangular, 1.5 mm long or less. Corolla of 4 petals, 3 mm long, hispidulous outside at the apex, the lobes about equalling the tube;anthers exserted. Capsule 2.5 mm long;seeds reddish brown about 1 mm long (PIER, 2016).

Impact

S. verticillata is a scrambling annual or perennial native to the Americas. It has been introduced widely but sporadically across Asia and the Pacific and to tropical Australia. It can grow on a wide range of land types but often requires disturbance to establish. S. verticillata can form large clumps which can smother other vegetation. In its native range it has been recorded as a significant weed of agricultural crops, for example in the Caribbean it is a problem of sugarcane, vegetables and root crops (Fournet and Hammerton, 1991). In addition to this, on St Helena, it is among the exotic plants threatening the critically endangered fern, Pteris adscensionis.

Hosts


In a number of countries S. verticillata has been shown to have a negative impact on agricultural crops such as Coffea arabica, Oryza sativa, Phaseolus vulgaris, Saccharum officinarum, Theobroma cacao, Vigna unguiculata Manihot esculenta and Zea mays (Fournet and Hammerton, 1991;Holm, 1997;Johnson, 1997;Marques et al., 2011;Cherigo et al., 2012).


Source: cabi.org
Description

Annual grass. Culms slender, creeping, rooting at lower nodes, ascending to 10-50 cm tall. Leaf sheaths glabrous, one margin densely ciliate;leaf blades lanceolate, 2-6 × 0.3-1.2 cm, glabrous or loosely hispidulous, base subcordate, margins scabrous, pectinate-ciliate at base;ligule c. 1 mm, ciliate. Inflorescence pyramidal, axis 1-8 cm;racemes 3-6(-12), 0.5-4 cm, spreading;rachis triquetrous, scabrous;spikelets paired, crowded, pedicels setose. Spikelets ovate or ovate-elliptic, 2-2.5 mm, usually glabrous, acute;lower glume cufflike, 1/8-1/4 spikelet length, thinly membranous, veinless or obscurely 3-veined, truncate or rounded;upper glume (5-)7-9-veined;lower lemma 5-veined, palea well developed;upper lemma broadly elliptic, 1.8-2 mm, finely rugose, apiculate (Flora of China Editorial Committee, 2018).

Impact

Urochloa reptans is an annual grass regarded as native to Asia, the Arabian Peninsula, Australia and the Pacific region, although its status is ambiguous in many countries. The species grows forming clumps of slender, creeping culms up to 50 cm tall that are capable of displacing other plants and grasses. It is considered an important weed in agricultural lands and pastures, but it can also invade disturbed sites, degraded forests, coastal areas, river and creek beds, and riparian forests. Currently, it is listed as invasive in Costa Rica, Puerto Rico, the United States Virgin Islands and some islands in Oceania, where it has been reported invading relatively undisturbed forests.

Hosts

U. reptans is considered a weed of soybean, cotton, maize, rice, sugarcane fields and active pastures (including heavily-grazed pastures). It also grows as a weed of gardens and lawns (Tiwari and Kurchania, 1990;Auld and Kim, 1996;Gupta, 2013;PIER, 2018).


Source: cabi.org
Description

C. aspersum is a large-sized land snail, with a shell generally globular but sometimes more conical (higher spired) and rather thin in the common form when compared to other Helicinae. The umbilicus is usually completely closed by a thickened white reflected lip that defines the peristome in adult snails. The shell is sculptured with fine wrinkles and rather coarse and regular growth-ridges and is moderately glossy because of a fine periostracum. The peristome is roundly lunate to ovate-lunate. Adult shells (4½ to 5 slightly convex whorls) measure 28-45 mm in diameter, 25-35 mm in height (Kerney and Cameron, 1979). The shell ground colour is from yellowish to pale brown. The shell also shows from zero to five reddish brown to blackish spiral bands superimposed on the ground colour and usually interrupted such that the ground colour appears as yellow flecks or streaks breaking up the bands;the bands are occasionally separated by a median white spiral line (fascia albata). Fusion of two or more adjacent bands and diffusion of band pigment on the whole shell surface are often observed. Frequently, the upper half of the shell is darker because of the effect of a dominant factor (Albuquerque de Matos, 1985). The banding pattern is much less distinct and more broken than that exhibited by the well-known polymorphic snails Cepaea nemoralis and Cepaea hortensis.

Recognition


The following information is from the Canadian Food Inspection Agency Cornu aspersum fact sheet (CFIA, 2014).
Indications of an attack by C. aspersum are ragged holes chewed in leaves, with large veins usually remaining;holes in fruit;and slime trails and excrement on plant material.
Adults and larger juveniles are likely to be visible among the host material or attached to the transporting containers. They may also be hidden in protected locations, sealed into their shells to avoid desiccation. Check the undersides of containers and their rims. Small snails and eggs in soil could be difficult to find. C. aspersum hides in crevices and will overwinter in stony ground.
Inspections are best carried out under wet, warm and dark conditions. Under bright, dry conditions it is necessary to thoroughly search dark, sheltered areas where the humidity is elevated, such as under low-growing plants or debris. The snails may bury themselves in loose soil or other matter, so the only way to be reasonably sure an area is not infested is to make repeated surveys over a long period of time.

Symptons

C. aspersum causes extensive damage in orchards (creating holes in fruit and leaves) and to vegetable crops, garden flowers and cereals.
In California, USA, populations established in citrus groves feed essentially on the foliage of young citrus and also on ripe fruits, creating small holes allowing the entry of fungi and decay of the fruit (see Pictures). Larger holes result in fruit dropping from the tree or being rejected for consumption during sorting and packing (Reuther et al., 1989;Sakovich, 2002).
In South African viticultural regions, C. aspersum feeds essentially on the developing foliar buds and young leaves of the vines. In kiwifruit vineyards (California, New Zealand), damage occurs on the flowers, not the fully developed fruit, since snails consume only the sepal tissue around the receptacle area. Damage to the sepals can be detrimental by increasing the development of the fungus Botrytis cinerea during cold storage of fruits, and moreover, the slime trail mucus stimulates germination of B. cinerea conidia (Michailides and Elmer, 2000).

Impact

C. aspersum, the common garden snail, is represented by several forms that are highly differentiated genetically. Only one lineage, the western one, is considered to be invasive in regions where it has been introduced recently (since the sixteenth century) either accidentally or intentionally (e.g. North and South America, South Africa, Oceania). It was in California, USA, where it was introduced in the 1850s, that it was first treated (1931) as a regulated pest. Its success in colonizing new areas after introduction and establishment may be due to: (i) large phenotypic variation in combinations of life-history traits, especially reflecting a high degree of plasticity (e.g. trade-off of egg weight/egg number), and (ii) great resistance against natural enemies. Also, genetic data indicate that C. aspersum is capable of establishing even after a severe genetic bottleneck.

Hosts

C. aspersum is a polyphagous grazer with a large diet spectrum. In its natural habitat, it feeds on wild plants such as Urtica dioica or Hedera helix, which are also used for shelter. In human-disturbed habitats, a wide range of crops and ornamental plants are reported as hosts: these include vegetables, cereals, flowers and shrubs (Godan, 1983;Dekle and Fasulo, 2001). In particular, it causes serious damage in citrus groves and vineyards. It will feed on both living and dead or senescent plant material. The Host Plants/Plants Affected table does not cover all plants that C. aspersum will feed on, as the list is so extensive but aims to provide an insight to the well-known species affected. The categorization as 'Main', 'Other' or 'Wild host' is also subjective and should not be considered definitive.

Biological Control
<br>As terrestrial molluscs have many natural enemies, there has been strong interest in the biological control of C. aspersum using other, predatory snails (e.g. Fisher and Orth, 1985). However, as most of these predatory snails are not host-specific, they are not appropriate to use in control programmes in which effects on non-target species are of concern (Cowie, 2001: Barker and Watts, 2002).<br>There have been several attempts to develop biological control of C. aspersum in California, South Africa and New Zealand, which began with the introduction of predaceous snails (Euglandina rosea, Gonaxis sp.) and beetles during the 1950s and early 1960s (for more information see Fisher and Orth, 1985;Barker and Efford, 2004). These efforts were largely unsuccessful, although one staphylinid beetle (Staphylinus (Ocypus) olens) showed potential;however, the use of this species as a biological control in orchards has not been actively pursued (Sakovich, 2002). In 1966, however, another (opportunistic) predaceous snail, the decollate snail Rumina decollata (of European origin) was found to have invaded California (see Pictures). Experimental releases of R. decollata in southern California citrus orchards were begun in 1975 and, in most cases, resulted in complete control (displacement) of C. aspersum (Fisher and Orth, 1985). Rumina decollata is now used to control C. aspersum in some 20,000 ha of citrus in southern California, but is currently permitted only in certain Californian counties (Dreistadt et al., 2004). As this predatory snail consumes young to half-grown snails, control is achieved only in 4-6 years. Sakovich (2002) recommended first using molluscicidal baits to reduce the population, and then combining skirt-pruning and copper barriers with introduction of R. decollata. Once control by R. decollata is achieved, maintenance of copper barriers can cease, R. decollata can be harvested and transferred to new areas. However, Cowie (2001) expressed concern regarding both the effectiveness of R. decollata in control of C. aspersum, its potential impacts on native (even endangered) species and its potential as a garden plant pest.<br>A study by Altieri et al. (1982) was carried out in a daisy field in northern California to determine the effectiveness of the indigenous coleopterous predator Scaphinotus striatopunctatus in the biological control of C. aspersum. Release of the predator in the field under light metal sheets, together with colonization by garter snakes (Thamnophis elegans) from an adjacent field, resulted in a significant reduction in snail populations.<br>In South Africa, the native predacious gastropod Natalina cafra was investigated as a potential biological control agent against C. aspersum, with special attention to the possibility of establishing a viable population of the natural enemy in captivity (Joubert, 1993), but this approach seems not to have been implemented.<br>Research by the Entomology Division of the Plant Protection Department, Cukurova University, Turkey, on the importation of predators and parasitoids as biological control agents (mainly for citrus pests) included the coccinellid Hippodamia convergens as a potential predator of C. aspersum (Uygun and Sekeroglu, 1987).<br>Ducks, chickens or guinea fowl can provide long-term control in citrus orchards and vineyards, if an appropriate breed is chosen and properly cared for. Growers take the animals each morning into the orchard for as little as half an hour to scavenge for food. This solution can be very effective but involves extra labour in managing the animals and protecting them from predators (Sakovich, 2002;Davis et al., 2004).

Source: cabi.org
Description

The following description is from the Flora of China Editorial Committee (2016)

Impact

Erechtites hieraciifolius is a fast-growing, annual herb that is native to North, Central and South America and the Caribbean. It is recorded as an environmental and agricultural weed in areas both within and outside its native distribution. Mature plants can produce large amounts of wind-dispersed seed, facilitating the colonisation of new areas. It is adapted to grow in a wide range of disturbed anthropogenic habitats and can outcompete other species to form dense populations. It may also spread as a seed contaminant of crops. Currently, it is listed as invasive in Hong Kong, Hawaii, the Galapagos Islands, French Polynesia, Palau, US Minor Outlying Islands, New Zealand and Hungary. It is also considered a potential weed in Australia, where it is under quarantine.

Hosts

E. hieraciifolius has been listed as a weed of the following crops: oat (Avena sativa), barley (Hordeum vulgare), maize (Zea mays), strawberry (Fragaria ananassa), onion (Allium cepa), carrot (Daucus carota), cranberry (Vaccinium macrocarpon), blueberry (Vaccinium spp.) and sugarcane (Saccharum officinarum);it is also a weed of fodder crops (e.g. Medicago sativa) and of mixed pastures (Darbyshire et al., 2012).


Source: cabi.org
Description

G. quadriradiata is an annual herb, 8–62 cm tall. Leaf blades 20–60 × 15–45 mm. Peduncles 5–20 mm. Involucres hemispheric to campanulate, 3–6 mm diameter. Phyllaries deciduous, outer paleae deciduous, broadly elliptic to obovate, 2–3 mm;inner deciduous, linear to lanceolate, 2–3 mm, entire or 2- or 3-lobed, lobes to 1/3 total lengths, blunt. Ray florets (4 or) 5 (to 8);corollas usually white, sometimes pink, laminae 0.9–2.5 × 0.9–2 mm. Disk florets 15–35. Ray achenes 1.5–2 mm;pappus of 6–15 fimbriate scales 0.5–1 mm;pappus absent or of usually 14–20, rarely 1–5, white, lanceolate to oblanceolate, fimbriate, sometimes aristate, scales 0.2–1.7 mm (Flora of North America Editorial Committee, 2014).

Impact

G. quadriradiata is a fast-growing annual herb with the capacity to invade agricultural and other disturbed areas in most temperate and subtropical regions of the world (Kagima 2000;Vibrans, 2009;Kabuce and Priede, 2010;Madsen and Wersal, 2014). It is highly competitive and can spread quickly, often being the dominant species in a field. It is causing considerable economic impact in cropping systems, greenhouses, gardens and nurseries (Madsen and Wersal, 2014). In Europe, this species is recognized as a significant problem for many growers and farmers, including in commercial greenhouses, and its presence may reduce yields up to 10-50% in fields planted with vegetables and crops (Kabuce and Priede, 2010;Madsen and Wersal, 2014).

Hosts

G. quadriradiata is considered to be a common weed in several crops of major importance, such as wheat, maize, coffee, cotton, tobacco, sugarbeet, tomato, pepper, potato, beans, onions, cabbages, garlic, citrus, banana, apple, and strawberry. It is also a common weed in gardens, greenhouses, and nurseries (Damalas, 2008;Vibrans, 2009;Kabuce and Priede, 2010;Madsen and Wersal, 2014).


Source: cabi.org
Description


The live adult female is 2.9-5.0 mm long and 2.4-4.0 mm wide, with a pale yellow oval body covered in white wax or sulfur-yellow flocculent wax tinged with white. In the slide-mounted adult female, the antennae each have 9-11 segments and there are three pairs of abdominal spiracles towards the apex of the abdomen. The center of the abdominal venter becomes invaginated to form a marsupium into which the vulva opens, and there is a marsupial band of simple multilocular pores along the lip of the marsupium, which becomes sclerotized with age.

Recognition


Foliage and stems should be inspected for lumps of white or yellow wax secreted by scale insects, symptoms of pest attack, attendent ants, sticky honeydew and sooty mould growth on leaves. A user-friendly, online tool has been produced for use at US ports-of-entry to help with the identification of potentially invasive scale insect species (Miller et al., 2014a,b).

Symptons


Most damage to plants is caused by the early immature stages of I. samarai, which feed on the leaf undersides, settling in rows along the midrib and veins, and on smaller twigs. The older nymphs feed on larger twigs, and as adults they settle on larger branches and the trunk. Damage to plants results from phloem sap depletion during feeding, leading to shoots drying up and dying. Trees that are badly attacked suffer partial defoliation and a general loss of vigour. The insects dischargesugary honeydew, which can be copious in large colonies and may foul plant surfaces. Besides direct damage by feeding, indirect damage can result from the development of black sooty mould on the honeydew on leaf surfaces, blocking light and air from the plant, leading to a reduction in photosynthesis (Beardsley, 1955).

Impact


The scale insect Icerya samaraia (formerly Steatococcus samaraius) occurs in the Australasian, Oriental and Oceanic zoogeographic regions. It has a wide host range which includes mostly woody plant species in 40 genera belonging to 25 families. It is a minor pest of citrus, banana, coconut, guava, papaya, cocoa, pigeon pea and other plants, including forest and ornamental trees. Populations of I. samaraia are apparently being kept under control on the Palau Islands in the western Pacific Ocean by natural enemies, particularly by the introduced coccinellid Rodolia pumila. I. samaraia can be transported on infested plant materials because of its small size and habit of feeding in concealed areas, making it a potential threat as an invasive species.

Hosts

I. samaraia has been reported on mostly woody plant species in 40 genera belonging to 25 families from the Australasian and Oriental zoogeographic regions (Miller et al., 2014a).

Biological Control
<br>The coccinellid predator Rodolia pumila is believed to be specific to Icerya species and closely related scale insects, and has been used successfully for the biological control of the related species Icerya aegyptiaca on some islands of Micronesia (Schreiner, 1989;Waterhouse, 1993).<br>Of three species of Rodolia (R. pumila, R. cardinalis and R. breviuscula) introduced to the oceanic Pacific for the control of I. aegyptiaca, I. purchasi and I. seychellarum, only R. pumila became widely established on the high islands of Micronesia by the 1950s. R. pumila appears to have been less successful on low coral atolls, possibly after reducing the abundance of its hosts to such low levels that the coccinellid was unsustainable (Beardsley, 1955;Schreiner, 1989;Waterhouse, 1993). This leads to a boom and bust cycle, with predatory beetles disappearing for long enough in some locations for damaging populations of I. aegyptiaca to develop for several years at a time (Waterhouse, 1993). R. pumila is also reported to keep populations of I. samaraia under control in Palau (Beardsley, 1966).<br>Another coccinellid, Cryptolaemus montrouzieri, was introduced for the control of Icerya spp. in Palau and Saipan (Northern Mariana Islands) and became established by 1940 (Schreiner, 1989;Waterhouse, 1993). It has been recorded attacking I. samaraia in Palau (Beardsley, 1955).

Source: cabi.org
Description

P. paniculatum is a perennial grass;culms densely tufted, 0.3 to more than 2 m high, coarse, leafy, erect or ascending, sometimes decumbent at the base and rooting at the lower nodes, finally branching, the nodes glabrous to conspicuously bearded with stiff ascending hairs;sheaths mostly longer than the internodes, keeled, sometimes only on the collar and along the margins, colored orange-brown on the inner surface;ligule 1-3 mm long;blades 9-50 cm long, 6-25 mm wide, usually rounded at the base, densely hispid on both surfaces to nearly glabrous, with a tuft of long hairs on each side at the base, the margins scabrous;inflorescence 5-30 cm long, composed of 7-60 approximate, solitary or somewhat fascicled racemes, the lower ones 4-12 cm long, ascending or arcuate- spreading;spikelets paired, 1.3-1.5 mm long, densely crowded, the glume and sterile lemma equal, barely covering the fruit, softly pubescent, the sterile lemma woolly pubescent only on the margins;fruit about as large as the spikelet, smooth and shining (Flora of Panama, 2016).

Impact

P. paniculatum is a fast-growing grass sometimes used as an “auxiliary forage” crop (PROTA, 2016). Within and outside its native distribution, P. paniculatum behaves as an environmental and agricultural weed and can be found growing along roadsides, in disturbed places, moist shrublands, low open grounds, brushy slopes, forests, open ground, croplands and pastures (Zuloaga et al., 2003;Más and Garcia-Molinari, 2006;Más and Lugo, 2013;AusGrass2, 2016). Plants produce numerous seeds with germination rates higher than 85% (range: 86.5 to 99%, PROTA, 2016). Currently, this species is listed as invasive on Hawaii, Cuba, Trinidad and Tobago, Samoa, Northern Marianas Islands, Micronesia, Fiji, French Polynesia, New Caledonia, Niue, Palau and the Solomon Islands (Wagner et al., 1999;Oviedo Prieto et al., 2012;PIER, 2016;Trinidad and Tobago Biodiversity, 2016).


Source: cabi.org
Description

Mycelium initially hyaline, becoming olive-buff to deep olive-buff, branched, septate, 2-7 µm wide. Conidiophores similar to mycelium in colour, septate, unbranched or occasionally branched, erect, broader towards the distal end, on the host single or fasciculate, emerging through stomata, amphigenous, geniculate or straight, length variable, between septa 17-28 x 3-6 µm. Conidia acrogenous, borne singly or in chains of 2-4, smooth, irregularly ovoid, both ends rounded, or ellipsoid, or conical-ellipsoid, gradually tapering into a beak;beak (a secondary conidiophore) concolorous with the main conidial body, straight, 20-37 x 3-7 µm. Spore body pale-brown to dark olive-buff, becoming darker with age, verrucose, transverse septa 1-10, longitudinal septa 0-5, constricted at septa, varying in size;length including beak 15-89 µm, width 7-30 µm (for additional details, see Prasada and Prabhu, 1962;Prabhu and Prasada, 1970;Anahosur, 1978;Simmons, 1994;2007;Dugan and Peever, 2002).

Recognition

The disease can be detected in the field on the basis of symptoms on the leaf, leaf sheath, awns and glumes. Lesions will lack the dark pycnidia or perithecia produced by some other leaf-spotting fungi (Wiese, 1987). Under severe conditions the heavily infected fields present a distinct burnt appearance that can be seen from a distance (Prabhu and Prasada, 1966).
The agar plate method is recommended for detection in seed (Mathur and Kongsdal, 2003).

Symptons

The disease appears when wheat plants are 7-8 weeks old and becomes severe when the crop is mature. Infection is first evident as small, oval, discoloured lesions, irregularly scattered on the leaves. As the lesions enlarge they become dark-brown to grey and irregular in shape. Some are surrounded by a bright-yellow marginal zone. The lesions vary in size, reaching a diameter of 1 cm or more.
As the disease progresses, several lesions coalesce to cover large areas, resulting in the death of the entire leaf. In some cases the leaf starts drying up from the tip, prematurely, when lesions appear. Black powdery conidia may cover the lesions at this stage under moist conditions. The lowermost leaves are the first to show the signs of infection;the fungus gradually spreads to the upper leaves. In severe cases, similar symptoms are produced on the leaf sheath and stem, as well as the awns and glumes if spikes are infected at the pre-anthesis stage. If the spike is infected this early, seeds do not form. Infection at the dough stage of seed development results in glume infection, ear infection and seed infection. Heavily infected fields present a burnt appearance and can be identified from a distance (Prasada and Prabhu, 1962;Prabhu and Prasada, 1966;Singh, 1990).

Impact

A. triticina is one of several species in the genus that have been isolated from wheat leaves;it is demonstrated to be pathogenic, whereas others appear to be primarily saprophytes. The leaf blight disease it causes has been a serious problem on susceptible cultivars of durum [ Triticum turgidum subsp. durum ] and bread wheat [ Triticum aestivum ] in India. The species has been reported from other hosts and other countries on several continents, but recent taxonomic examinations (Mercado Vergnes et al., 2006;Simmons, 2007) have only supported its presence in southern and southwestern Asia. Nevertheless, it is definitely seedborne, so that the possibility of accidental introduction by that means is a threat for growers using imported seed.

Hosts

The main hosts of A. triticina are bread wheat (Triticum aestivum) and durum wheat (Triticum turgidum subsp. durum). Durum wheats are more severely attacked by the pathogen than are bread wheats (Prasada and Prabhu 1962;Prabhu and Prasada, 1966;Singh et al., 1990). Nevertheless, the results of inoculations by Vergnes et al. (2006) lead them to consider that this fungus is a weak pathogen of wheat with little virulence on modern wheat cultivars.
The pathogen has also been reported to infect Triticum dicoccum (Kulshrestha and Rao, 1976), Triticum sphaerococcum (Kumar et al., 1974a), triticale (Chaudhuri et al., 1976;Wiese, 1987), barley [ Hordeum vulgare ] (Mehiar et al., 1976), oats [ Avena sativa ] (Logrieco et al., 1990) and rye [ Secale cereale ] (Logrieco et al., 1990). Prabhu and Prasada (1966), on the other hand, were not able to obtain infection by inoculation of barley, oats or ten species of wild grasses. Isolation from banana [ Musa paradisiaca ] was reported, although the fungus was probably a secondary invader (Jones, 1991).


Source: cabi.org
Description

A. biennis is an annual or biennial herbaceous plant. Stems are 1–3 m tall (although flowering plants may be as little as a few cm tall), erect and more or less spike-like, simple or somewhat branching at the base from a firm taproot. The stems are glabrous throughout, striate and often reddish.The leaves are alternate, glabrous, sessile, pinnatifid into narrow lobes with the lower leaf segments also pinnatifid, lobes of all but the uppermost toothed. Inflorescence a compound spike-like panicle, leafy throughout, with dense clusters of more or less globose capitula (flower heads) which are nearly sessile along short branches arising from upper leaf axils. Each flower head consists of a hemispheric involucre 2–3 cm long, made of 8–14 glabrous bracts. There are 6–22 or more outer pistillate (ray) florets, and 15–40 central bisexual disc florets. Corollas very small, pale yellow to whitish, with scattered stalked glands;corollas of the outer ray flowers about 1 mm long, somewhat tubular;those of the disk flowers bell-shaped, 1–2 mm long, with five triangular teeth. Cypselae (seeds) obovoid to ellipsoid, glabrous, lacking a pappus (bristles), very small (0.2–0.9 mm long), longitudinally 4-5 nerved and light brown.

Impact


The large seed production, small sticky seeds and adaptation to disturbed habitats facilitated the early and rapid spread of A. biennis beyond its natural range in North America, along transportation corridors and in association with human activities. In recent decades it has become invasive in some agricultural areas in North America. The increasing prevalence of A. biennis in agricultural lands seems to be associated with several factors, including: a shift to annual growth habit;increasing adoption of reduced tillage systems;crop diversification;and, a tolerance to several classes of herbicides. In Europe, the plant has become a local weed, but has not yet been reported as invasive in crops. However, increased frequency has been observed in some countries and changes in land use and agricultural practices suggest the potential for emerging problems in Europe in the future.


Source: cabi.org
Description

F. alnus is a deciduous shrub or small tree usually 4-5 m in height (Tutin et al., 1968), but may grow to 7 m (Gleason, 1963). It develops an erect, slender habit with branches somewhat irregular in alternate pairs, ascending at an acute angle to the main stem (Godwin, 1943). Young twigs are green but turn grey-brown with age and develop red-brown to dark violet tips. Lenticels may be evident as white dots and stripes. Lemon-yellow inner-bark tissues are exposed when the outer-bark is damaged and the young wood is dark brown. Old bark is smooth, except in very old specimens, and readily peels off dead wood. Spines are absent from F. alnus. Leaves are petiolate, obovate in shape, 2-7 cm in length and usually little more than half as wide. They are cuspidate to acuminate in shape, typically ending with a short pointed tip. Leaf margins are entire but wavy, although in seedlings leaves may be serrated. The lower surface of young leaves is pubescent, being covered with dense brownish hairs which are later shed so that older leaves are glabrous and shiny green in colour. Sun leaves are relatively broader and more shiny than shade leaves. The leaves turn yellow, then red in the autumn. Lateral veins are conspicuous on the upper surface of the leaves with 6-12 (commonly 7) pairs running more or less parallel to each other.
F. alnus develops sessile umbels in the leaf axils on young wood with 2-8 flowers borne on stout, unequal, glabrous pedicels 3-10 mm long;occasionally single flowers develop. Individual flowers are greenish-white, about 3 mm in diameter and bisexual. The flowers are 5-merous with broadly obovate petals 1-1.4 mm long and cleft at the tip (Gleason, 1963). Fruits are 6-10 mm in diameter, and change from green to red, then to violet-black on ripening;flowering and fruit development are rather asynchronous, hence all stages of ripening may be present. Each drupe usually contains 2, but occasionally 3, pyrenes or stones which are broadly obovoid in shape, about 5 mm long and 2 mm thick;they have a faint ridge running down the inner face and a deep furrow at the base. Young and Young (1992) report 52 seeds/g for F. alnus. Germination is hypogeal (Godwin, 1943).

Impact

F. alnus was introduced to North America from Europe more than 100 years ago. Once established it maintains itself due to prolific seed production, vigorous growth over an extended growing season and its ability to regenerate following burning and cutting. These characteristics make it difficult to eradicate. Repeated cutting and application of herbicides required to eliminate F. alnus is laborious and expensive. Consequently, most restoration work has been conducted in natural ecosystems of special interest. Its adverse effect on native species arises because F. alnus shades out understorey plants. Its aggressive character, especially in wetlands, is widely noted (Catling and Porebski, 1994).

Hosts

F. alnus is a problem species in native communities because it establishes in dense stands which shade out other understorey species. Possessky et al. (2000) reported a reduction in composition and abundance of the herbaceous cover in riparian habitats in the northern Allegheny Plateau (of Pennsylvania, New York and Ohio, USA) following invasion by F. alnus. Similarly, Reinartz (1997) described how an undisturbed bog community in Wisconsin was invaded by F. alnus in 1955 with a dense tall shrub canopy dominating the site within 12 years. The species is listed as an invasive weed in Tennessee and Wisconsin, USA (Southeast Exotic Pest Plant Council, 1996;Hoffman and Kearns, 1997). F. alnus was recently rated as one of the six principal invasive aliens of wetlands in Canada, and one of four principal invasive aliens in Canadian uplands. In a national survey it was rated second to purple loosestrife (Lythrum salicaria) with respect to the extent to which it is spreading in natural habitats and its severity of impact in Canada (White et al., 1993).
F. alnus is associated with crown rust (Puccinia coronata) which infects several cool season turfgrasses, native grasses and cereals. The uredia, telia and basidiospores are produced on the graminoid hosts, the aecia and pycnia are produced on F. alnus (and Rhamnus cathartica;Partridge, 1998). Alfalfa mosaic virus, which infects a wide variety of plants, including crops, and is vectored by aphids, has also been isolated from young leaves and root cuttings of F. alnus in Italy (Marani and Giunchedi, 2002).


Source: cabi.org
Description

R. repens is a long-lived perennial that forms dense stands by sprouting shoots from its creeping, horizontal roots. Adventitious buds on lateral roots produce erect stems that are thin, openly branched, and 0.5-0.7 m tall. Young stems are covered with woolly hairs, which rub off in time, giving older stems a dark-brown appearance.
Greyish-white leaves are alternate, simple and variable in shape. Basal leaves are deeply lobed or pinnatifid, 5-10 cm long and 1-2.5 cm broad, forming a quickly withering rosette. Lower stem leaves are lobed or sharply toothed. Upper leaves are entire, 1-3 cm long, linear to narrowly oblong with a sharp-pointed tip.
Flower heads are urn-shaped, 0.8-1.3 cm in diameter just above the base, solitary, and found at the tips of branches. Silvery buds form tubular pink or purple flowers that turn straw-coloured at maturity. The involucre is slenderly ovoid, pale, and about 1 cm high. Green outer floral bracts are rounded, ovate with clear, entire margins. Inner bracts are oblong-acuminate and cut-margined with hairy tips.
The achene is oblong, 2-3 mm long and 0.6-0.7 mm wide, greyish or ivory coloured, smooth with inconspicuous lines. It has a whitish, thread-like pappus at the apex that drops off when the seed matures (USDA, 1970;Watson, 1980;Roche and Roche, 1991).

Recognition


Monitoring is also important for control of R. repens. If possible, monitor three times a year: in the spring when plants have bolted, in the summer when flowering plants are easy to see, and in the autumn to find plants regrowing from roots. Disturbed areas such as roadsides are good targets (Woo et al., 1999;Zouhar, 2001).

Impact

R. repens is a deep rooted perennial that is native to Eurasia. It was accidentally introduced into North America as a contaminant of seed and spread rapidly. R. repens can be a serious crop pest in its native range and elsewhere. It forms large monotypic stands that reduce diversity and degrade forage quality on rangelands. As it is allelopathic and survives under a variety of conditions, it has been become an invasive exotic wherever it is imported. It has been declared a noxious weed in 18 US states (USDA-NRCS, 2016) and four Canadian provinces (Rice, 2003).

Hosts

R. repens is believed to be allelopathic and interferes with grain crops such as lucerne (Medicago sativa), wheat (Triticum species), barley (Hordeum vulgare) and oats (Avena sativa) (Heap and Mitchell, 1992). It spreads rapidly in good pastures and is a serious noxious weed of dryland crops in southern Russia (Watson, 1980).


Source: cabi.org
Description


Herbaceous vine, much branched from the base, climbs by means of tendrils and attains 1.5-2 m in length. Stems with 5 longitudinal ribs, glabrous or puberulent;cross section with a single vascular cylinder. Leaves alternate, biternate;leaflets chartaceous, puberulent or sparsely pubescent, the apex obtuse, acute, or acuminate, the base attenuate, the margins lobate or laciniate;terminal leaflet lanceolate or triangular, rhombic or narrowly lanceolate in outline, 2-3.5(5) cm long;lateral leaflets ovate, lanceolate, or oblong in outline, 1-2.5 cm long;rachis and petiole not winged;petioles 2-3 cm long;stipules lanceolate, approximately 5 mm long;tendrils in pairs, spirally twisted, at the end of short axillary axes (aborted inflorescences), from which an inflorescence usually develops. Flowers functionally unisexual, zygomorphic, in axillary racemiform thyrses, shorter than the accompanying leaf. Calyx light green, of 4 unequal sepals, the outer ones approximately 1.2 mm long, the inner ones 3-3.5 mm long. Petals white, obovate, 2.5-3.5 mm long;petaliferous appendages slightly shorter than the petals, fleshy and yellow at the apex, forming a hood that encloses the apex of the glands of the disc;disc unilateral, with 4 rounded or ovoid glands, approximately 0.4 mm long;stamens 8, the filaments unequal, pubescent;ovary trilocular, with one style and 3 stigmas. Capsules brown, pearlike, turbinate-obtriangular or sometimes nearly ellipsoid, 1.5-3 × 2-4 cm, pubescent. Seeds black, shiny, approximately 5 mm in diameter;hilum green when fresh, white when dry, cordate (Acevedo-Rodríguez, 2005;Flora of China Editorial Committee, 2015).

Impact

C. halicacabum is a long-lived scrambling, creeping, or climbing vine that is a weed of gardens, roadsides, disturbed sites and plantations. It has also the ability to climb and cover mature trees up to 8 m or more in height (Weeds of Australia, 2015). This species is often cultivated as an ornamental in gardens of tropical and subtropical regions of the world for its inflated balloon shaped fruits (Acevedo-Rodríguez, 2005;PIER, 2015;PROTA, 2015;Weeds of Australia, 2015). It has escaped from cultivation, and once naturalized it grows over native vegetation smothering trees, shrubs and understory vegetation. It is very successful invading forest margins, woodland, grassland, riverbanks, floodplains and rocky sites. Dense infestations can also impede access, increase the risk and intensity of fires and harbour pests and diseases (Invasive Species South Africa, 2015). Currently, C. halicacabum is regarded as a weed and invasive species in Australia, South Africa, Kenya, Tanzania, Uganda, French Polynesia, the Cook Islands, New Caledonia, Singapore, the USA, and Cuba (Foxcroft et al., 2003;Oviedo Prieto et al., 2012;BioNet-EAfrinet, 2015;PIER, 2015;USDA-NRCS, 2015;Weeds of Australia, 2015).

Hosts

C. halicacabum is a weed with substantial economic impacts on sugarcane and soyabean plantations (Gildenhuys et al., 2013).


Source: cabi.org
Description


From PROTA (2013)

Impact

E. hypericifolia is a herbaceous shrub native to the Americas. It is regarded as an invasive weed in many of the Pacific Islands in which it occurs, especially Hawaii, where it is rated ‘high risk’. It is also a weed in Singapore and Taiwan, though the situations in which it is causing problems are not well documented. It is recognized as a weed in soyabean, sugar cane and cotton in some countries and is presumably also threatening native flora in others.

Hosts

E. hypericifolia is recorded as a weed in soyabean, sugarcane and cotton.


Source: cabi.org
Description

Herbaceous, twining or creeping vine, attaining up to 6 m in length. Stems cylindrical, glandular- pubescent. Leaves alternate, 5-palmately compound;leaflets 1.5-7.5 x 0.7-3.5 cm, elliptical, ovate or ovate-lanceolate, the apex obtuse, the base acute or decurrent, the margins entire, undulate or dentate, glabrate or glandular-pubescent on both surfaces. Flowers in simple or double dichasial cymes;peduncles longer than the petioles;bracts persistent, linear to subulate;sepals subequal or unequal, 1-1.5 cm long, ovate to ovate-lanceolate, acuminate at the apex, glandular-pubescent;corolla funnel-shaped, white or sometimes pink, with or without a purple centre, 1.5-3 cm x 3-4 cm;stamens 5, white, sometimes with lilac anthers;stigma bilobed, white. Fruit capsular, 4-valvate, globose, 6-8 mm in diameter, light brown, glabrous, surrounded by the persistent sepals. Seeds 4 per fruit, ellipsoid, 5-6 mm long, dark brown, lanate (Acevedo-Rodríguez, 2005;Austin et al., 2012).

Impact

Merremia cissoides is a climbing weed native to tropical America that has been introduced to several Old World countries, presumably as an ornamental. It typically grows in disturbed areas and has been reported as a weed of several crops within its native range. However, it is not as widespread and common as other weedy species of Merremia. In several countries outside its native range, its occurrence has only been documented from one or few herbarium specimens. Nonetheless, the species is considered to be increasingly naturalized in the Old World tropics. It is invasive in Florida (USA) and Cuba.

Hosts

The species has been reported as a weed of sugarcane fields in Brazil (Perim et al., 2009;Correia and Kronka Júnior, 2010) and has also been reported in maize (Tavella et al., 2015), soybean (Timossi and Durigan, 2006), eucalyptus (Carbonari et al., 2010) and coffee plantations (Gavilanes et al., 1988).


Source: cabi.org
Description

Spermogonia and aecia are unknown.

Symptons

Infections occur mostly on leaves, often on petioles, and less frequently on stems. On susceptible species/cultivars, infections result in small yellowish-brown or greyish-brown spots or lesions (TAN-type), which, on soyabean [ Glycine max ], are delimited by the vascular bundles. On some hosts, spots are round rather than angular (Vakili and Bromfield, 1976). Pustules of urediniospores are formed on both the adaxial and abaxial surfaces of lesions, but are more frequent on the abaxial surface. The angular lesions coalesce, turn dark-brown and are covered by buff or pale-brown spore masses as sporulation progresses. When resistant species/cultivars are infected, minute angular reddish-brown spots (RB-type) appear, on which no or only a few uredinial pustules are formed. Sporulation on the RB-type lesions is much less than on the TAN-type lesions (Vakili and Bromfield, 1976;Bromfield et al., 1980;Bonde et al., 2006). Later in the season, lesions may become dark reddish-brown and crust-like;these contain subepidemal telial clusters. The telial stage has been found only occasionally on a few species and not on cultivated soyabeans in the field (Ono et al., 1992).

Impact

P. meibomiae is a rust native to the tropical and subtropical regions of the Americas that has a broad host range among legume species. It infects soyabean (Glycine max), but is less aggressive on that host than the Asian soyabean rust species, Phakopsora pachyrhizi, which has invaded and spread widely throughout the Americas. Due to the fact that the American species has not caused epidemics on soyabean in South America or invaded North America, it can be considered to be much less invasive than the Asian species. Given its broad host range, the possibility exists that strains of P. meibomiae could be a threat to other legumes cultivated in warm parts of the world.

Hosts


In the field, P. meibomiae infects and sporulates on 51 species in 20 genera of the subfamily Papilionoideae of the Fabaceae (Ono et al., 1992), with Aeschynomene americana, Canavalia villosa, Crotalaria anagyroides, Lablab purpureus, Phaseolus coccineus, Phaseolus lunatus and Phaseolus vulgaris being the principal hosts.
Neonotonia wightii is one of several alternate hosts of P. meibomiae in Brazil (Carvalho and Figueiredo, 2000).
In addition to these naturally-infected hosts, the following legume species have been shown to be susceptible to this rust species by artificial inoculations: Alysicarpus vaginalis;Cajanus cajan;Cassia occidentalis;Clitoria ternatea;Coronilla varia;Crotalaria spectabilis;Kummerowia stipulacea;Kummerowia striata;Lupinus albus;Lupinus luteus;Melilotus officinalis;Pisum sativum;Pueraria phaseoloides;Sesbania exaltata;Sesbania sericea;Trifolium incarnatum;Trifolium repens (Rytter et al., 1984);Calopogonium mucunoides;Crotalaria grantiana;Crotalaria juncea;Macroptilium atropurpureum;Macroptilium lathyroides;Vigna mungo;and Vigna aff. wilmanii (Ribeiro do Vale et al., 1985);Vigna unguiculata;and Phaseolus aff. longepedunculatus (Vakili and Bromfield, 1976). Although the level of susceptibility observed was low for some species, other isolates of the fungus or other test conditions might have produced more disease.
See Ono et al. (1992) for additional hosts, based on reports and specimens in collections.


Source: cabi.org
Description

P. angulata is an annual herbaceous plant, branched erect, with tap-roots, angled and hollow stems growing up to 1-2 m in height, although there are reports of plants growing only up to 50 cm tall (South Australia, 2012). It is usually hairless (glabrous);however, occasional plants have short hairs, especially on the younger parts (Hall et al., 1991).

Impact

P. angulata is a herbaceous annual species of American origin which has been very widely introduced across many tropical, subtropical and warmer temperate regions. It is often characterized as a pantropical invasive weed of crops, gardens and plantations, although in many regions it has naturalized (such as Central America, Africa, India and Pacific islands) (Raju et al., 2007). It is a host of the causal agent of tomato bacterial spot Xanthomonas campestris pv. vesicatoria, as well as viruses found in tobacco, potato, okra, capsicum pepper, lucerne, beans and several other crops, physalis mottle virus (PhyMV), and also several root-knot nematodes (Meloidogyne spp.). It is used in the traditional treatment of a wide variety of disease and consequently can be an economically beneficial plant. No detailed analysis of its impacts has been conducted.

Hosts

P. angulata has been found growing in maize, cotton and soybean fields and is now considered to be a widely-distributed invader in corn fields in Greece (Travlos et al., 2010;Travlos, 2012).


Source: cabi.org
Description


Adapted from Pitcher (1989)

Impact

X. spinosum is a highly invasive plant classified as one of the world’s worst weeds, and is now widely distributed throughout many regions of the world, where it is a common agricultural and pasture weed and a declared noxious species in many countries. Originating in South America, it has spread widely, probably via its spiked seeds which attach to animals and clothing or are a contaminant of hay or other products. It produces prolific amounts of seed that germinate easily. X. spinosum can quickly dominate large areas, outcompeting crops, forage plants and native flora. Control is possible but requires significant effort. There is considerable ongoing research into various methods including biological control.

Hosts

X. spinosum is recorded as a weed of cotton, maize, mungbean, sorghum, soyabean, sugarbeet, sugarcane, sunflower and tomatoes, as well as many other annual and perennial crops.


Source: cabi.org
Description

D. sissoo is a medium to large, deciduous, long-lived tree with a spreading crown and thick branches. It attains a height of up to 30 m and a girth of 2.4 m;the bole is often crooked. In Rawalpindi district, Pakistan, it also occurs in the form of a straggling bush at an altitude of 1500 m, clinging to crevices in the sides of sandstone cliffs (Troup, 1921). The bark is thick, rough and grey, and has shallow, broad, longitudinal fissures exfoliating in irregular woody strips and scales (Luna, 1996). D. sissoo develops a long taproot from an early age and has numerous lateral ramifying roots (Hocking, 1993). The leaves are compound, imparipinnate and alternate, with rachis 3.5-8 cm long, swollen at the base. There are 3-5 leaflets, each 3.5-9 x 3-7 cm;leaflets alternate, broadly ovate, conspicuously and abruptly cuspidate at the apex, rounded at the base, entire, coriaceous, pubescent when young and glabrous when mature. The terminal leaflet is larger than the others, and there are 8-12 pairs of veins in the leaflets (Parker, 1956;Luna, 1996). The inflorescence of D. sissoo is an axillary panicle 3.5-7.5 cm long, with small flowers, 7-9 mm long, white to yellowish-white with a pervasive fragrance, sessile, papilionaceous and hermaphrodite. The standard petal is narrow at the base and forms a low claw;wing and keel petals are oblong. Pods are 4.5-10 x 0.7-1.5 cm, linear-oblong, indehiscent, stipitate, glabrous, apex acute, reticulate against the seeds, and usually 1-4 seeded. Seeds are kidney-shaped, variable in size (8-10 x 4-5.5 mm), pale brown, brown to brownish-black, reniform, compressed, with papery testa (Parker, 1956;Singh, 1989;Luna, 1996).


Source: cabi.org
Description


Detailed descriptions and illustrations of F. auricularia are provided by Crumb et al. (1941), Behura (1956), and Lamb and Wellington (1975).

Recognition

F. auricularia is primarily a nocturnal species, hiding during daytime in dark places, where it tends to aggregate. Its presence in the agricultural environment can easily be established by looking under loose bark, stones, pots, wooden boards etc., or by providing artificial hiding places such as upturned flower pots filled with straw or cardboard. Using corrugated cardboard rolls or bands on trunks of trees or grapevines is an easy way to detect earwigs in orchards and vineyards. They can be easily seen on crop edges and on trees and vines when active and feeding at night (Department of Agriculture and Food, Government of Western Australia, 2015).
Despite the considerable size of last instars and adults detection is difficult in shipments. With vegetables, a sample will need to be cut open in order to reveal any hiding earwigs. Sometimes submergence of fruits and vegetables (e.g. cauliflowers) in cold water will drive earwigs out. Frequently they hide in the cores of apples and pears, in which case their presence can often be detected through frass and some external damage around the remnants of the calyx through which they usually enter the inside..
It is also difficult to detect contamination with earwigs in bulk loads, timber and balled up or potted plants.

Symptons

F. auricularia is a polyphagous generalist feeding on a wide range of crops, particularly fruits, vegetables and flowers. Most of the damage observed is caused by external feeding, resulting in partially destroyed or shredded plant parts. Feeding on tender plant parts often results in underdeveloped or malformed crops. On hops, earwigs have been observed to feed on young tender leaves (Theobald 1896). In corn (Zea mays) they feed on tender kernels but greater damage is caused by feeding on the silks, which leads to underdeveloped grains (Crumb et al., 1941). Sugar beets and mangels are damaged by feeding on both the roots and leaves (Lind et al., 1914, Lind et al., 1916). Cabbage varieties such as Savoy or cauliflower are prone to be affected by earwigs through direct feeding on the leaves, tunneling into the cabbage heads, and hiding and feeding inside. Other crops reported to be affected are peas, beans and tomatoes (Capinera, 2013). Occasionally, defoliation of potato plants takes place (Frank, 1896). Serious damage to seedlings is reported from cabbage, carrot and cucumber (Crumb et al., 1941). In flower production earwigs cause damage by feeding on various parts of the plants. Seedlings and flower buds are particularly affected, resulting in deformed blossoms (Crumb et al., 1941). There have been reports of earwigs damaging flowers of fruit trees such as plums (Theobald, 1896). In New Zealand, earwigs have been of economic concern by eating into peaches, nectarines and apricots rendering them useless for sale and in Chile damage to ripening cherries is problematic (Tillyard, 1925;Devotto et al., 2014). In Australia cherries are particularly affected;earwigs either eat directly into ripe fruits or damage the stalks of ripening cherries (Department of Agriculture and Food, Government of Western Australia, 2015. Damage to ripe apples and pears is sometimes reported (Capinera, 2013).

Impact


The European earwig, Forficula auricularia, is a polyphagous insect that is native to large parts of Europe and western Asia as far east as western Siberia. In the early twentieth century it was accidentally introduced into North America where it became widespread in a number of states/provinces of both the USA and Canada. It has also invaded Australia and New Zealand, and more recently Mexico, Chile and the Falkland Islands. Although economic damage to vegetable and flower gardens is generally minor, when high population densities occur it is a major pest in gardens and greenhouses, and a significant nuisance in households. Within and sometimes also outside its native range it is also regarded as a beneficial organism used or encouraged as a biological control agent to control other insect pests in orchards and gardens.

Hosts

F. auricularia is extremely polyphagous and has been reported to cause damage on a wide range of crops, in particular vegetables, flowers and stone fruits. Damage is mainly caused by external feeding of late instars and adults. Vegetables are mostly affected by external feeding externally on leaves, stems and stalks, and sometimes by penetrating the inside of crops such as cabbages and cauliflowers or feeding on seedlings and young plants (Frank, 1896;Lind et al., 1914, Lind et al., 1916;Crumb et al., 1941;Baker, 2009;Weems and Skelley, 2010;Department of Agriculture and Food, Government of Western Australia, 2015). In addition a wide variety of fruits can be affected by earwigs, with damage to stone fruits such as cherries, nectarines, peaches and apricots being more prevalent compared to apples and pears (Theobald, 1896;Tillyard, 1925;Crumb et al., 1941;Department of Agriculture and Food, Government of Western Australia, 2015).
In vineyards damage is caused by feeding on tender leaves, shoots and fruits (Huth et al. 2009;Department of Agriculture and Food, Government of Western Australia, 2015). The biggest problem with F. auricularia in vineyards is, however, their presence in harvested berries and the risk of tainting wine (Department of Agriculture and Food, Government of Western Australia, 2015).
The species can cause significant damage to flower production with dahlias, pinks, carnations, sweet William, zinnias and roses most frequently cited (Crumb et al., 1941;Weems and Skelley, 2010). Hops can be affected by feeding on tender leaves and shoots (Theobald, 1896). Among staple crops, damage has been reported from potatoes and corn (Frank, 1896;Coyne, 1928;Hearle, 1929;Eckstein, 1931;Weems and Skelley, 2010).

Biological Control
<br>The tachinid flies Triarthria setipennis and Ocytata pallipes are the two main parasitoids of F. auricularia in its native range. T. setipennis is generally the more abundant species, causing significantly higher infection rates. However, O. pallipes sometimes can exert high rates of parasitism;it seems to be better adapted to coastal climates and may in regions with maritime climates be equally suited for the control of F. auricularia (Phillips, 1983;Kuhlmann et al., 2001). Both species have been released repeatedly into the USA, Canada and New Zealand (Atwell, 1927;Davies, 1927;Crumb et al, 1941;Evans, 1952;Kuhlmann et al., 2001). Only T. setipennis is known to have established and spread to large areas of the USA and Canada (Dimick and Mote, 1934;McLeod, 1954;O’ Hara, 1996;Kuhlmann et al., 2001).<br>An intensive breeding and release program of T. setipennis originating from the Mediterranean region started in 1924 and lasted until the 1930s in Portland, Oregon, where it became well established (Dimick and Mote, 1934;Spencer, 1945). Since then, it has also established in Washington, California, Idaho, Utah, New Hampshire and Massachusetts (O’ Hara, 1996). It was also released in Connecticut and Rhode Island but has not been recovered there (O’ Hara, 1994).<br>In Canada, releases of T. setipennis were made in British Columbia (1934–1939), Ontario (1930–1941) and Newfoundland (1951–1953) using flies originating from Oregon (Getzendaner, 1937;McLeod, 1962). The species established in British Columbia and Newfoundland but did not reach high population densities (Mote, 1931;Dimick and Mote, 1934;Spencer, 1947), possibly due to poor adaptation to local climatic conditions (Kuhlmann et al., 2001). Additional releases of the species collected from climatically better matching sites in Switzerland, Germany and Sweden were made in the 1960s. New introductions into Newfoundland were followed by an average increase in parasitism (Morris, 1971, 1984;Morry et al., 1988), but in Nova Scotia, no establishment of T. setipennis could be confirmed (Kuhlmann et al., 2001). Five additional attempts were made in the 1980s to establish T. setipennis in the Ottawa area but it is not known whether it has established (Kuhlmann et al., 2001). The early studies on the establishment of T. setipennis in Newfoundland indicated a considerable reduction in earwig numbers, which was most probably due to high levels of parasitism in the mid-1970s (Morris, 1984;Kuhlmann et al., 2001). Since 1978, no further evaluation of parasitoid impact has been undertaken (Kuhlmann et al., 2001).<br>During the 1930s, some O. pallipes adults were released but only established temporarily in Oregon (Mote, 1931;Clausen, 1978). Pupariae of this species were also shipped to New Zealand for release there but whether the fly became established is not known (Davies, 1927;Evans, 1952). T. setipennis and O. pallipes have also been assessed for their suitability and safety to control F. auricularia on the Falkland Islands and both species are part of an on-going release programme (Maczey et al., 2016).<br>Details of the biology of T. setipennis and O. pallipes are provided by Thompson (1928), Mote et al. (1931), and Kuhlmann (1994, 1995).<br>Apart from the above-mentioned studies in Newfoundland, little information is available on how much effect these natural enemies have on earwig populations.

Source: cabi.org
Description

Ezzat (1956) and Green (1922) described I. insignis (as Orthezia insignis) in detail. Body of adult female is about 1.5 mm long and 1.3 mm wide (excluding the ovisac), brownish olive green;dorsum mostly bare of wax except for two narrow logitudinal rows of 12 small white wax processes, these rows situated on either side of the mid-line;the dorsal wax processes fairly short, the longest and most curled occurring towards the posterior end. Venter with white waxy areas around mouthparts and limb bases, and the white ovisac of sculpted wax arising from just posterior of the hind leg coxae and from a submarginal belt around the abdomen. Ovisac 1.5 - 3.5 mm long, of brittle wax plates, nearly parallel-sided, curving slightly upwards posteriorly, ending in a dorsal opening. Unlike most Coccoidea, I. insignis carries the ovisac attached to the body, rather than attaching it to the substrate. Antennae are 8-segmented, brownish, about 0.9 mm long, terminal segment longest. Eyes each situated on a conical projection just posterior to each antenna base.
Immature females lack any development of the ovisac but otherwise resemble smaller versions of the adult;first instar with body 0.3 mm long, antennae each 6-segmented, lacking ventral waxy areas and without bare area between dorsal rows of wax plates;second instar similar but larger;third instar larger again, with 7-segmented antennae and ventral waxy areas present.
Males are seldom produced (Green (1922) observed them produced at approximately four-year intervals in Sri Lanka). Adult male with body (excluding terminal wax filaments) 2.0 mm long;the single pair of wings appears greyish white with powdery wax;a pair of halteres present;antennae each 9-segmented, significantly longer than body, covered with short hairs;a pair of compound eyes present, each associated with a single ocellus;mouthparts absent;legs long and slender;abdomen terminates in a caudal tuft of white wax filaments arising from the antepenultimate segment.

Recognition


Examine shrubs or trees closely for signs of sooty mould or sticky honeydew on leaves and stems, or ants running about. Look for I. insignis on twigs and stems (and sometimes on the underside of leaf midribs);the white ovisacs of the adult females are easily seen, especially when they walk about and the moving ovisacs catch the light. Good light conditions are essential for examination;in poor light, a powerful flashlight is helpful.

Symptons

I. insignis extracts large quantities of sap, causing general host debilitation, but not death (Green, 1922). Build-up of sticky honeydew deposits occurs on nearby surfaces, which may attract attendant ants. Unsightly sooty moulds grow on the sugary deposits (Green, 1922), and badly fouled leaves may be dropped prematurely and the quality of fruits may be reduced. The older females are easy to see on young stems, especially when they walk about and the movement of the white ovisacs catches the light.

Hosts

I. insignis is polyphagous, usually preferring woody hosts, occurring mainly on the shoots and twigs. Ben-Dov et al. (1998) list hosts from 34 plant families. It is most often found on trees and shrubs of the Verbenaceae (especially Lantana, Clerodendron and Duranta species), Solanaceae (especially Capsicum and Solanum), Acanthaceae, Compositae (especially Eupatorium and other ornamentals) and Rubiaceae (including Coffea). Green (1922) remarked that, while I. insignis damages numerous ornamental plants in Sri Lanka, it was not a pest on tea or coffee. Ezzat (1956) successfully reared I. insignis on sprouting potato tubers in Egypt, where he recorded the pest damaging a wide range of crops and utility plants such as sugarcane, Citrus, potatoes, tomatoes, chrysanthemums, shade trees such as Jacaranda, and windbreaks such as Casuarina.


Source: cabi.org
Description


Larva
The larvae are dirty-white and somewhat transparent (so that the intestines can be seen). They have a bright reddish-brown head with one lateral ocellus at each side and clearly visible, brownish thoracic and abdominal plates. They are 21-26 mm long with a diameter of 3 mm. The presence of older larvae can be detected by characteristic masses of bore-meal and frass at the openings of boreholes.
Pupa
The pupae are brown, less than 10 mm long, and are formed in a cocoon, spun at the end of a mine, measuring 15 mm. As maturation approaches, the pupae work themselves partially out of the tissue to allow emergence of the adult. Two bent hooks, characteristic of the species, show at the end of the abdomen on the abandoned protruding pupal skin.
Adult
The adult is nocturnal, 11 mm long with a wingspan of 18-25 mm. It is bright yellowish-brown. The forewings may show longitudinal darker brown banding, and in the male a dark-brown spot towards the apex. The hindwings are paler and brighter (Süss, 1974;D'Aguilar and Martinez, 1982). At rest, the long antennae point forwards.

Recognition


On ornamental plants, O. sacchari is difficult to intercept at importation inspections, additional post-entry inspections are recommended.
On Strelitzia species, the larvae fed on the collar and roots of the plants (Porcelli and Parenzan, 1993).

Symptons


The early stages of larval tunnelling in woody or fleshy stems are practically undetectable. At a later stage, fleshy plants (cacti) may be completely hollowed out. In woody plants such as Dracaena and Yucca the larvae live on dead and living portions of the cortex and pith, and infested tissues may feel soft. Leaves wilt because the caterpillars destroy the xylem, and, in an advanced stage, leaves may fall and the plant may collapse. In Chamaedorea palms, the larvae typically feed at the base of the plant where the aerial roots enter the soil (Heppner et al., 1987).

Impact

O. sacchari was originally described from specimens from Mauritius. It is a tineid moth with typically Old World tropical distribution, thus populations could establish in the tropical belt and in areas with a mediterranean climate, also in glasshouses throughout the world. O. sacchari attacks a number of ornamental plants and can be transported on different plant parts. Although not listed on alert lists such as IUCN and ISSG, this species has the potential to be invasive outside its natural distribution area through the transport of ornamental plants and/or because of global warming.

Hosts

O. sacchari is found mainly in the tropics on bananas, pineapples, bamboo, maize and sugarcane in the field and on various stored tubers. In glasshouses in European countries, it has been found infesting various tropical or subtropical ornamentals, including mainly Cactaceae, Dracaena, Strelitzia and Yucca, but also occasionally Alpinia, Begonia, Bougainvillea, Bromeliaceae, Chamaedorea and other palms, Cordyline, Dieffenbachia, Euphorbia pulcherrima, Ficus, Gloxinia, Heliconia, Hippeastrum, Maranta, Philodendron, Sansevieria and Saintpaulia, and also Capsicum and aubergines. In import inspections, it is mainly Dracaena and Yucca which have been found to be infested.
The larvae are scavengers of dried/harvested vegetable material. This species may attack stored tubers (Gibbs, 1991) and feed occasionally on living plant material when adjacent to dried vegetable matter.


Source: cabi.org
Title: Sonchus asper
Description

This description was taken from the Flora of China Editorial Committee (2018)

Impact

Sonchus asper is an annual herb considered native to Europe, Africa and Asia that has been introduced to a wide range of countries around the world, where it frequently becomes an environmental and agricultural weed. The species grows in a wide range of habitats and climates, and produces large numbers of seeds (20,000 seeds), which are easily dispersed by wind and water, but also as contaminants. Because S. asper is very successful colonising disturbed sites, as well as natural habitats at early successional stages, it has the potential to outcompete native plant species, inhibit the establishment of other native pioneer species and thus alter natural successional processes. It is also regarded as a noxious species due to hosting diseases and pests that affect crops.

Hosts

S. asper has been listed as a weed of alfalfa, cotton, coffee, beans, garbanzo beans, tomato and maize plantations (Villaseñor and Espinosa, 1998;Vibrans, 2009).


Source: cabi.org
Title: Sonchus asper
Description

Annual herb, up to 4 m tall. Stems at first densely pilosulous with short hairs, in age glabrate;leaves alternate, petiolate, the blades rather thin, ovate to triangular-ovate, mostly 7-20 cm long, acuminate, cuneate (or sometimes almost truncate) at the base and then contracted and decurrent on the petiole, simple or sometimes trilobate, the margins serrate, hispid-pilose on both surfaces, especially on the veins, scabrous, glandular-punctate beneath;heads long-pedunculate;involucres 2-3 cm broad;phyllaries biseriate, 1.5-2.5 cm long, subequal or graduate, the outer ones lance-oblong to ovate-oblong, acute or acuminate, finely pilosulous, the herbaceous apex often lax or reflexed, the inner phyllaries similar but usually shorter;ray flowers 9-13, the ligules golden yellow or orange, 2-3 cm long;disc flowers yellow, the corollas puberulent, about 9 mm long;pales acuminate to cuspidate, hispidulous above, 12-18 mm long;achenes more or less appressed-pilose or glabrous, 6-7 mm long;pappus awns 2, early deciduous, or those of the outermost flowers sometimes wanting, 3-6 mm long, the squamellae united nearly to the apex, irregularly dentate, about 2 mm long (Nash, 1976).

Impact

Tithonia rotundifolia is an herbaceous flowering plant that has been widely introduced as an ornamental and has escaped from cultivation to become invasive mostly in ruderal areas, roadsides and in disturbed sites near cultivation. In this species, traits such as its rapid growth rates, abundant production of seeds that are easily dispersed by wind, water and animals, and high germination and recruitment rates are contributing to its invasiveness and allow it to quickly invade new habitats and survive even under less favourable conditions. T. rotundifolia forms dense stands with negative impact on native biodiversity as they outcompete and displace native vegetation, alter natural regeneration and obstruct access to riverbanks (Mawela, 2014;BioNET-EAFRINET, 2018;ISSA, 2018).

Hosts

T. rotundifolia is a weed of beans, chickpeas, tomato, and maize plantations. It is also listed as a weed of apple orchards and citrus plantations (Villaseñor and Espinosa, 1998;Vibrans, 2009).


Source: cabi.org
Description

D. caricosum is a perennial, stoloniferous grass. Culms tufted at nodes of stolons, geniculately ascending, 30–60 cm tall, nodes glabrous or pubescent. Leaf sheaths compressed, keeled, shorter than internodes;leaf blades flat, 15–20 cm × 2.5–5 mm, glabrous or with a few hairs at base, margins smooth or scabrid, apex acuminate;ligule less than 1 mm, margin ciliate. Inflorescence terminal;peduncle glabrous;racemes (1–)2–4, 2.5–5 cm, with 1–3 pairs of homogamous spikelets. Sessile spikelet 3–3.5 mm;lower glume obovate-elliptic or obovate-oblong, papery, 8–12-veined, glabrous or often sparsely hirsute on lower back, slightly glossy, margins shortly ciliate, keels winged, apex rounded;upper glume ciliate above middle, apex obtuse;awn 1.5–2.5 cm, weakly geniculate. Caryopsis obovate-oblong. Pedicelled spikelet many-veined, resembling sessile (Flora of China Editorial Committee, 2015).

Impact

D. caricosum has been intentionally introduced as a perennial grazing pasture with excellent ground cover. Now, it can be found widely naturalized in tropical and subtropical regions (Cook et al., 2005;FAO, 2015). It has escaped from cultivation and has become a weed and invasive grass in Cuba, Guam, New Caledonia, and Fiji (MacKee, 1994;Oviedo Prieto et al. (2012);PIER, 2015). In Cuba, it is widespread across the islands. In Fiji, it covers large areas being very common especially in the dry zones, in pastures, canefields, waste places, and along roadsides (Smith, 1979). D. caricosum is a fast-growing gregarious grass that competes aggressively with other plants including other weeds (Cook et al., 2005).

Hosts

D. caricosum is a common weed with negative impact in pastures and sugarcane fields (Smith, 1979).


Source: cabi.org
Description

M. eruciformis is an annual terrestrial herb growing up to 45 cm tall and forming dense clusters of 10-60 cm long reclining and slender stems, with softly hairy culms rooting at the lower nodes. Stem internodes are hollow.

Impact

Moorochlora eruciformis is an annual herb, fodder crop and common agricultural weed, native to Africa, Asia and the Mediterranean;it has also been introduced to the Americas and Oceania. Crop seed contamination is a possible pathway for dispersal of this species. It is reported as invasive in Cuba, Spain and Australia as well as islands in Oceania. Despite this, there is limited information available about the economic and environmental impacts of this species or its dispersal potential.

Hosts

It is a common weed species in cultivated fields, particularly associated with maize, sugarcane and coffee crops (Holzner and Numata, 1982;Blanca et al., 2009;Afridi et al., 2015).


Source: cabi.org
Description


The following information is adapted from Puff (1991), Nelson (1996) and Wagner et al. (1999), and modified by the datasheet author using plant specimens from warm temperate (Jacono 952, FLAS) and subtropical (Howell 1285, FLAS) regions of Florida.

Recognition


Detection of P. foetida in the field or during inspection at ports of entry can easily be made based on the following features: a slender vine with opposite, oblanceolate, sometimes nearly heart-shaped, soft green leaves having a stipular tab on the stem between the petioles, the leaves producing a foul-smelling sulfurous odour when bruised, and fruits, if present, the size of a peppercorn, with a thin, brittle skin orange to brown in colour and splitting to release no more than two seeds.

Impact


A perennial vine of South-East and East Asian origin, Paederia foetida has characteristically opposite, soft and offensively smelling leaves, and produces solitary flowers and globose fruits in a ‘double scorpioid’ inflorescence. Vines trail across the ground, clamber over shrubs and twine into tree canopies to form curtains of dense vegetation that blo