Soil

Q&A

Soil
Description

E. guineensis is a monoecious, erect, one-stemmed palm tree, usually 20Ð30 m high, with an adventitious root system that forms a dense mat in the upper 35 cm of the soil with only a few roots penetrating deeper than 1 m. The stem is cylindrical, up to 75 cm in diameter and covered with petiole bases in young palms, smooth in older trees (10Ð12 years old). Juvenile leaves are lanceolate and entire but gradually becoming pinnate;mature leaves spirally arranged, paripinnate, up to 7.5 m long;petiole 1Ð2 m long, spinescent, clasping the stem at base;leaflets linear, 35Ð65 x 2-4 cm, up to 376 per leaf. Inflorescences are unisexual, axillary, pedunculate, until anthesis enclosed in two fusiform or ovate spathes 10Ð30 cm long, with flowers 3-merous;male ones with numerous cylindrical spikes forming an ovoid body 15Ð25 cm long and bearing flowers with 6 stamens, connate at base, with linear anthers;female ones subglobose, 15Ð35 cm diameter, with numerous lanceolate, spiny bracts, each subtending a cylindrical spikelet with 10Ð20 spirally arranged female flowers, each with two rudimentary male flowers;stigma sessile, 3-lobed. Fruits are ovoid-oblong drupes, 2Ð5 cm long, tightly packed in large ovoid bunches with 1000Ð3000 fruits;drupes with a thin exocarp, an oleiferous mesocarp and a lignified endocarp containing the kernel with embryo and solid endosperm.


Source: cabi.org
Soil
Description

R. oleracea grows up to 40 m tall, with a distinctive, solitary, light gray, erect, cylindrical trunk up to 22 m. Its appearance has been described to be like a marble column (Zona, 1996). Leaves are in the crown at the top of the stem. Flowers are borne in large stalked panicles revealed when the leaf-sheaths beneath them drop off;abundant blue-violet fruit are small, obovoid and without stalks. The fruits turn purplish-black when ripe (Palmpedia, 2014). The roots can often be seen emerging from the stem just above the soil level. Individual trees have 16-22 or 20-22 leaves, 3-5 m long with leaflets of about 1 m in two horizontal ranks;leafstalks about 1.5 m long, broadening to surround and sheath stem Leaf segments are arrayed in two planes on either side of the rachis, however, in the past there was some disagreement in the literature on this characteristic. The species is noteworthy and relatively easy to identify for several reasons, one being that the leaves of the crown typically do not hang much below the horizontal, unlike other species in which the leaves droop and obscure the shaft of the crown. The species is also distinguished within its genus for an unopened peduncular bract which is strongly clavate with an acuminate tip. Groups of rachillae are undulate, forming wavy curves with amplitudes of 4 cm or more (Zona, 1996).


Source: cabi.org
Soil
Description

Variable in habit, often epiphytic, subscandent shrubs when young, in maturity spreading evergreen trees with large branches and numerous aerial roots hanging from the trunk and branches, these sometimes reaching the soil to form pillar-like roots. Leaves: variable, coriaceous, oblong, elliptic to broadly elliptic or obovate, usually 5-8 cm long, 3-5 cm wide, glabrous, margins entire, petioles 0.6-2 cm long. Flowers: synconia sessile, arising among or just below the leaves, depressed-globose, 6-10 mm in diameter, subtended by 3 broadly ovate, ± persistent bracts.


Source: cabi.org
Soil
Title: Populus nigra
Description

P. nigra var. italica is a deciduous tree, with a narrow columnar crown. The trunk is straight with suckers at the base. The root system is lateral, shallow or deep, depending on soil layer and depth of water table, and can be invasive and problematical if trees are planted near buildings. The bark is more or less dark brown, thin and easily damaged.


Source: cabi.org
Title: Populus nigra
Soil
Title: Ficus carica
Description

F. carica trees can range from open to compact and from pendulous to upright to spreading, depending on the specific cultivar. Tree size and tree density are also rather dependent upon the cultivar, although cultural factors and soil quality can have a substantial impact upon eventual tree size. Exceptional specimens exist that have attained from 9 to 12 m in height and 10 m in spread, although commercially grown trees might only average from 5 to 8 m in height and from 6 to 7 m in width in the widest set plantings. Some cultivars produce trees that are round-topped and dense with many twiggy lateral spurs. Other cultivars have more apically dominant branches with fewer spurs, producing a more open or leggy appearance (Janick and Paull, 2008).


Source: cabi.org
Title: Ficus carica
Soil
Description

The olive is a long-lived evergreen tree. Its dimensions and shape vary with climatic conditions, soil fertility, cultivar and cultural practices. Trees growing in the wild exhibit a shrub habit of growth and can reach a height of 10 m. Although when pruned, cultivated olive could reach 15 m. It is able to develop suckers and roots from temporary buds generated by neoplasm formation in the base of the trunk just below the soil surface. These formations are known as 'ovules' and are of considerable importance in conserving the tree as they continue to form and grow as the tree becomes old. The root system is extensive, depth and lateral spread of the root system depends on soil type and depth, aeration and water content.


Source: cabi.org
Soil
Description

Kudzu is a perennial climbing vine that produces very large tubers up to 2 m long and 18-45 cm wide that can weigh as much as 180 kg on old plants. Stems or branches are strong, approximately 0.6-2.5 cm in diameter and up to 30 m in length. They can grow up to 25 cm per day or 18 m per growing season, and produce root crowns where nodes contact soil. Leaves are pinnately trifoliate, 8-20 cm long and 5-19 cm wide with leaflets ovate to orbicular and unlobed to trilobed. Leaves are pale green above and light to greyish green below. Purple to blue flowers, that smell of grapes, are borne on a mostly unbranched inflorescence 10-25 cm long. Seeds are borne in golden-haired, brown, flattened, oblong pods, 4-13 cm long and 0.6-1.3 cm wide. The seeds, visible through the pod, are flattened, ovoid and reddish brown with a black mosaic pattern. They are approximately 4-5 mm long by 4 mm wide and 2 mm thick (van der Maesen, 1985). For a more detailed description and a key to the three varieties, see van der Maesen (1985).


Source: cabi.org
Soil
Description

Non-woody vine, twining (toward the right), glabrous, attaining 10Ð15 m in length. Root system fibrous, shallow, mostly confined to the top 1 m of the soil. Tubers usually single, varying in size and shape, often very large;cylindrical or clavate in shape (often found as deep as 1.5 m) or globose, stout and short, pyriform, often variously lobed or fingered and fasciated or curved;skin brown to black;flesh white, cream or purplish (superficially or throughout). Stems are quadrangular, with 4 longitudinal winged, undulate, green or reddish projections;mature stems (at the base) cylindrical and spiny. Leaves are mostly opposite, sometimes alternate on branches of rapid growth, coriaceous, broadly ovate, 5- to 7-veined, 10Ð30 x 5Ð18 cm, the apex acute or acuminate, sometimes reflexed, the base cordiform;upper surface dark green, shiny, with the venation sunken;lower surface pale green, dull, with prominent venation;petioles 4Ð12 cm long, 4-winged, forming an auriculate sheath at the base, with a pair of pseudostipules that clasp the stem;bulbils elongate, pendulous, attaining 15 cm long, produced when the leaves begin to wither. Inflorescences are axillary, unisexual, pendulous. Staminate inflorescences are paniculate, 5Ð15 cm long, with numerous lateral and flexuous spikes that contain numerous male flowers. Pistillate inflorescences are racemose, with few flowers. Perianth 1Ð1.5 mm long in staminate flowers;2Ð2.8 mm long in pistillate flowers. Fruit a 3-locular capsule, 2Ð3 cm wide, each locule flattened like a wing, with two seeds inside (Acevedo-Rodr’guez, 2005). Seed orbicular, winged all round.


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

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


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

B. caryophylli is a straight or slightly curved rod with rounded ends, occurring singly or in pairs;it is aerobic, non-sporing, motile with one or several polar flagella, Gram-negative, sudanophilic, 0.35-0.95 x 1.05-3.18 µm.
In PDA culture, colonies are round, smooth and shining with regular margins: while cream-coloured at first, colonies darken with age. On nutrient agar, growth is slow and cells die rapidly;subculturing is not possible after about a week.

Recognition


To make a reliable diagnosis, many old and young stems should be examined and isolations made from diseased tissue. Microscopic observation of stem sections shows neoformations around infected vessels, plugging of vessels, hyperlignification of their walls and necrosis. Since latent infections on cuttings cannot be readily detected, cuttings should be kept at a relatively high temperature to ensure maximum symptom expression. The bacterium can be reliably detected by immunofluorescence staining (IFAS) and direct isolation even in material with latent infection (Muratore et al., 1986). B. caryophylli has also been detected from inoculated carnation by PCR and LAMP (Loop-mediated isothermal amplification) (Kazushi et al., 2005).

Symptons


Symptoms may take 2-3 years to manifest themselves, particularly when cuttings are mildly infected and maintained at relatively low temperatures. Foliage becomes greyish-green, later yellowing and wilting and then death may occur.
In stems, at soil temperatures below about 17°C, a rapid multiplication of cells leads to tension around the vessels and longitudinal, internodal stem cracks appear, usually at the base of the plant, and later develop into deep cankers. Initially, this cracking is very similar to the physiological cracking observed in certain cultivars. However, in pathogen-induced cracks, a brownish-yellow bacterial slime is visible, often overgrown with saprophytic fungi such as Mycosphaerella tassiana. In some cases, the extrusions from the cankers leave the stems hollow. At 20-25°C, cankers are more rare and wilting is the common symptom. Visual observation of peeled stems reveals sticky, brownish-yellow, narrow or broad, longitudinal stripes in the vascular tissue;in cross section, these appear as irregular brownish spots with a water-soaked margin.
Roots of infected plants, once wilting occurs, are more or less rotten, the plants being easily pulled out of the soil and, on cutting, roots show discontinuous brown spots which distinguish the disease from that caused by Phialophora cinerescens which leaves the roots apparently symptomless (EPPO/ CABI, 1996a).
Plants may survive about 1-2 months, but secondary invasion by fungi, such as Fusarium spp., accelerates death. Heavily infected cuttings wilt and die before roots are formed. For more information, see Dimock (1950), Hellmers (1958), Lemattre et al. (1964), Garibaldi (1967), Lemattre (1969) and Saddler (1994).

Hosts


Carnations are the main host. However, Dianthus barbatus and D. allwoodii can be infected through artificial inoculation. In Florida, USA, and Japan, Limonium sinuatum is also reported to be infected (Jones and Engelhard, 1984;Nishiyama et al., 1988).


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
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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
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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
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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
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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
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Summer
Soil Tolerances
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Soil drainage
impeded
seasonally waterlogged
Soil texture
heavy
medium
Natural enemies
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Natural enemy|Type|Life stages|Specificity|References|Biological control in|Biological control on
Hypochniciellum ovoideum| Pathogen
not specific
Notes on Natural Enemies
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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

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

A. syriaca (common milkweed) is a perennial herb with long-spreading rhizomes. Stems stout, erect, to 2 m tall, with short downy hairs and milky juice;leaves opposite, smooth margined, oblong, 10-20 cm long and 5-11 cm wide, with prominent veins;upper surface smooth, lower covered with short white hairs. Flowers sweet-smelling, pink to white, in large, many-flowered (the number per inflorescence varies greatly, from less than 10 to more than 120) axillary and apical bell-like clusters. The long-lived flowers produce copious amounts of nectar (Wyatt and Broyles, 1994), flowering from June to August, depending on initial growth, climate, and location (Anderson, 1999). Seed brown, flat, oval, 6 mm long, 5 mm wide, with a tuft of silky white hairs apically. All plant parts contain latex;shoots from established plants arise from adventitious root buds, emerging in April and May. The root system is composed of horizontal and vertical roots. In established stands, vertical roots may penetrate the soil to depths of 3.8 m (Anderson, 1999).

Impact

A. syriaca can be an aggressive and persistent weed and contains several poisonous glucosidic substances (cardenolides) known to be poisonous to sheep, cattle, and occasionally horses (Anderson, 1999).

Hosts

The crops most affected by this species are soybeans, corn, peanuts and grain sorghum (Anderson, 1999) and maize (Konstantinovic et al., 2008). Canadian studies of c ompetition between common milkweed and oats found up to 20% yield loss of grain (Bhowmik, 1982).


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

C. dactylon is a perennial grass, with underground rhizomes and on the ground runners (Cabrera, 1968;Covas and Salvai, 1970). The runners spread horizontally and bear nodes with internodes of about 10 cm length. They may be flattened or cylindrical, mostly unhaired. Each node roots in the soil and produces short culms (tillers), up to 25 cm high, but develop into prostrate runners under less dense conditions. The almost unique character of the Cynodon genus of at least two and often three leaves at each node can be seen on the extended runners. This immediately distinguishes it from other perennial weeds with comparable growth pattern such as Panicum repen s and Paspalum distichum (Perez and Labrada, 1985).
The rhizomes are mainly in the top 10 cm of the soil but may penetrate to a depth of 35 cm (Perez and Labrada, 1985;Phillips and Moaisi, 1993).They may be twice as wide as the runners and this is one of the variable characters in populations (0.2-0.9 cm). Each node is covered by a white cataphyl. Runner or rhizome nodes may bear up to three viable buds.
Leaves have an alternate-distal pattern of distribution along the runners. Leaf blades are open up to the base, unhaired, similar or shorter than the length of the internode. The ligule is very short but with a conspicuous fringe of white hairs. Leaf blades are green to dull-green, from 1 to 15 cm depending on node, lanceolate, and forming almost a 90° angle with the leaf blade, finely parallel-ribbed on both surfaces, without a conspicuous midrib (Rosengurt et al., 1960). The width and pilosity of the weed blade may be used to distinguish populations of the weed (Oakley, 1999).
The inflorescence is supported on a culm up to 25 cm high and consists of a single whorl of 3-7 narrow racemes, each 3-8 cm long. Spikelets are 2-2.5 mm long in two rows, closely appressed to the rachis. Glumes are one-nerved, the lower almost as long as the spikelet, the upper half to three-quarters as long. The lemma is silky pubescent on the keel, palea glabrous. Caryopses are sub-eliptical, compressed and brownish, brilliant coloured (Kissmann, 1991).
The seedling has a hairy ligule, bearing 0.5 mm hairs. Pilosity increases as the seedling grows.

Impact

C. dactylon is a stoloniferous grass widely naturalized in tropical and subtropical regions of the world. This species is a C 4 grass included in the Global Compendium of Weeds (Randall, 2012) and it is listed as one of the most “serious” agricultural and environmental weeds in the world (Holm et al., 1977). It is a fast-growing grass that spreads by seeds and stolons and rapidly colonizes new areas and grows forming dense mats. As with many other African grasses, this species has the potential to alter ecosystem functions by altering fire regimes, hydrological cycles, biophysical dynamics, nutrients cycles, and community composition (D’ Antonio and Vitousek, 1992). C. dactylon is very drought tolerant by virtue of rhizome survival through drought-induced dormancy over periods of up to 7 months. After dormancy, it has the ability to easily re-sprout from stolons and rooted runners. Plants also recover quickly after fire and can tolerate at least several weeks of deep flooding (Cook et al., 2005). Currently, C. dactylon is listed as invasive in many countries including Australia, Indonesia, Singapore, Cambodia, Vietnam, USA, Mexico, Costa Rica, Puerto Rico, Chile, Colombia, Uruguay, Argentina, Brazil and many islands in the Pacific Ocean such as Hawaii, Fiji, and French Polynesia among others (see distribution table for details).

Hosts

C. dactylon is treated by Holm et al. (1977) as the second most important weed in the world (after Cyperus rotundus), a status justified by its occurrence in virtually every tropical and subtropical country and in virtually every crop in those countries. In Holm et al. (1979) it is listed as a 'serious' or 'principal' weed in no less than 57 countries. A list of crops in which C. dactylon is, or could be, a problem weed would include virtually every crop of the tropics and subtropics and most temperate crops. The crops in which it is most commonly a major problem are those of the subtropics that are planted in wide rows, for example, cotton, sugarcane, tobacco, citrus, olive, deciduous fruit, forestry and ornamental species and many vegetables, but also some closer-planted but less competitive crops such as rice, lucerne, mixed lucerne and grass pastures, onion and jute (Labrada, 1994).


Source: cabi.org
Description

E. indica is a tufted annual grass, prostrate and spreading, or erect to about 40 cm, depending on density of vegetation but not usually rooting at the nodes. The root system is very well developed and strong and the name jongos gras, used in South Africa, implies that it takes a young ox to uproot it. On germination, the first leaf, about 1 cm long, tapers very suddenly to a point and may be pressed quite flat on the soil. Later leaves are flat to V-shaped, up to 8 mm wide, 15 cm long and come to a longer, acute, boat-shaped tip. They are glabrous and usually quite bright, fresh green in colour. The ligule is a very short membraneous rim up to 1 mm long, sparsely fringed with short hairs. The sheaths and stem bases are distinctly flattened. The inflorescence consists of 3-8 racemes, each 5-10 cm long, about 5 mm wide, arranged more-or-less digitately, though one raceme may be inserted about 1 cm below the others. The narrow rachis, about 1 mm wide, has two dense rows of almost glabrous spikelets, each 2.5-3 mm long, 3-5 flowered, the lower and upper glumes about 1.5 and 3 mm long, respectively, and the lemmas very similar in both texture and size to the upper glume. All have a slightly scabrid keel and are acute but not awned. The reddish-brown to black seeds are oblong, about 1 mm long, conspicuously ridged.

Impact

E. indica is primarily listed as an agricultural and environmental weed (Randall, 2012) and is considered a “serious weed” in at least 42 countries (Holm et al., 1979). This species is described as a “dominant weed” especially in farming systems and annual row-crops where it grows vigorously and produces abundant seedlings (Holm et al., 1979). A single plant may produce more than 50,000 small seeds, which can be easily dispersed by wind and water, attached to animal fur and machinery and as a contaminant in soil (Waterhouse, 1993). E. indica invades disturbed habitats in natural areas and the margins of natural forests and grasslands, marshes, stream banks and coastal areas. It is also a common weed along roads, pavements, and powerline corridors (Queensland Department of Primary Industries and Fisheries, 2011). Currently it is listed as invasive in several countries in Europe, Asia, Central and South America, the Caribbean and on many islands in the Pacific Ocean (see Distribution Table for details).

Hosts

E. indica may occur in virtually any annual crop in the tropics and sub-tropics and also in many perennial crops and pastures. It is perhaps most conspicuous in annual row-crops such as cereals, legumes, cotton, tobacco and vegetable crops in which it is able to establish rapidly before there is adequate shading from the crop.


Source: cabi.org
Description

The plant is a vigorous growing herbaceous perennial with annual tubular, glabrous stems that ascend from an erect base. These stems are light green often with reddish flecks, branched and reach up to 3 m in height (Beerling et al., 1994). Where introduced, F. japonica is generally taller than in its native range in Japan (Holzner and Numata, 1982), where it is recorded as being 0.3-1.5 m tall (Makino, 1997). Stems arise from strong rhizomes to form a dense thicket. Rhizomes are thick and woody when old, and have been recorded as spreading 5-7 m laterally (Pridham et al., 1966). The rhizome has ring-like structures at about 2 to 4 cm intervals which are reduced leaf scales, whilst on the underside are adventitious roots travelling into the soil. The rhizome snaps like a carrot when fresh to reveal a yellow/orange colour. The main aerial shoots emerge from the large bulbous rhizome crown about 30 cm x 30 cm across. This acts as a carbohydrate store in the winter months when it represents the complete live biomass of the plant. Spreading out from this central region are a number of radial penetrating rhizomes that twist together to form a sizeable and considerable penetrating force. The leaves are 5-12 cm x 5-8 cm, broadly ovate, cuspidate at the tip and truncate at the base. At the base of each leaf petiole is located a small gland that functions as an extra-floral nectary. The flowers are off-white and borne in ochreate clusters of 3 to 6 on terminal and axillary panicles, with the main axis up to 10 cm long and with slender branches 5-9 cm long (Lousley and Kent, 1981). Sepals 5, the outer 3-keeled;stamens 8, included within a perianth in male-sterile plants, filaments 0.4 mm, anthers small, flat, empty 0.3 mm, styles 3, distinct, stigma fimbriate, exceeding the perianth;perianth greatly enlarged in fruit and conspicuously winged, completely enclosing the trigonous achene. Achenes (or nuts) 2-4 mm long, 2 mm wide, dark brown and glossy, mean weight 1.6 mg. Inflorescences initially erect but drooping at maturity. Male fertile plants are not known from the introduced range.

Recognition


The UK Environment Agency have produced a Code of Practice, and the Cornwall and Devon Knotweed Forum have produced an excellent guide which has advice on identifying the plant in the field at various stages of the season. as have the British Columbia Ministry of Forest and Range.

Impact

F. japonica is an extremely invasive weed despite its lack of extensive sexual reproduction in most of its introduced range. It is included on various lists of invasive weeds and is one of the 100 worst invasive species as identified by the IUCN. It is a potential contaminant of soil, and its ability to tolerate a remarkable range of soil types and climates means that it has the potential to spread much further than it has to date. It has gained a fearsome reputation for breaking through hard structures in the built environment and being almost impossible to eradicate once it has taken hold and is often recognized as one of the most pernicious weeds in any recipient country.

Hosts


Amphibians have been shown to have reduced foraging success in knotweed patches (Maerz et al., 2005) and any native species forced to compete with knotweed, i.e riparian plants, are likely to suffer consequences, as demonstrated by Gerber et al. (2008).


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
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Plant name|Family|Context
Oryza sativa|
Zea mays subsp. mays (sweetcorn)|Poaceae
Biology and Ecology
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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
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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
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Latitude North (°N)|Latitude South (°S)|Altitude Lower (m)|Altitude Upper (m)
40
40
0
0
Soil Tolerances
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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
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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
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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
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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
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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
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Category|Impact
Economic/livelihood
Positive and negative
Environment (generally)
Positive and negative
Economic Impact
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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

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

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

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

A. fulica is distinctive in appearance and is readily identified by its large size and relatively long, narrow, conical shell. Reaching a length of up to 20 cm, the shell is more commonly in the size range 5-10 cm. The colour can be variable but is most commonly light brown, with alternating brown and cream bands on young snails and the upper whorls of larger specimens. The coloration becomes lighter towards the tip of the shell, which is almost white. There are from seven to nine spirally striate whorls with moderately impressed sutures. The shell aperture is ovate-lunate to round-lunate with a sharp, unreflected outer lip. The mantle is dark brown with rubbery skin. There are two pairs of tentacles on the head: a short lower pair and a large upper pair with round eyes situated at the tip. The mouth has a horned mandible, and a radula containing about 142 rows of teeth, with 129 teeth per row (Schotman, 1989;Salgado, 2010). Eggs are spherical to ellipsoidal in shape (4.5-5.5 mm in diameter) and are yellow to cream in colour.

Recognition

A. fulica is a large and conspicuous crop pest which hides during the day. Surveys are best carried out at night using a flashlight. It is easily seen, and attacked plants exhibit extensive rasping and defoliation. Weight of numbers can break the stems of some species. Its presence can also be detected by signs of ribbon-like excrement, and slime trails on plants and buildings.

Symptons

In garden plants and ornamentals of a number of varieties, and vegetables, all stages of development are eaten, leading to severe damage in those species that are most often attacked. However, cuttings and seedlings are the preferred food items, even of plants such as Artocarpus which are not attacked in the mature state. In these plants damage is caused by complete consumption or removal of bark. Young snails up to about 4 months feed almost exclusively on young shoots and succulent leaves. The papaya is one of the main fruits which is seriously damaged by A. fulica, largely as a result of its preference for fallen and decaying fruit.
In plants such as rice, which are not targets of A. fulica, sometimes sheer weight of numbers can result in broken stems. In general, physical destruction to the cover crop results in secondary damage to the main crop, which relies on the cover crop for manure, shade, soil and moisture retention and/or nitrogen restoration. This in turn can result in a reduction in the available nitrogen in the soil and consequently marked erosion in steeper areas.

Impact


The giant African land snail A. fulica is a fast-growing polyphagous plant pest that has been introduced from its native range in East Africa to many parts of the world as a commercial food source (for humans, fish and livestock) and as a novelty pet. It easily becomes attached to any means of transport or machinery at any developmental stage, is able to go into a state of aestivation in cooler conditions and so is readily transportable over distances. Once escaped it has managed to establish itself and reproduce prodigiously in tropical and some temperate locations. As a result, A. fulica has been classified as one of the world's top 100 invasive alien species by The World Conservation Union, IUCN (ISSG, 2003).

Hosts

A. fulica is a polyphagous pest. Its preferred food is decayed vegetation and animal matter, lichens, algae and fungi. However, the potential of the snail as a pest only became apparent after having been introduced around the world into new environments (Rees, 1950). It has been recorded on a large number of plants including most ornamentals, and vegetables and leguminous cover crops may also suffer extensively. The bark of relatively large trees such as citrus, papaya, rubber and cacao is subject to attack. There are reports of A. fulica feeding on hundreds of species of plants (Raut and Ghose, 1984;Raut and Barker, 2002). Thakur (1998) found that vegetables of the genus Brassica were the most preferred food item from a range of various food plants tested. However, the preference for particular plants at a particular locality is dependent primarily on the composition of the plant communities, with respect to both the species present and the age of the plants of the different species (Raut and Barker, 2002). Crops in the Poaceae family (sugarcane, maize, rice) suffer little or no damage from A. fulica.
Given the polyphagous nature of A. fulica any host list is unlikely to be comprehensive. Those plant hosts included in this datasheet have been found in literature searches and Venette and Larson (2004).


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

S. nigrum is a very variable ephemeral, annual or sometimes biennial herb, 0.2–1.0 m tall, reproducing only by seed. It has a strong white taproot, with many lateral roots being produced in moist and fertile surface soils.
Stems vary from prostrate to ascending or erect, and from herbaceous in ephemeral plants to rather woody or even shrubby in those that survive long enough to be biennial. Stems are round or angular, smooth or sparsely hairy, and green to purplish.
Leaves are alternate, ovate and are carried on short stalks, 2–8 cm long, and vary between plants from smooth-edged to shallowly lobed. They are opaque, matt and dark green both above and below, and either smooth or finely hairy.
The small, white, star-shaped flowers are carried in umbels on slender stalks developing directly from the stems between the leaves. Each cluster usually carries from 5–10 flowers, which open sequentially over several days. The flowers are 5-8 mm across, and have prominent yellow centres.
Fruits are globular, dark green, matt berries 5–13 mm across, matt black when ripe, which contain many flattened, finely pitted, yellow to dark brown woody seeds approximately 1.5 mm long.
Seedlings of S. nigrum agg. all exhibit epigeal germination. The hypocotyl is commonly slender, about 1 cm long, green or purplish and distinctly hairy. The spreading cotyledons are slender, about 5 mm long, and taper towards the tips. The epicotyl is slender, smooth to finely hairy, and carries small, ovate, juvenile leaves that gradually assume the adult shape and size.


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


Description taken from GrassBase (Clayton et al., 2006) with minor modifications from Godfrey and Wooten (1979) and from material reviewed by the author

Recognition


Separating P. geminatum from other tribes of grasses:
P. geminatum is perennial, does not form a winter rosette, and its basal leaves do not differ from stem leaves. The infloresence consists of several spike-like racemes along a main axis;rachis of racemes somewhat flattened, ending in a short, naked point (not a bristle);spikelets glabrous, fruits transversely rugose.
Separating P. geminatum from other Panicum in the tribe Geminata:
P. geminatum is glabrous throughout, nodes glabrous. Spikelets to 3.3 mm;glumes and sterile lemma not papery.
Determining P. geminatum:
The ligule is a ring of hairs to 1 mm long. Leaf sheaths compressed. Leaf blades flat medially, linear, the long-tapering tips involute;blades mostly glabrous or with minute hairs at base of upper surface. Infloresence up to 30 cm long and bearing 6 to 20 alternating, short-ascending or appressed-ascending flattish, spike-like fertile branches. The rachis is sharply 3-angled and ends in a short naked point, not a bristle. Spikelets planoconvex or nearly so, 2.2 to 3.3 mm long, arranged alternately in two rows on one side of the sharply 3-angled rachis. Spikelets are ovate to oblong-elliptic in shape. The first glume is short, as broad as it is long or broader than it is long.

Impact

P. geminatum is a globally-distributed grass that is an important component of marshes and emergent grasslands in tropical, dry, and warm temperate climates defined by well-marked dry and rainy seasons. P. geminatum contributes to unique and diverse wetland communities. It can become locally abundant under extended warm season flooding, but is not considered introduced, invasive, or problematic in these natural environments. P. geminatum has become problematic in arid climates where urbanization, irrigation and drainage projects have caused massive alterations in soil and hydrologic regime. It can spread through irrigation canals, open waste ditches and polluted riparian systems, compromising water flow and flood control.


Source: cabi.org
Description


Plant: T. diversifolia is 2-3 m tall with upright and sometimes ligneous stalks. It forms woody shrubs.

Impact

T. diversifolia, commonly known as the tree marigold, is a herbaceous flowering plant in the Asteraceae family. Native to Mexico and Central America, it has been introduced and is now naturalized in tropical parts of Asia and Africa. It is also naturalized in some Pacific islands, where it is found along roadsides and in disturbed areas. T. diversifolia tolerates heat and drought and can rapidly form large herbaceous shrubs. Rapid vegetative reproduction and significant production of lightweight seeds, which can be dormant in the soil for up to four months, allow T. diversifolia to quickly invade disturbed habitats. By forming dense stands it prevents the growth of young native plants. Depending on the area, T. diversifolia may be either annual or perennial. Being able to produce flowers and seeds throughout the year, coupled with the ability of seeds to be dispersed by wind, water and animals, makes it particularly easy for T. diversifolia to quickly colonize new areas. Shoot and root growth and nutrient uptake of several plants may be adversely affected by T. diversifolia.

Hosts

Imeokpara and Okusanya (1994) observed that most farmers found it difficult to manage T. diversifolia infestation in most crop fields, but particularly rice and maize fields. T. diversifolia has been reported to contain some allelochemicals and therefore may be capable of posing a serious phytotoxicity threat to agricultural crops. Goffin et al. (2002) isolated tagitinin C, a known sesquiterpene lactone (Pal et al., 1977;Baruah et al., 1994), from the aerial parts of T. diversifolia. According to Ayeni et al. (1997) several studies have indicated that these allelochemicals and their derivatives are toxic and may inhibit shoot and root growth and nutrient uptake of several plants. Ilori et al. (2007) similarly observed that the radical growth of Oryza sativa was inhibited by aqueous extract of T. diversifolia.


Source: cabi.org
Description

M. micrantha is a vigorous, fast-growing, perennial, creeping or twining plant with numerous cordate leaves and numerous large, loose heads of white or cream-coloured flowers that produce many seeds. This plant can climb and smother Hevea brasiliensis (rubber) trees as tall as 25 m.

Impact

M. micrantha is a fast growing vine, native to Central and South America. It was intentionally introduced into a number of countries and has since become a major weed in Southeast Asia and the Pacific and is still extending its range. However, it has not yet been recorded in Africa. Once established, M. micrantha can quickly smother other vegetation, including native trees, plantation species and agricultural crops, killing plants and/or decreasing yield and biodiversity. In Nepal, the vulnerable greater one-horned rhinoceros is under threat as M. micrantha outcompetes plant species on which it browses. Control of this species is difficult as it produces are large number of seed, can readily shoot from runners and suckers and can regenerate from stem fragments. This species has been the target of a biological programme in many countries.

Hosts

M. micrantha is a serious weed of agriculture, affecting over 20 species, including plantation trees such as species of Citrus, Theobroma cacao (cocoa), coffee (species of Coffea), Camellia sinensis (tea), Tectona grandis (teak), Hevea brasiliensis (rubber), Elaeis guineensis (African oil palm), Cocos nucifera (coconut) and Bambusa vulgaris (common bamboo). It is also a serious weed of species of Musa (bananas), Manihot esculenta (cassava), Zingiber officinale (ginger), Carica papaya (papaya), Ananas comosus (pineapple), Litchi chinensis (lychee), Saccharum officinarum (sugar cane), Ipomoea batatas (sweet potato), Colocasia esculenta (taro) and species of Dioscorea (yams), especially in warm, moist locations or where soil fertility is high (Cock, 1982;Waterhouse and Norris, 1987;Holm et al., 1991;Abraham et al., 2002a;Macanawai et al., 2010;Day et al., 2012a).


Source: cabi.org
Title: Arkoola nigra
Description

Surface hyphae dark-brown, septate, branched, shining, 14-20 µm broad, developing dark shiny appressoria at tips. Appressoria 250-300 µm, composed of several short branches. Intercellular hyphae pale-brown, branched, width varying. Ascomata pseudothecial, superficial or somewhat erumpent, black, setose, ostiolate, subglobose to obpyriform, uniloculate, 300-450 x 400-800 µ m. Wall 60-90 µ m thick, composed of four to six layers of oval to oblong cells, outer layers dark-brown to black. Setae septate, dark-brown, straight or flexuous, apex pale-brown. Asci cylindrical, short-stipitate, bitunicate, eight-spored, 230-300 x 24-30 µ m. Ascospores uniseriate, ellipsoidal to fusiform, pale-greenish, one-septate, 40-70 x 16-22 µ m, surrounded by a thin gelatinous sheath. Pseudoparaphyses hyaline, filiform, branched. In culture at 20°C, optimum for growth on potato dextrose agar, mycelium black with radiating hyphae and short aerial growth. For additional details, see Walker and Stovold (1986).

Recognition

Look for a web of dark mycelium with large branched appressoria on the surface of stems, leaves and fruits. Infected soyabean (Glycine max) seed is small and light in weight (Walker and Stovold, 1986).

Symptons

A. nigra produces an extensive, branching, dark-brown to black mycelium on the surface of soyabean (Glycine max) leaves, branches and pods. Circular to oval leaf spots, 1-10 mm in diameter, are grey to brown with a distinct thin, dark margin. Occurring on either side of the leaf, spots may coalesce and cause the leaf to tear easily, or a 'shot-hole' effect may appear when the centres of the spots fall out. If disease is severe, yellowing develops around and between the lesions. On pods and stems, the spots are oval-elongate and darker. Pods can be shrunken, containing discoloured seed below the lesion. Webs of dark mycelium can also appear on fallen parts and crop residue, as well as on the soil under and around them.
For additional details, see Walker and Stovold (1986) and Moore et al. (2006).

Impact

A. nigra is an ascomycete known only from certain parts of Australia. It was identified after causing substantial losses on soyabeans (Glycine max) as cultivation of that crop was expanded, but its pathogenicity was found to extend to other wild and cultivated legumes, some strictly Australian and others native or naturalized in many other parts of the world (Walker and Stovold, 1986). There was evidence that it could attack non-legumes as well. The fungus was observed to survive in and on soyabean crop debris, and was capable of infecting seeds, but its natural source and life cycle are unknown. Although the fungus is unlikely to be carried by any crop materials exported from Australia, the significant disease it can cause under humid conditions must make it a concern for accidental introduction to other regions.

Hosts

The fungus has only been observed on soyabeans (Glycine max) in the field, with the exception that one plant of Sida rhombifolia, a pan-tropic weed (USDA-ARS, 2009), was found to be infected (Walker and Stovold, 1986). Some of the other legumes (Fabaceae) in New South Wales, Australia were tested by inoculation. Most of these became infected, including both native and introduced species. Crotalaria pallida, an introduced forage legume, was heavily infected, as were the native species Kennedia rubicunda, Indigofera hirsuta and Vigna lanceolata (Walker and Stovold, 1986). The last two species have a pan-tropical distribution in the wild or under cultivation (USDA-ARS, 2009). Some native Glycine species were moderately affected (Walker and Stovold, 1986).


Source: cabi.org
Title: Arkoola nigra
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
Description


The colonies of C. formosanus contain three primary castes: the reproductives, soldiers, and workers. The majority of the nestmates are workers that are responsible for the acquisition of nutrients, i.e. cellulose in the wood. The head width of the white soft-bodied worker is approximately 1.2-1.3 mm and the body length is approximately 4-5 mm. The thorax is narrower than head width. The alates and soldiers are most useful for identification. The alates are yellowish-brown and 12-15 mm long. There are numerous small hairs on the wings of these comparatively large swarmers. The alates are attracted to lights, so they are usually found near windows, light fixtures, windowsills and spider webs, around well-lit areas. The soldiers are approximately the same size as the workers and have an orange-brown oval-shaped head, curved mandibles and a whitish body. When disturbed, the soldiers readily attack any approaching objects and may secrete a white gluey defensive secretion from the frontal gland. There are more soldiers (10-15%) in a C. formosanus colony than in a subterranean termite colony, such as Reticulitermes spp. (1-2%).

Recognition


Occasionally the foraging tubes may be observed on the wood surface or tree trunk. During the swarming season (April to June), elongated mud tubes that serve as flight exit slits may be seen. The damage by C. formosanus tends to occur in places with high moisture including the bathroom, kitchen sinks and leaky roofs. An acoustic emission device (AED) may be used to locate sites with feeding activity, but most AEDs have a limited detection range (Scheffrahn et al., 1993).

Symptons


Large colonies of C. formosanus generally live underground. When these termites invade a house aboveground, the foraging tubes of approximately 0.5-1 cm in diameter may be found connecting the soil and the infested house. In severe infestations, C. formosanus hollows out the wood leaving a paper-thin surface and the hollowed wood surface may look blistered or peeled. Another characteristic of C. formosanus is carton nest material that is made from termite faeces, chewed wood and soil. The honeycomb-like carton nests can be as large as 1-1.5 m in diameter and are usually found in structure-voids such as between walls and beneath sinks.

Impact

C. formosanus is often transported by boats and shipping containers to port cities before being carried further inland via landscape materials such as railroad ties (railway sleepers). This may explain the current C. formosanus distribution in the USA with coastal areas more densely infested than inland areas (Hochmair and Scheffrahn, 2010). Temperature and humidity are primary factors affecting the establishment of C. formosanus, and it is potentially invasive to areas of high humidity approximately 35° north and south of the equator (Su and Tamashiro, 1987). Competition from native species is another limiting factor for many exotic pests, but C. formosanus is more aggressive and is known to out-compete the endemic termites such as Reticulitermes species. Another factor that has allowed the successful establishment and spread of C. formosanus in exotic areas has been the pest control industry's heavy reliance on soil termiticide barriers for subterranean termite control since the 1950s. Numerous studies, using mark-recapture methods, have revealed that a single colony of C. formosanus might contain several million termites that forage up to 100 m in the soil (Lai, 1977;Su and Scheffrahn, 1988). These agree with the results of excavation studies for C. formosanus colonies (Ehrhorn, 1934;King and Spink, 1969). Because of the large colony size, the application of soil termiticides beneath a structure does not usually have a major impact on the overall population, and the surviving colony continues to produce alates that can further infest nearby areas. Once established, C. formosanus has never been completely eradicated from an area. The dependency of soil termiticide barriers as the primary tool for subterranean termite control is probably the main reason for the establishment and spread of C. formosanus from four isolated port cities in the 1960s in the USA to all south-eastern states by 2001.

Hosts

C. formosanus is an opportunistic feeder of any material containing cellulose. A large number of living plants are known to be attacked by C. formosanus, but it usually does not kill the plants unless the root system is significantly damaged (Lai et al., 1983;La Fage, 1987). Records show that living citrus, eucalyptus and sugar canes (Saccharum sp.) may be killed by C. formosanus, but in most cases damage occurs in the heartwood of a tree. The infested trees may be more easily blown over by high winds due to the loss of structural strength. The pest status of C. formosanus is most significant when it attacks wood products in a house such as structural lumbers, cabinets, etc. C. formosanus is also known to damage non-cellulose materials in search of food, including plastic, concrete and soft metal. Occasionally underground high-voltage power lines may be penetrated by C. formosanus, resulting in an area-wide power cut.


Source: cabi.org
Description

Adapted primarily from Keil and Ochsmann (2006) and DiTomaso and Healy (2007)

Impact

C. melitensis is native to northern Africa and southern Europe in the western Mediterranean region, and has successfully invaded similar climates in the USA, New Zealand, Australia and South America. In favourable habitats it can form dense stands that replace native and desirable vegetation. It is commonly less aggressive than Centaurea solstitialis and in some areas grows as a minor forb in annual grasslands. C. melitensis usually invades open, disturbed sites and is often spread by humans and livestock and by transportation of contaminated soil, crop seed or hay (DiTomaso and Healy, 2007).

Biological Control
A small beetle (Lasioderma haemorrhoidale) that feeds in the capitula of C. melitensis was unintentionally introduced in California from the Mediterranean region, but has had little impact on controlling C. melitensis populations (DiTomaso and Healy, 2007). It is a generalist seed feeder that also attacks C. solstitialis, C. sulphurea and Carduus pycnocephalus. Two other agents introduced for C. solstitialis, Chaetorellia succinea and Eustenopus villosus, also utilize C. melitensis, but to a lesser extent (DiTomaso and Healey, 2007). In host specificity tests, there was significant larval development by the Eurasian weevil Ceratapion basicorne on C. melitensis (Smith, 2007).

Source: cabi.org
Description

L. vulgare is a glabrous to sparsely pubescent shallow rooted perennial. Roots arise from a short creeping rootstock with many adventitious roots. Underground stems contain water soluble red pigments in the xylem and pith tissues and root tips may be red. Either short rhizomes or stout root-crowns may give rise to stems. Seedlings bear cotyledons that open above the soil surface;Stems are erect, simple or slightly branching, usually 1-2 per plant, but may form thick clusters. The stems are decumbent at their base, usually 30-90 cm in height reaching a maximum height of 2 m. Leaves are sparsely pubescent and three-nerved. Basal leaves are stalked, spatulate to obovate and irregularly dentate) to regularly crenulate 10-25 cm long and 3-7 cm wide. Stem leaves are smaller, alternate, mostly sessile, obovate to narrowly lanceolate becoming ligulate apically with coarse teeth and the base usually deeply lobed or fringed with slender segments. Flower heads are erect, usually solitary on long terminal peduncles and are 2.5-7.5 cm in diameter with 1-15 inflorescences per plant. The flower heads are mainly heterogamous with female ray florets and hermaphrodite disk florets. White ray florets, 15-30 per head are 0.5-2.4 cm long, ligulate, the apex rounded or with three small teeth;the 400-500 yellow disk florets are 4 mm long and tubular forming a dense, slightly domed centre. The numerous involucral bracts are green, edged with brown, and surround the base of each head. Fruits from both disk and ray florets are gray-silvery obovoid to cylindrical achenes with 5-10 equal raised ribs, 2-3 mm long and 0.8-1 mm wide. The pappus is absent or reduced to a crown. When crushed, all parts of the plant have a disagreeable sour odour (Clements et al., 2004).

Impact

L. vulgare is a perennial native to Europe and western Asia which has been introduced widely around the world. This species is reported as being invasive in the USA, Canada, India, New Zealand and Australia. In pastures and meadows it can form dense stands which can outcompete native flora and may reduce the diversity of natural vegetation or pasture quality. L. vulgare produces a large number of seed and can also regenerate from fragments of rhizome which makes control of this species difficult. L. vulgare may also serve as a host and reservoir for several species of polyphagous gall forming Meloidogyne nematodes. L. vulgare is federally regulated as a primary noxious weed in Canada.

Hosts


A range of crops may be invaded by L. vulgare including barley (Hordeum vulgare), flax (Linum usitatissimum), oats (Avena sativa), oilseed rape (Brassica napus), sunflower (Helianthus annuus), wheat (Triticum species) and Lucerne (Medicago sativa), but it is most commonly a problem in pastures. In natural grassland it may become dominant to the detriment of the natural vegetation, but no individual species have been reportedly threatened.

Biological Control
<br>Based on literature surveys eight European species have been prioritized as potential biological control agents based on records of their restricted host range. These include the root-mining tortricid moths Dichrorampha aeratana and D. baixerasana, the shoot-mining Dichrorampha consortana, the root-feeding weevils Cyphocleonus trisulcatus and Diplapion stolidum, the root-galling fly Oxyna nebulosa, the flowerhead-attacking tephritid fly Tephritis neesii and the flowerhead-attacking weevil Microplontus campestris (McClay et al., 2013). From 2010 onwards, host-specificity tests have been conducted to investigate the host range of these potential biological control agents. Tests with D. stolidum and C. trisulcatus revealed that these species are not specific enough to be considered further. In addition, tests with M. campestris revealed that this species has no evident impact on seed output. Host-specificity tests with D. aeratana and O. nebulosa are ongoing. and to date, none of these potential agents have been introduced to North America.

Source: cabi.org
Description

P. coronopus may behave as an annual, a biennial or a perennial. The plant can develop axillary offsets, hence reproducing vegetatively. A rosette of leaves develops, remaining flat or largely close to the soil. Leaves are up to 20 cm long by 2 cm wide, variously entire or shallowly or deeply toothed, somewhat pubescent. Under saline conditions the leaves may show distinct succulence. Flowering stems are numerous from each rosette, up to 20 cm high, carrying a dense spike of flowers 2-5 cm long. Each flower is subtended by a bract and consists of four sepals, the two on the posterior side conspicuously keeled and hairy. Alternating with the sepals are four whitish transparent petals. The flowers are normally hermaphrodite, having four stamens with long filaments, and large yellow versatile anthers and a syncarpous ovary surmounted by a long, hairy simple style. However, male sterility does occur. The capsule has two lower chambers with two seeds each, while there is usually an upper chamber containing a single smaller seed. The larger seeds are black, shiny, boat-shaped and 1.0-1.5 mm long (mean weight 0.20 mg) while the smaller are 0.7-0.9 mm long (mean weight 0.13 mg). The larger seeds are released when the capsule dehisces, while the smaller seed is usually retained (Rowling, 1933).

Impact


In its native range of Europe, northern Africa and Central and West Asia, P. coronopus is an inoffensive low-growing herb in coastal saline situations. It is rarely a weed of crops though Holm et al. (1979) list it as a ‘common’ weed in Spain. In recent years, however, it has been recorded as invasive in Australia and in California, forming dense mats which displace native vegetation, including endangered species in California (Weber, 2003;United States Fish and Wildlife Service, 2008a, b). Furthermore, it is reported as a weed problem in non-tilled orchards, irrigated pastures, and alfalfa and clover fields in California.

Hosts


In California, USA, P. coronopus is a weed problem in non-tilled orchards, irrigated pastures, and alfalfa (Medicago sativa) and clover (Trifolium spp.) fields. It is also reported as a threat to two endangered plant species in California;Trifolium amoenum (US Fish and Wildlife Service, 2008a) and Astragalus robbinsii var. jesupii (US Fish and Wildlife Service, 2008b).


Source: cabi.org
Description


The following text is adapted from the Flora of China Editorial Committee (2015). P. arenastrum has procumbent or ascending stems, 15-30 cm tall, branched from base. Petiole is short, articulate at base. Leaf blade is elliptic or oblanceolate, 0.5-2 cm × 2-5 mm, both surfaces with conspicuous veins, base narrowly cuneate, margin entire, apex usually obtuse;ocrea white, 2-3 mm, membranous, 5-7 veined, lacerate. Flowers 3-5, grow in axillary fascicles;with narrowly ovate bracts and acute apex. Pedicel articulate at apex. Perianth is green, 5-cleft to 1/2, veined, margin white;tepals oblong. Stamens 8;filaments dilated at base. Styles 3, very short;stigmas capitate. Achenes (one-seeded fruit that does not open to release the seed) are included in persistent perianth, dark brown, opaque, narrowly ovoid, trigonous, rarely biconvex, 2-2.5 mm, densely minutely granular striate.

Impact

P. arenastrum is an annual species native to Eurasia. It is found in field and row crops, orchards, yards, gardens and turf. It readily invades areas compacted by trampling with foot traffic and is therefore frequently found along roadsides, sports fields, vacant lots, gravel parking areas and walkways. This species establishes a taproot, which allows it to survive periods of drought. As a result it can compete with agricultural crops for water and nutrients reducing yields. In California it is reported to have a negative impact on the threatened species Arenaria ursina [ Eremogone ursina ]. P. arenastrum is considered as an environmental weed in parts of Australia and an agricultural weed in cropping systems in Australia and Canada.

Hosts

Smith et al. (2008) note that P. arenastrum is troublesome in agricultural fields, in particular in alfalfa fields (Medicago sativa), where soil is compacted from wheel traffic.


Source: cabi.org
Description

Conidiomata pycnidial, subepidermal, erumpent, dark, thick-walled, flattened to globose, varying in size, often 100-300 µm diameter, with or without a beak;beak to 76 µm. Phialides hyaline, simple or branched, sometimes septate, 10-16 µm long, arising from the innermost layer of cells lining the cavity. Alpha conidia hyaline, aseptate, sub-cylindrical, 5-8 x 2-3 µm. Beta conidia filiform, curved, hyaline, septate, 18-32 x 0.5-2.0 µm, non-germinating. Hyphae hyaline, septate, 2.5-4.0 µm diameter (see Edgerton and Moreland, 1921;Sherf and MacNab, 1986;Singh, 1987).

Recognition

Infection is easily visible in the field on close examination of leaves, stems and fruits;characteristic conidiomata appear as black pinhead-sized structures, which are often concentrically arranged on fruits. Infected fruits are soft and mushy or mummified and black. Infection of seed may be confirmed using the methods described for Seed Health Tests in 'Seedborne Aspects'.

Symptons

The symptoms range from poor germination and seedling blight to fruit rot. Post-emergence damping-off of seedlings results from infection of the stem just above the soil surface. The symptoms on leaves are more prominent during the early stages of plant growth. At first the lesions are small, more or less circular, and buff to olive, later becoming cinnamon buff, with an irregular blackish margin (Pawar and Patel, 1957). Irregular spots result from coalescence. After transplanting, leaves coming into contact with the soil may become infected directly or develop leaf spot due to infection by conidia. Lesions on the petiole or the lower part of the midrib can result in death of the entire leaf. Affected leaves may drop prematurely, and the blighted areas become covered with numerous black pycnidia.
On stems and branches, elongated, blackish-brown lesions are formed, eventually containing pycnidia. The diseased plant bears smaller leaves and the axillary buds are often killed. When stem girdling occurs, the shoot above the infected area wilts and dries up and the plant may be toppled by the wind (Edgerton and Moreland, 1921;Pawar and Patel, 1957;Sherf and MacNab, 1986). Pycnidia develop readily in lesions on young stems, but rarely on older ones (Harter, 1914).
On the fruits the symptoms appear first as minute sunken greyish spots with a brownish halo, which later enlarge and coalesce, producing concentric rings of yellow and brown zones. These spots increase in size and form large rotten areas on which conidiomata often develop concentrically, covering most of the rotten fruit surface. Pycnidia on fruit are larger than those on stems and leaves (Harter, 1914). If the infection enters the fruits through the calyx, the whole fruit may become mummified due to dry rot (Pawar and Patel, 1957).
Rot may appear in fruit, in transit after harvest (Sherf and MacNab, 1986).

Impact

P. vexans is a pynicidial anamorph with a teleomorph in the genus Diaporthe. Easily seedborne and producing large numbers of conidia, it causes disease in Solanum melongena [aubergine/brinjal/eggplant], its only significant host. This ranges from poor seed germination and damping-off of seedlings, to leaf and stem lesions and to fruit rot, both in the field and after harvest. The fungus has been reported from widely distributed areas of most continents, but only a few of those are in Europe and Africa, even though the climates are favourable. Seed transmission may explain its broad historical distribution, but limitation of its host range to a non-staple vegetable crop can allow for its avoidance and eradication by cultural methods. As a result, perhaps, it does not appear often on lists of restricted pathogens, even though it may cause yield losses of more than 50%.

Hosts

P. vexans has been considered to be restricted to Solanum melongena [eggplant/aubergine] (Edgerton and Moreland, 1921;Pawar and Patel, 1957;Sherf and McNab, 1986), but there are reports of pathogenicity to Capsicum annuum (pepper) and Lycopersicon esculentum [ Solanum lycopersicum ] (tomato) (Sawada, 1959;Tai, 1979) as well as of isolation from Acacia arcuaefolia (Mathur, 1979), Prunus armeniaca (apricot) (Dal Bello and Sisterna, 2000;Cho and Shin, 2004), and seeds of Sorghum bicolor (Mathur, 1979) and interception on imported Capsicum frutescens (BPI, 2009 [1945]). In India, it has been reported to infect some wild Solanum species in inoculation trials (Datar and Ashtaputre, 1988), and Solanum incanum (Dubey et al., 1987). Edgerton and Moreland (1921), nevertheless, were unable to obtain infection of tomato, pepper, potato [ Solanum tuberosum ] or wild Solanum species, and Pawar and Patel (1957) report identical results for tomato, pepper and potato, as well as finding no infection of Solanum nigrum. Those reports did not specify the plant parts inoculated, but uninjured tomato and pepper fruits were found to be unaffected by the fungus in parallel trials with brinjal [ S. melongena ] in India (Chaudhary and Hasija, 1979). Both young and fruiting pepper and tomato plants sprayed with suspensions of conidia were not infected (Harter, 1914).


Source: cabi.org
Description


Hyphae with frequent nodules, up to 8 µm wide, hyphal swellings in clusters, typically spherical, average 42 µm diameter. Sporangiophores thin (3 µm wide), proliferating through the empty sporangium or occasionally branched. Sporangia broadly ellipsoid to ovoid, 57 x 33 µm (up to 100 x 40 µm), no papilla, slight apical thickening, not shed. Oogonia average 40 µm diameter, wall smooth, becoming yellowish with age. Antheridia amphigynous, 21-23 x 17 µm. A full description is given in Waterhouse & Waterston (1966).

Symptons

P. cinnamomi causes a rot of fine feeder roots, and root cankers in some species, leading to dieback and death of host plants. Other symptoms include wilt, stem cankers (with sudden death of tree), decline in yield, decreased fruit size, gum exudation, collar rot (if infected through grafts near soil level) and heart rot (e.g. pineapple). A symptomless invasion of the sapwood has been reported in some species (Davison, 2011).

Impact

P. cinnamomi is a soilborne pathogen that is now widely established in many parts of the world. Initial long-range spread is likely to have been on infected nursery plants (e.g., Kenerley and Bruck, 1983;Benson and Campbell, 1985;Davison et al., 2006), and still occurs in this way. Additional long-range spread is by movement of soil and gravel infested with chlamydospores (e.g., Batini, 1977;Colquhoun and Petersen, 1994). Short-range spread is also by zoospores in drainage, seepage and irrigation water (Kinal et al., 1993;MacDonald et al., 1994). It has a very wide host range (Zentmyer, 1980) so that, once introduced into an area, it can persist on the roots of many different plants without necessarily causing symptoms on the foliage. It is a major pathogen of horticultural crops, in forestry and in natural vegetation, especially in southern Australia (Natural Resource Management Western Australia, 2013 - see http://www.dieback.net.au/pages/1382/susceptible-species). It is regarded as a key threatening process in the Australian environment (Environment Protection and Biodiversity Conservation Act, 1999), affecting both plant communities by reducing diversity, and the animal communities that depend on them.

Hosts


The host range is very wide and P. cinnamomi is the most widely distributed species of Phytophthora. Zentmyer (1983) stated there were nearly 1000 host species but, as research continues, the Project Dieback website (Natural Resource Management Western Australia, 2013) reports that over 2000 native plants are susceptible to Phytophthora dieback in Western Australia. The principal food crop hosts are avocados (root rot) and pineapples (root and heart rot);it also attacks Castanea, Cinnamomum, conifers, Ericaceae (including Rhododendron), Eucalyptus, Fagus, Juglans, Quercus and many ornamental trees and shrubs. Its recorded host range includes most of the temperate fruit trees, but these are not important hosts in practice. The impact of infection on hosts varies from symptomless infection restricted to root tissue to complete invasion of the root and stem storage tissue causing plant death (Environment Australia, 2001).


Source: cabi.org
Description


Plants typically cespitose, occasionally stoloniferous or rhizomatous, especially when heavily grazed or under frequently mowed. Culms 20-80 cm long, stiffly erect;nodes glabrous or short hirsute. Leaves basal;ligules 0.5-1.5 mm;blades 5-25 cm long, 2.0-4.5 mm wide, flat to folded, glabrous or with long, scattered hairs at the base of the blade. Panicles 5-10 cm, fan-shaped, silvery reddish-purple;rachises 0.5-2 cm, typically with 2-8 branches;branches 3-9 cm, erect to somewhat spreading from the axillary pulvini, usually with only one rame;rame internodes with a central groove narrower than the margins, margins ciliate, with 1-3 mm hairs. Sessile spikelets 3.0-4.5 mm, narrowly ovate;lower glumes hirsute below with about 1 mm hairs, lacking a dorsal pit;awns 9-17 mm, twisted, geniculate;anthers 1-2 mm (Vega, 2000).

Impact

B. ischaemum is a warm seasoned perennial grass in the Poaceae family which is native to Europe, Asia and Africa. There are two varities of B. ischaemum, var. ischaemum and B. ischaemum var. songarica, which have different native ranges and have been introduced into different countries. This species was introduced into the North American Great Plains in the 1920s to tackle soil erosion and for forage production. This species has since been planted onto millions of hectares of marginal rangeland, roadsides and Conservation Reserve Program lands (Harmoney et al., 2004). B. ischaemum can readily escape original planting sites where it can invade native rangelands, with negative ecological and economic consequences such as the formation of monocultures and the loss of native biodiversity. This species is a particular problem in Texas where dense monocultures are displacing native grass species.


Source: cabi.org
Description


The following description is from Brooks and Clemants (2000): A rhizomatous, perennial herb (graminoid), typically growing in dense clumps 20 – 60 cm tall. Rhizomes 2--3 mm diam. Culms erect, 2--6 mm diam. Cataphylls 0 or 1--2, straw-colored, apex narrowly acute. Leaves: basal 1--3, cauline 2--6, straw-colored;auricles absent;blade 2--25 cm x 1.5--6 mm. Inflorescences panicles or racemes of 2--50 heads or heads solitary, 2--14 cm, erect or ascending branches;primary bract erect;heads 3--70-flowered, obovoid to globose, 7--11 mm diam. Flowers: tepals green to brown or reddish brown, lanceolate;outer tepals 2.7--3.6(--4) mm, apex acuminate;inner tepals 2.2--3(--3.5) mm, nearly equal, apex acuminate;stamens 3 or 6;anthers ½ to equal filament length. Capsules included to slightly exserted, chestnut to dark brown, 1-locular, oblong, 2.4--4.3 mm, apex obtuse proximal to beak. Seeds elliptic to obovate, 0.4--1 mm, occasionally tailed.

Recognition

J. ensifolius is a low-statured plant that would be difficult to detect remotely, although ditchlines and areas with wet soil and shallow standing water that can be identified from images should be targeted in surveys. It can be readily identified visually by its combination of flattened leaves and dark, globular seedheads. Similar species can be readily distinguished as described in the ‘Similarities to Other Species’ section.

Impact

Juncus ensifolius is a mostly pioneering or ruderal species of rush that readily establishes in disturbed wet soils, often from buried seeds. Within its native range in western North America it is widespread and infrequent to common, typically a minor, secondary or at most co-dominant species in natural wetlands. Limited reports suggest that it behaves similarly in east Asia (Tachibana et al., 2001), where it is also native. Although it is recognized as having “potential for weediness” (Marr and Trull, 2002), it is not generally viewed as an aggressive invader within its native range and is widely used in wetland restoration and as a landscape plant. There are no published studies documenting its rate of growth, spread or dispersal.

Hosts


There is no evidence that J. ensifolius currently causes significant economic damage to any crop plants, although it apparently occurs as a minor contaminant in grass seed mixes (Piirainen, 2004) or commercial peat (Kirschner, 2002). It is recorded as a competitor of seven endangered species in Hawaii – see the 'Host Plants/Plants Affected' and 'Threatened Species’ tables for more information.

Biological Control
<br>Although J. ensifolius has a number of natural enemies (see ‘Natural Enemies’ section), there are no reports of their use for biological control.

Source: cabi.org
Description

All adult female Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) have a waxy outer covering for the protection of themselves and their eggs (the scale) (Weissling et al. 1999). The scale of mature females of A. yasumatsui are: "white, 1.2-1.6mm long and highly variable in form. They tend to have a pyriform shape with the exuviae at one end, but are often irregularly circular, conforming with leaf veins, adjacent scales and other objects. The ventral scale is extremely thin to incomplete. The scale of the juvenile male is similar to those of other species of Diaspididae, being 0.5-0.6mm long, white and tricarinate, with exuviae at the cephalic end. Scales of males are nearly always more numerous than those of females" (Howard et al. 1999). Adult males are orange-brown, and are similar in appearance to tiny flying midges, with one pair of wings and well-developed legs and antennae (Heu et al. 2003). Adult females are also orange in colour (Weissling et al. 1999).

Impact

Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) or the Asian cycad scale, is highly damaging to cycads, which include horticulturally important and endangered plant species. The cycad scale is an unusually difficult scale insect to control, forming dense populations and spreading rapidly, with few natural enemies in most localities where it has been introduced. The scale has the potential to spread to new areas via plant movement in the horticulture trade.

Hosts

Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) is found on plants from the gymnosperm order Cycadales, which consists of three families - Cycadaceae (Cycas a genus that contains its preferred host species), Stangeriaceae (Stangeria) and Zamiaceae (8 genera). CAS has been recorded on plants of the following genera: Cycas, Stangeria, Dioon, Encephalartos, Ceratozamia, Macrozamia and Microcycas (Howard et al. 1999;J. Haynes, pers. comm.;W. Tang, pers. comm.). These plants represent a wide variety of geographic origin. At Montgomery Botanical Center in Miami, Florida, the heaviest infestations appeared to be on Cycas and Stangeria eriopus. The threatened king sago (see Cycas revoluta in IUCN Red List of Threatened Species) appears to be more susceptible to CAS than most other species (Heu et al. 2003). The cycad scale infests pinnae, rachides, strobili, stems and roots of these various species of cycads. It is primarily found on the underside of leaves (Howard et al. 1999). In containerised plants, CAS usually aggregates on primary roots (about 10mm in diameter), and singly or in groups of a few on secondary roots (about 2mm in diameter) near the container sides. In the field, CAS has been observed at different depths on primary (3cm in diameter) and secondary roots in groups of a few to several individuals from near the soil surface to a maximum depth of 60cm (Weissling et al. 1999).
The preferred host genus of CAS is Cycas, which is native to Asia, as is A. yasumatsui. This suggests that Cycas may be the original host (Howard et al. 1999). CAS has been identified mainly in the monsoon areas of southeast Asia, and has seldom been found on cycads in rainforest areas. This suggests that the ability of CAS to infest roots may be an adaptation to surviving brush fires, a common occurrence in these monsoon areas (Howard et al. 1999).
In South Africa, CAS has been recently reported from non-native and native cultivated cycad species (Nesamari et al., 2015).
Host Plants and Other Plants Affected
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Plant name|Family|Context
Ceratozamia|
Cycas|Cycadaceae
Cycas micronesica|Cycadaceae
Cycas revoluta (sago cycas)|Cycadaceae
Cycas rumphii|Cycadaceae
Cycas taitungensis|Cycadaceae
Cycas thouarsii|Cycadaceae
Dioon|Zamiaceae
Encephalartos|Zamiaceae
Encephalartos ferox|Zamiaceae
Encephalartos lebomboensis|Zamiaceae
Encephalartos longifolius|Zamiaceae
Encephalartos natalensis|Zamiaceae
Encephalartos paucidentatus|Zamiaceae
Encephalartos transvenosus|Zamiaceae
Encephalartos villosus|Zamiaceae
Macrozamia|
Microcycas|
Stangeria|
Stangeria eriopus|Stangeriaceae
List of Symptoms/Signs
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Sign|Life Stages|Type
Growing point / dieback
Leaves / abnormal colours
Leaves / external feeding
Leaves / yellowed or dead
Roots / external feeding
Seeds / external feeding
Stems / external feeding
Biology and Ecology
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Reproduction
Female Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) can begin laying eggs within 21-35 days of hatching in warmer weather (Hamon, 2000;in IFAS, 2005). Eggs hatch within 8-12 days and some individuals have been observed to develop to second instars within 16 days, and third instars in 28 days. Mature females lay 100 eggs (Howard et al. 1999).
Lifecycle stages
Generally, scale insects initially hatch into a “crawler” stage capable of movement. When they find a suitable spot on a plant, they will insert their stylet (straw-like mouthparts) into the plant and begin feeding. Shortly after this, they will begin to create a covering over themselves, and they stay this way until they die. (IFAS, 2005).
Male cycad scales emerge from their scale shortly before death and fly in search of females for mating before they die. Females remain attached to the plant until their death. (Haynes and Marler, 2005). Most female cycad scales do not live longer than 75 days (Howard et al. 1999).
Natural enemies
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Natural enemy|Type|Life stages|Specificity|References|Biological control in|Biological control on
Cybocephalus nipponicus| Predator
Means of Movement and Dispersal
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Introduction pathways to new locations
Host: Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) can be transported to new locations by the import of infested cycad plants. There is high potential for CAS to spread in this manner as one or more fecund females hidden in the cycad can easily escape detection (EPPO, 2005).
Nursery trade: Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) can be transported to new locations by the import of infested cycad plants. There is high potential for CAS to spread in this manner as one or more fecund females hidden in the cycad can easily escape detection (EPPO, 2005).
Local dispersal methods
Garden escape/garden waste: The crawler stage of Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) can be spread via garden waste or infected pruning equipment (Hodges et al. 2003).
Host (local):
On animals: Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) can spread by "hitchhiking" on people,animals, birds, large insects etc. when in the crawler stage (Heu et al. 2003).
On animals (local): Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) can be carried by the wind when in the crawler stage (Heu et al. 2003) infesting plants more than a mile away (Moore, 2005).
Pathway Causes
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Cause|Notes|Long Distance|Local|References
Hitchhiker|| Yes
Yes
Horticulture|| Yes
Yes
Nursery trade|| Yes
Yes
Pathway Vectors
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Vector|Notes|Long Distance|Local|References
Debris and waste associated with human activities|| Yes
Host and vector organisms|| Yes
Yes
Plants or parts of plants|| Yes
Yes
Wind|| Yes
Plant Trade
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Plant parts liable to carry the pest in trade/transport|Pest stages|Borne internally|Borne externally|Visibility of pest or symptoms
Leaves
adults;nymphs| Yes
Pest or symptoms usually visible to the naked eye
Roots
adults;nymphs| Yes
Pest or symptoms usually visible to the naked eye
Stems (above ground)/Shoots/Trunks/Branches
adults;nymphs| Yes
Pest or symptoms usually visible to the naked eye
Plant parts not known to carry the pest in trade/transport
Flowers/Inflorescences/Cones/Calyx
Impact Summary
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Category|Impact
Animal/plant collections
Negative
Environment (generally)
Negative
Native flora
Negative
Rare/protected species
Negative
Impact
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General Impacts Compiled by IUCN SSC Invasive Species Specialist Group (ISSG) Aulacaspis yasumatsui (cycad aulacaspis scale (CAS)) threatens both ornamental and wild cycad populations. It spreads rapidly and can cover a large cycad within a number of weeks (Haynes & Marler, 2005). It has been observed to kill 100% of a Cycas revoluta population in cultivation within one year of infestation (Howard et al. 1999).
CAS has the potential to disrupt the horticultural trade in cycads. Cycads are valuable ornamental plants worldwide and the scale detracts from the appearance of plants even after treatment as the dead scales do not readily drop off (Howard et al. 1999). CAS also threatens the survival of several rare and already endangered species conserved in botanical collections (Howard et al. 1999;J. Haynes, pers. comm).
CAS can be easily spread to new locations via the plant trade as one or more fecund females on the plant can easily evade detection. This could threaten native cycad populations in these new locations (Emshousen et al. 2004), as is occurring in Guam where CAS is killing off the native cycad (see Cycas micronesica in IUCN Red List of Threatened Species) at an alarming rate (Haynes & Marler, 2005). It is expected that CAS will spread to other islands in the Caribbean and Micronesia unless strict controls are put in place to restrict its spread via commercial cycads.
Indigenous cycads in the genus Cycas in Micronesia would be at risk should the spread of CAS be left unchecked in these regions (Muniappan, 2005;J. Haynes, pers. Comm). CAS has been reported in the Taitung Cycad Nature Reserve, Taiwan, home of the endemic prince sago (see Cycas taitungensis in IUCN Red List of Threatened Species). A recent survey conducted in the reserve by the Taiwan Forestry Research Institute found that 90% of prince sago were infected by CAS, mortality was, however, found to be less than 3%.
Threatened Species
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Threatened Species|Conservation Status|Where Threatened|Mechanism|References|Notes
Cycas micronesica|EN (IUCN red list: Endangered)| Guam|Herbivory/grazing/browsing| ISSG,
2011
Cycas revoluta (sago cycas)|LC (IUCN red list: Least concern)|Herbivory/grazing/browsing| ISSG,
2011
Cycas taitungensis|EN (IUCN red list: Endangered)| Taiwan|Herbivory/grazing/browsing| ISSG,
2011
Risk and Impact Factors
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Invasiveness
Invasive in its native range
Proved invasive outside its native range
Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
Has high reproductive potential
Impact outcomes
Host damage
Negatively impacts forestry
Threat to/ loss of endangered species
Threat to/ loss of native species
Negatively impacts animal/plant collections
Impact mechanisms
Herbivory/grazing/browsing
Likelihood of entry/control
Highly likely to be transported internationally accidentally
Difficult/costly to control
Similarities to Other Species/Conditions
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The scale of the female hibiscus snow scale (Pinnaspis strachani (Cooley)) resembles A. yasumatsui, but P. strachani is far less common on cycads in southern Florida (Howard et al. 1999).
In the field, female A. yasumatsui resemble the magnolia white scale (Pseudaulacaspis cockerelli (Comstock)), which is also common on cycads in Florida. The two can be distinguished under a 10X hand lens, with the scale removed, using three features: 1) the colour of the body of all stages and of the eggs of A. yasumatsui is orange, except recently molted individuals, which are yellow. The eggs and all stages of P. cockerelli are yellow. 2) A. yasumatsui has an expanded prosoma. 3) Scales of A. yasumatsui are usually more numerous on the lower surface of leaves, while those of P. cockerelli are more numerous on the upper surface (Howard et al. 1999).


Source: cabi.org
Description


Descriptions of L. trifolii refer to fresh materials. Dry specimens may be distorted due to the manner in which they have been preserved. Also, the age of the specimen, when killed, will have some effect on its preservation characteristics.
For accurate identification, examination of the leaf mine and all stages of development are crucial.
Egg
L. trifolii eggs are 0.2-0.3 mm x 0.1-0.15 mm, off white and slightly translucent.
Larva
This is a legless maggot with no separate head capsule, transparent when newly hatched but colouring up to a yellow-orange in later instars and is up to 3 mm long. L. trifolii larvae and puparia have a pair of posterior spiracles terminating in three cone-like appendages. Spencer (1973) describes distinguishing features of the larvae. Petitt (1990) describes a method of identifying the different instars of the larvae of L. sativae, which can be adapted for use with the other Liriomyza species, including L. trifolii.
Puparium
This is oval and slightly flattened ventrally, 1.3-2.3 x 0.5-0.75 mm with variable colour, pale yellow-orange, darkening to golden-brown. The puparium has posterior spiracles on a pronounced conical projection, each with three distinct bulbs, two of which are elongate. Pupariation occurs outside the leaf, in the soil beneath the plant.
Menken and Ulenberg (1986) describe a method of distinguishing L. trifolii from L. bryoniae, L. huidobrensis, and L. sativae using allozyme variation patterns as revealed by gel electrophoresis.
Adult
L. trifolii is very small: 1-1.3 mm body length, up to 1.7 mm in female with wings 1.3-1.7 mm. The mesonotum is grey-black with a yellow blotch at the hind-corners. The scutellum is bright yellow;the face, frons and third antennal segment are bright yellow. Male and female L. trifolii are generally similar in appearance.
L. trifolii are not very active fliers, and in crops showing active mining, the flies may be seen walking rapidly over the leaves with only short jerky flights to adjacent leaves.
Head
The frons, which projects very slightly above the eye, is just less than 1.5 times the width of the eye (viewed from above). There are two equal ors and two ori (the lower one weaker). Orbital setulae are sparse and reclinate. The jowls are deep (almost 0.33 times the height of the eye at the rear);the cheeks form a distinct ring below the eye. The third antennal segment is small, round and noticeably pubescent, but not excessively so (vte and vti are both on a yellow ground).
Mesonotum
Acrostical bristles occur irregularly in 3-4 rows at the front, reducing to two rows behind. There is a conspicuous yellow patch at each hind-corner. The pleura are yellow;the meso- and sterno-pleura have variable black markings.
Wing
Length 1.3 -1.7 mm, discal cell small. The last section is M(sub)3+4 from 3-4 times the length of the penultimate one.
Genitalia
The shape of the distiphallus is fairly distinctive but could be mis-identified for L. sativae. Identification using the male genitalia should only be undertaken by specialists.
Colour
The head (including the antenna and face) is bright yellow. The hind margin of the eye is largely yellow, vte and vti always on yellow ground.
The mesopleura is predominantly yellow, with a variable dark area, from a slim grey bar along the base to extensive darkening reaching higher up the front margin than the back margin. The sternopleura is largely filled by a black triangle, but always with bright yellow above.
The femora and coxa are bright yellow, with the tibia and tarsi darker;brownish-yellow on the fore-legs, brownish-black on the hind legs. The abdomen is largely black but the tergites are variably yellow, particularly at the sides. The squamae are yellowish, with a dark margin and fringe.
Although individual specimens may vary considerably in colour, the basic pattern is consistent.

Recognition

L. trifolii are small black and yellow flies which may be detected flying closely around host plants or moving erratically and rapidly upon the leaf surfaces. Inspection of the leaf surface will reveal punctures of the epidermis and the obvious greenish-white mines with linear grains of frass along their length. For accurate identification, examination of the leaf mine and all stages of development are crucial.
L. trifolii larvae will be found feeding at the end of the mine, or the mine will end with a small convex slit in the epidermis where the larva has left the mine to pupariate on the ground. Sometimes the puparium may be found adhering to the leaf surface, although in most cases the fully-fed larva will have found its way to the ground beneath the plant to pupariate. This is especially true in hot, dry conditions where the larva/puparia would quickly desiccate if exposed on the leaf surface. Empty puparial cases are split at the anterior end, but the head capsule is not usually separated from the rest of the case.
Mined leaves should be collected into polythene bags and transferred to a press as soon as possible. Leaves containing larvae intended for breeding should be collected into individual polythene bags, which on return to the laboratory should be slightly over-pressurized by blowing into them before sealing the end. Blowing up the bag by mouth and sealing it adds valuable carbon dioxide to the moist air mix. Constant attention is required to ensure that puparia are transferred to individual tubes until the fly emerges. If the plant material begins rotting, good material with feeding larvae must be removed to more sanitary conditions.
When puparia are observed they can be very carefully removed to tubes containing a layer of fine sand, or a small strip of blotting paper or filter paper. This should be kept damp (never wet) until the adult emerges.
On emergence, the fly should be kept for at least 24 hours to harden up. Do not allow condensation to come into contact with the fly, or it will stick to the water film and be damaged.
Field collection of the adult L. trifolii is done by netting. The use of sticky traps, especially yellow ones, placed near host plants is a very effective method of collection and estimation of infestation.
If the puparial stage is collected from the soil, care must be taken not to damage the puparial skin or death will almost certainly follow. The pupae should be stored in glass tubes on a layer of clean sand or, better still, thick filter paper. The tube must have high humidity, but be free of condensation.
When the fly emerges, it must be allowed to harden for 24 hours before killing for identification purposes. Ensure that the tube has no condensation present.
Newly emerged adult L. trifolii are generally softer than specimens aged for several days and may crinkle as drying proceeds, especially the head. The ptilinal sac may still protrude from the suture between the frons and face obliterating some important characteristics. Adults should be dried slowly in the dark in a sealed receptacle over blotting paper. If preserving wet is preferred, the live specimen should be dropped into 20-40% alcohol, and transferred to 70-90% alcohol after 2 days.

Symptons

L. trifolii feeding punctures appear as white speckles between 0.13 and 0.15 mm in diameter. Oviposition punctures are usually smaller (0.05 mm) and are more uniformly round.
L. trifolii leaf mines can vary in form with the host plant, but when adequate leaf area is available they are usually long, linear, narrow and not greatly widening towards the end. They are usually greenish white.
In very small leaves the limited area for feeding results in the formation of a secondary blotch at the end of the mine, before pupariation. In Kenya, Spencer (1985) notes the growth of many L. trifolii from mines which began with a conspicuous spiral. This is not a characteristic associated with L. trifolii on other continents.
The frass is distinctive in being deposited in black strips alternately at either side of the mine (like L. sativae), but becomes more granular towards the end of the mine (unlike L. sativae) (Spencer, 1973).
Fungal destruction of the leaf may also occur as a result of infection introduced by L. trifolii from other sources during breeding activity. Wilt may occur, especially in seedlings.

Hosts


The host range of L. trifolii includes over 400 species of plants in 28 families including both ornamental crops (Bogran, 2006) and vegetables (Cheri, 2012). The main host families and species include: Apiaceae (A. graveolens);Asteraceae (Aster spp., Chrysanthemum spp., Gerbera spp., Dahlia spp., Ixeris stolonifera, Lactuca sativa, Lactuca spp., Zinnia spp.);Brassicaceae (Brassica spp.);Caryophyllaceae (Gypsophila spp.);Chenopodiaceae (Spinacia oleracea, Beta vulgaris);Cucurbitaceae (Cucumis spp., Cucurbita spp.);Fabaceae (Glycine max, Medicago sativa, Phaseolus vulgaris, Pisum sativum, Pisum spp., Trifolium spp., Vicia faba);Liliaceae (A. cepa, Allium sativum) and Solanaceae (Capsicum annuum, Capsicum frutescens, Petunia spp., Solanum lycopersicum, Solanum spp.) (EFSA, 2012).
It is now considered to be the most important pest of cowpea (Vigna uniguilata), towel gourd (Luffa cylindrica), cucumber (Cucumis sativus) and many other vegetable crops in southern China (Gao, 2014). In Europe, L. trifolii is a major pest of lettuce, beans, cucumber and celery, Capsicum sp., carnations, clover, Gerbera sp., Gypsophila sp., lucerne, Senecio hybridus, potatoes and tomatoes (EFSA, 2012). It is now a major pest of the Compositae worldwide, particularly chrysanthemums (including Dendranthenum, the commercial 'Mum') in North America, Colombia, and elsewhere. It also causes severe damage to different open field crops, such as chili peppers in Mexico.


Source: cabi.org
Description


Females of Cactoblastis cactorum have a wingspan of 27-40mm, whilst male wingspan is slightly smaller (23-32mm). The adult is fawn with faint dark dots and lines on the wings. It normally rests with its wings wrapped around its body. The forewings are greyish brown but whiter toward the costal margin. Distinct black antemedial and subterminal lines are present. Hindwings are white, semihyaline at base, smoky brown on outer half with a dark line along the posterior margin. The average longevity of the adult is 9 days. The incubation period of eggs depends on temperature;the shortest time being 18 days. The eggs usually hatch in 23-28 days. Larvae are gregarious in nature, initially pinkish cream coloured, with black red dots on the back of each segment. Later instars become orange and the dots coalesce to become a dark band across each segment reaching up to 1.5cm. The pupa is enclosed in a fine white silk cocoon which consists of a loose outer covering and a more compact inner cocoon. Pupation sites are usually found among debris of rotting cladodes under stones, logs, bark and just beneath the surface of the soil. The average length of the pupal period is 21-28 days. (Jordan Golubov., pers. comm., 2005).

Impact

The prickly pear moth (Cactoblastis cactorum) is a moth that preys specifically on cactus species. It has been introduced in various locations around the globe to provide biological control of invasive cacti species and has proved itself as a successful biocontrol agent in Australia, South Africa and some Caribbean islands. However, from the Caribbean it spread into Florida and has attacked non-target cacti species. It is feared that it will cause large scale losses of native cacti diversity in North America and possibly have a large economic, social and ecological impact in Opuntia rich areas of southwestern USA and Mexico.


Source: cabi.org
Description

Adult
Specimens should be carefully examined for the wing pattern.
Diagnostic features of the genus are as follows (characters extracted from key to North American genera of Tephritidae by Foote et al., 1993): Head with two pairs orbital setae;posterior pair reclinate. Gena with only short anterior setae. First flagellomere (third antennal segment) at least slightly pointed at the apex. Thorax with dorsocentral setae closer to level of anterior supra-alar setae than transverse suture. Scutellum not swollen or shiny. Wing with cells bm and bcu of similar depth;bcu with a short acute extension. Crossvein R-M near middle of cell dm.
This species may be identified using the Diptera key in the Crop Protection Compendium taxonomic identification aid. For full details of its separation from other North American species, see Foote et al. (1993).
The main features of the R. cingulata species complex (which also includes R. indifferens) are as follows: thorax and abdomen predominantly black. Scutellum base black. Apical band of wing forked, or upper arm of fork separated by clear area, leaving isolated dark spot at wing-tip.
In general, R. cingulata and R. indifferens are most easily separated by their location, with R. cingulata being eastern North American and R. indifferens being western North American, but there is a slight overlap in the distributions (see Distribution Section). In general, R. cingulata differs from R. indifferens as follows: R. cingulata has fore coxa yellow, anterior apical crossband on wing often reduced to an isolated spot (the stipple in the drawing shows possible joined condition);R. indifferens has fore coxa shaded black on posterior surface, anterior apical crossband rarely reduced to an isolated spot. See also Carroll et al. (2002).
Larva
Diagnosis of genus by Elson-Harris (White and Elson-Harris, 1994): Antennal sensory organ with a short basal segment and cone-shaped distal segment;maxillary sensory organ flat, with well defined sensilla surrounded by small cuticular folds;stomal sensory organ rounded, with a peg-like sensilla;large, preoral teeth near base of stomal sensory organ;no preoral lobes;oral ridges in 5-13 short, unserrated rows;no accessory plates. Stout spinules forming discontinuous rows on almost all segments. Anterior spiracles with 7-35 stout tubules. Posterior spiracular slits 3-8 times as long as broad, with 3-16 short, branched spiracular hairs. Anal lobes large, protuberant with well defined tubercles and sensilla.
An updated description of the larva of this species can be found in Carroll et al. (2004). Any Rhagoletis larvae found in cherry and having the following feature is likely to be this species: at least 21 tubules in each anterior spiracle. See the key to larvae in White and Elson-Harris (1994), which used a combination of host and fragmentary morphological data.

Recognition


Traps have been developed which capture both sexes, based on visual, or visual plus odour, attraction. They are coated in sticky material and are usually either flat-surfaced and coloured fluorescent yellow to elicit a supernormal foliage response (see Reissig, 1976), or spherical and dark-coloured to represent a fruit (see Prokopy, 1977);traps which combine both foliage and fruit attraction can also be used. The odour comes from protein hydrolysate or other substances emitting ammonia, such as ammonium acetate. See Boller and Prokopy (1976), Economopoulos (1989) and Liburd et al. (2001) for a discussion of these traps and Pelz-Stelinski et al. (2006a) for positioning of the traps. Burditt (1988) has evaluated different traps for catching R. indifferens in British Columbia, Canada.

Symptons


Attacked fruit will be pitted by oviposition punctures, around which some discoloration usually occurs. Infested fruits appear normal until the maggot is nearly full-grown, at which time sunken spots appear. Maggots and their frass inside the cherry render the fruit unsalable. Infested fruits are more susceptible to fungi. The third larval instar forms one to three holes (about 1 mm in diameter) through the skin of the cherry, before it leaves it for pupation in the soil (Frick et al., 1954).

Impact

R. cingulata (listed on EPPO A2 list) is a severe pest of cherries. It is closely connected to its host plants Prunus avium, P. cerasi, P. serotina, P. mahaleb and P. emarginata. Prunus mahaleb is native in warm locations of Southern and Central Europe. It is used as rootstock for tart cherries and as ornamental plant. In Germany R. cingulata appears 3-4 weeks later than the native species R. cerasi, and due to this attacks late cherry varieties, mainly tart cherries, e.g. the economic important variety “Schattenmorellen”. This has been proven by fruit samples, from which pupae were obtained and in the following year R. cingulata adults emerged (species confirmed by Dr. Allen Norrbom, Systematic Entomology Laboratory, USDA). Infestation levels in tart cherries amounted to more than 20%.

Hosts

R. cingulata attacks cherries (Prunus species). It is a pest of P. cerasus and P. avium (Bush, 1966), and P. serotina is the main native host (Foote et al., 1993).


Source: cabi.org
Description

B. tournefortii is an erect annual herb that has stems that can be from 10 to 100 cm tall, and a well-developed sturdy taproot system. It has a good number of primary stems and a large number of secondary stems that can be as high as 40. The size of the herb can vary considerably depending on soil moisture (Pratap and Gupta, 2009). The lower stems are densely covered with stiff bristles (Graham et al., 2005).

Impact

B. tournefortii is a widespread species of mustard, commonly known as African mustard or Sahara mustard. Native to Africa, Asia and Europe, it has spread globally and naturalised in North America, Australia and New Zealand. It is a highly invasive annual herb and is recorded as negatively affecting native species in some US states and Australia. Its fast growth rates enable it to monopolize soil moisture and light and mature before native wildflowers. B. tournefortii is often the dominant species in areas of usually diverse flora. CalEPPC (1999) lists the species as ‘regionally most invasive wildland pest plant’. Some factors may increase its invasive capability, for example in the western Sonoran Desert of California, USA, B. tournefortii quickly invaded areas of natural disturbance where soils were young while older geological surfaces were less vulnerable to invasion. Another study in New South Wales, Australia, found that rabbit mounds enhanced the germination of B. tournefortii seeds.

Hosts


Australian Oilseeds Federation (2015) reported that B. tournefortii can contaminate canola oil crops, reducing yield through competition, and compromising oil quality.

Biological Control
<br>The use of biological control may not be suitable due to B. tournefortii being closely genetically related to a number of important agricultural crops such as broccoli (Brassica oleracea), canola (Brassica spp.) and cabbage (Brassica oleracea). Finding a bio-control that would not attack the cultivated species may be difficult (Holt and Barrows, 2014).

Source: cabi.org
Description

H. mantegazzianum is a monocarpic perennial herb, growing from a yellow, branched root system 40-60 cm deep and up to 15 cm across at the crown when mature. The root is somewhat contractile pulling the crown down to about 10 cm below the soil surface. While still vegetative, there is a rosette of leaves, increasing in size each year. These are alternate, the lowermost eventually up to 3 m long, to 1.7 m broad, ternately or pinnately lobed and coarsely toothed. Upper leaves on the flowering stem are progressively smaller. The upper leaf surface is glabrous but the underside and petiole are covered in bristles. When it finally flowers, usually after 3-5 years, there is a single hollow stem up to 2-5 m high and 10 cm in diameter. The stem is ridged, with purple blotches, and covered in pustulate bristles. The main inflorescence is a terminal compound umbel up to 80 cm across with about 100 unequal hairy rays, each 10-40 cm long. There are also up to eight satellite umbels which overtop the main one, and others developing on branches below. The main umbel is hermaphrodite;the lower ones, maturing earlier, may be only male. Flowers, on pedicels 10-20 mm long, are white or pinkish with petals up to 12 mm long. Numerous fruit flattened, elliptical, 6-18 mm long by 4-10 mm wide, narrowly winged, the larger fruits occurring on the main inflorescence and the smaller on satellites;glabrous to villous, splitting into two mericarps, each with 3-5 elongated oil ducts. For the first few years, the above-ground growth dies down each winter. Once it has flowered, the plant dies altogether (from Tiley et al., 1996.) Nielsen et al. (2005) have excellent line drawings of H. mantegazzianum and related species.

Hosts

H. mantegazzianum is not normally a weed of crops but there are reports of its encroachment into crop fields, such as potatoes in Sweden (Lundstrom, 1984). It has also been reported spreading into forest margins and sparse forest canopies (Thiele et al., 2007).


Source: cabi.org
Description

A. calendula is a rosette-forming perennial usually infesting disturbed, urban, and coastal habitats. It prefers a good amount of sun and sandy, well-drained soil. It can grow up to 25 centimeters tall (10 inches) and exhibits purple or yellow daisy-like flowers that can reach 6 centimeters (2.5 inches) in diameter. The plant is pollinated primarily by butterflies. A sterile, vegetatively reproducing yellow-flowered race is not currently regulated in California, but is noted by some to escape from cultivation. This form is now considered a separate species, A. prostrata, sometimes sold in the nursery trade. The invasive A. calendula is regulated in California has purple-tinged disc flowers, is seed-producing, and listed as a category A weed.


Source: cabi.org
Description

Atriplex hortensis is a hardy, annual plant, with an erect, branching stem, varying in height from 0.6 m to 1.8 m, according to the variety and soil. The leaves are smooth, heart- to shield-shaped, comparatively thin in texture, and slightly acidic to the taste. The flowers are small, momoecious, greenish or reddish, corresponding in a degree with the colour of the foliage of the plant;the seeds are small, black, and surrounded by a thin, pale-yellow membrane (Welbaum, 2015).


Source: cabi.org
Description

Infective CGMMV particles are rigid rods ca 300 x 18 nm with a helical structure of pitch 2.3 nm and a central canal of radius 2.0 nm. The central canal is usually clearly visible in the electron microscope in negatively stained preparations. The RNA lies at ca 4.0 nm radius from the centre of the core and the helix comprises 49 subunits/3 turns (Hollings et al., 1975).

Symptons

The virus becomes systemic in most infected plants reaching all plant parts, including roots and fruit, and remains able to infect other plants even when symptoms are absent.
In infected foliage and fruit, CGMMV symptoms vary between different cucurbit crop species and cultivars of the same species. In cucumber, green mottling occurs on young leaves and fruit surfaces, and infected plants may collapse. In watermelon, leaf mottling and mosaic develop in young plants, and their stems and peduncles develop brown necrotic lesions. Their foliage may develop a bleached appearance and wilt, and their runners, or even whole plants, may die prematurely. However, foliage symptoms sometimes fade in mature plants, especially in open-field situations. The fruits of infected plants often develop symptoms that render fruit unmarketable, including malformation and internal flesh symptoms of sponginess, rotting and yellowing or dirty red discoloration. In melon, young leaves develop initial mottle and mosaic symptoms that often disappear from mature foliage. Their fruits develop different degrees of malformation, mottling and surface netting. In pumpkin, squash, and zucchini, infected foliage is asymptomatic or leaf mottling and mosaic occur. Pumpkin fruits are always asymptomatic, but squash and zucchini fruits are sometimes externally symptomless and internally discoloured and necrotic. CGMMV symptoms are often indistinct in cucurbit seedlings, except when cotyledons turn yellow. In addition to causing marketable yield losses from poor fruit quality, CGMMV also causes gross yield losses, e.g. 15% and 50% in cucumber and watermelon respectively (Hollings et al., 1975;Dombrovsky et al., 2017 and references therein). Symptomless infection can also induce losses (Kooistra, 1968).
Different CGMMV strains differ in the symptoms they cause. For example, in cucumber, the type strain causes leaf mottling, blistering and distortion and stunted growth. Fruits are usually unmarked, but some strains cause severe fruit mottling and distortion. Some Asian cucumber cultivars show no leaf symptoms but they do suffer yield losses. The aucuba mosaic strain induces bright yellow leaf mottling in cucumbers, with only slight leaf distortion and stunting. Fruits may show yellow or silver-coloured streaks and flecks, especially at higher temperatures. In cucumber, symptoms appear 7-14 days after infection. At low temperatures, when the plants grow more slowly, leaf distortion is more severe (Smith, 1972).
In the field, the virus causes mosaic and occasionally wrinkling, green vein-banding and stunting of muskmelons. In the greenhouse it causes mild chlorosis, mosaic, vein-banding, and at the later stages deformed leaves with blisters (strain CGMMV-M) (Raychaudhuri and Varma, 1978). In Lagenaria siceraria the virus causes mosaic symptoms (VIDE, 1996). In Ecballium elaterium (Antignus, 1990) and other weed hosts (Shargil et al., 2017) the virus causes a symptomless infection.

Impact

CGMMV is a species of virus in the genus Tobamovirus, which was first described in 1935 in England. Between 1935 and 1985 it spread slowly to other countries, but faster between 1986 and 2006, and rapidly between 2007 and 2018. It now occurs on all continents except South America. In cucurbits, it causes a damaging disease that reduces fruit yields and quality and spreads efficiently by plant-to-plant contact transmission. Outbreaks occur in many cucurbit crops including vegetables and fruits (e.g. squash and melons). CGMMV seed transmission occurs in at least nine different cucurbit crop species and this is the main way the virus has spread worldwide. Importation of contaminated seeds constitutes a considerable biosecurity concern for counties still without CGMMV. Its high stability and its persistence in contaminated plant material and soil allow it to survive between growing seasons, making eradication difficult.

Hosts

The majority of plant species infected by CGMMV are in the family Cucurbitaceae. These include both major and minor vegetable and fruit cucurbit species such as rockmelon, cantaloupe and honeydew melon (Cucumis melo), cucumber (Cucumis sativus), watermelon (Citrullus lanatus), zucchini, squash and marrow (Cucurbita pepo), pumpkin (Cucurbita moschata and Cucurbita maxima) and several gourd species (e.g. Benincasa hispida, Lagenaria siceraria, Luffa acutangula, Momordica charantia), which are grown either as crops in their own right or as rootstocks for grafted watermelon (Dombrovsky et al., 2017 and references therein). At least 15 weed species from different continents have been identified as potential natural CGMMV hosts. These belong to nine different plant families (Dombrovsky et al., 2017 and references therein).
Several cucurbitaceous weeds likely act as reservoir hosts of the virus. Symptomless infection by CGMMV occurs in the weed squirting cucumber (Ecballium elaterium) in Israel, where it acts as an important alternative host of the virus (Antignus et al., 1990). Recently Shargil et al. (2017) reported that infected E. elaterium plants could transmit the virus to melon, cucumber and Nicotiana benthamiana via a bioassay. Horvath (1985b) found the same species to be susceptible following artificial mechanical inoculation, and also reported additional systemically infected cucurbit hosts including: Cyclanthera brachystachya, C. pedata, Melothria pendula (locally), M. scabra, Momordica balsamina, Sicyos angulatus (locally) and Zehneria japonica. Horvath (1985a) subsequently found two further systemically infected hosts, Lagenaria siceraria and Luffa aegyptiaca. However, as Horvath’s studies involved artificial inoculation they do not necessarily reflect true natural hosts. Sandeep and Joshi (1989) reported Momordica charantia as a natural host of the virus. Outside Cucurbitaceae, several natural hosts are known, however they are mostly weeds. For instance, Shargil et al. (2017) found additional asymptomatic hosts including: pigweed (Amaranthus graecizans), A. muricatus, dyer’s cotton (Chrozophora tinctoria), dwarf heliotrope (Moluccella laevis) and ashwagandha (Withania somnifera). Shargil et al. (2017) also demonstrated infection of the seed for pigweed and dwarf heliotrope. Prunus armeniaca was reported as a host of the virus (Cech et al., 1980), but this requires confirmation. Silverleaf nightshade (Solanum elaeagnifolium) and black nightshade (S. nigrum) were reported as hosts but this could not be confirmed. Hovárth (1986) reported systemic infection in Emex australis and E. spinosa following artificial inoculation.
For further information on the natural and experimental host ranges of CGMMV, see Hollings et al. (1975), Shargil et al. (2017) and Dombrovsky et al. (2017).


Source: cabi.org
Description

Densely caespitose perennial without rhizomes or stolons;culms up to 90 (100) cm tall, strongly compressed below, erect, unbranched, glabrous at the nodes, eglandular;basal leaf sheaths glabrous, chartaceous, strongly compressed, keeled and usually flabellate, eglandular, persistent;ligule a line of hairs;leaf laminas 10-80 cm x 1.5-4 mm, linear, flat or folded, glabrous, eglandular or with punctate glands along the midnerve. Panicle 10-35 cm long, narrowly oblong to narrowly ovate, the branches ascending or spreading, the spikelets appressed to the branchlets on pedicels 1.5-2 mm long, the primary branches not in whorls (but sometimes loosely clustered), terminating in a fertile spikelet, glabrous or thinly pilose in the axils, eglandular. Spikelets 6-13.5 x 0.5-2 mm, linear to narrowly oblong, laterally compressed, 9-13-flowered, the lemmas disarticulating from below upwards, the rhachilla persistent;glumes unequal, keeled, oblong-lanceolate in profile, scaberulous on the keel, acute at the apex, the inferior 0.5-0.8 mm long, reaching to about 1/3 the way along the adjacent lemma, the superior 0.9-1.5 mm long, shorter than the adjacent rhachilla internode or just exceeding the base of the adjacent lemma;lemmas 1.8-2.5 mm long, keeled, semi-ovate in profile (with straight or rarely concave keel and gibbous margins), membranous with prominent lateral nerves, appressed to the rhachilla, those in opposite rows not overlapping, the rhachilla visible between them, olive-green, glabrous but with punctate glands on the nerves, subacute at the apex;palea persistent, glabrous on the flanks, the keels slender, wingless and glabrous to scaberulous or slightly thickened with punctate glands;3 anthers, (0.9)1.6-2 mm long. Caryopsis (0.8)0.9-1.2 mm long, oblong to elliptic (Cope, 1999).

Impact

Eragrostis plana is a perennial grass native to southern African savannas. It is invasive in grassland ecosystems in southern Brazil, Uruguay and Argentina. In Rio Grande do Sul, Brazil, where it was accidentally introduced as a seed contaminant in the 1950s, it was then planted across the area as a forage alternative, but has since outcompeted native species in pastures and in native grasslands. The species is currently established on more than two million hectares of grasslands in southern Brazil. There, it flowers every three weeks in the warm months, tolerates frost and resprouts if mowed or grazed. E. plana thrives over compacted soil, being common on roadsides and parking lots, as well as in overgrazed areas. Seeds remain viable in the soil more than 24 years. It has proven a poor forage species and its invasion has resulted in economic losses to cattle ranchers.

Biological Control
No studies on biological control for this species are available, but Coelho (1993) recommends exploring this approach due to the difficulty of controlling the species chemically or mechanically.

Source: cabi.org
Description

The cultivated sunflower is an erect, hardy, often unbranched, coarse, stout-stemmed annual herb, with a varying height up to 4 m. The stem is robust, circular in section, 3-6 cm in diameter, curved below the head, and woody when mature. It is filled with white pith that often becomes hollow with age. The root is a taproot, which can penetrate the soil to a depth of about 3 m, with a large lateral spread of surface roots;however, most of the roots generally remain in the first 50 cm.

Impact

The following summary is from Witt and Luke (2017)


Source: cabi.org
Description

L. perenne does not produce stolons or rhizomes, its shoot buds arise at or near the soil level in young plants but may develop from higher nodes in large single plants. The nodal roots are variable, and may be white, thick, glossy, straight, unbranched and covered with root hairs or more slender and soon becoming fibrous (Beddows, 1967). The initial stem within the germinating seed is about 2 mm long and 2.8 mm in diameter and all the leaves, tillers and roots originate from this. Primary and adventitious roots arise from the base of the embryo (Soper and Mitchell, 1956). Beddows (1958) described L. perenne as a hemicryptophyte with a semi-rosette form before head emergence.

Impact

Lolium grasses have many weedy characteristics. They are capable of adapting rapidly to their environment, produce large amounts of seed, and are easily dispersed, usually by humans. The perennial ryegrass, L. perenne, is native to central Asia, the Middle East, North Africa and southern Europe, from Bulgaria in the east to France in the west. It was introduced by early European pastoralists to many corners of their earlier empires, including North America, Australasia, South Africa and elsewhere. As a result it has been sown in many countries and has become extremely widespread both as a cultivated species for livestock grazing and for fodder (as hay or silage). It is also a useful cover crop for soil stabilisation and pasture improvement, as well as an excellent grass for lawns and turf.

Hosts


The threatened spiny peppercress (Lepidium aschersonii) and the red darling pea (Swainsona plagiotropis) have both been reported as being threatened by L. perenne (University of Queensland, 2013).
A dense, uniform sward of L. perenne provides a very effective barrier to the germination and establishment of many common pasture weeds such as thistles (Popay and Medd, 1995).

Biological Control
L. perenne is ideally suited for biological control as there are a large number of insect pests and diseases that can damage or even kill the grass. However, being an extremely valuable and desirable pasture and turf species, biological control is unlikely to be used.

Source: cabi.org
Description

L. grandiflora is an emergent, aquatic, herbaceous perennial with two growth forms. During the first growth stage, the plant produces smooth or sparsely pubescent stems that grow horizontally over the soil or water, rooting at nodes and producing white, spongy roots. Leaves are smooth, alternate and have petioles. During the second stage, shoots begin to grow vertically and flower, stems become pubescent and can grow up to 1 m tall (USACE-ERDC, 2009). Leaves tend to be more elongate in the second growth form (IPAMS, 2009), but can vary widely in shape from lanceolate to elliptic and acute at both ends (USACE-ERDC, 2009). Flowers are on solitary stalks that are approximately 2.5 cm long;actinomorphic;sepals 5 (rarely 6), villous or glabrous;petals 5, caducous, obovate, emarginate, bright golden-yellow with a darker spot at the base;stamens in 2 whorls, the epipetalous ones shorter;disc slightly elevated, with a depressed, white-hairy nectary surrounding the base of each epipetalous stamen;style glabrous or hairy in lower two-third. Fruit is a pubescent light-brown capsule, 2.5 cm long containing 40-50 seeds, 1.5 mm long, embedded in a woody endocarp (IPAMS, 2009).

Impact

L. grandiflora is a productive emergent perennial native to South and Central America and parts of the USA. It was introduced to France in 1830 and has become one of the most damaging invasive plants in that country (Dandelot et al., 2008). It was more recently introduced beyond its native range in the USA, where it also causes severe problems (IPAMS, 2009). In its adventive range, L. grandiflora can transform ecosystems both physically and chemically. It can sometimes be found growing in impenetrable mats;under these conditions, L. grandiflora can displace native flora and interfere with flood control and drainage systems, clog waterways and impact navigation and recreation (IPAMS, 2009). The plant also has allelopathic activity that can lead to dissolved oxygen crashes and the accumulation of sulphide and phosphate in the water. These not insubstantial and year-round effects on water quality can cause ‘dystrophic crises’ and intoxicated ecosystems (Dandelot et al., 2005).

Hosts


Impacts on the local environment by L. grandiflora can be severe. The species possesses an allelopathic activity that changes water quality throughout the year and can lead to impoverished flora by decreasing seedling survival of vulnerable native taxa (Dandelot et al., 2008). L. grandiflora has been shown to cause severe hypoxia or even anoxia during summer months as well as leading to reduced sulphate and nitrate levels and increased sulphide and phosphate concentrations, leading to what Dandelot et al. (2005) refer to as ‘a dystrophic crisis’ and an intoxicated ecosystem.


Source: cabi.org
Description


The following is adapted from the description of Burkart (1976), the accepted monograph on the genus. P. velutina is a tree up to 15 m high with a short trunk, though it is often a low-growing, much-branched shrub where introduced. Spines are axillary, geminate, 1-2 cm long. All vegetative parts are more or less pubescent. Leaves bipinnate with 1-2 pairs of pinnae, sometimes 3, puberulous, to 6 cm long. Pinnae 2-9 cm long;leaflets oblong, pubescent, ciliolate, 12-30 per pinna, approximate, obtuse, nervate below, coriaceous, 4-13 mm long by 2-4 mm broad (approximately four times as long as broad). Racemes spike-like, 5-15 cm long, florets yellow, short-pedicelled, somewhat pubescent outside, especially on the calyx;petals 2.5 mm long, the tip villous within. The legume is linear, 8-16 cm long, by 6-10 mm broad, flattened, straight or falcate, margins shallowly undulate, the stipe 2-10 mm long, with 10-17 seeds per pod;seeds ovate, 5-7 mm long.

Impact

P. velutina has been widely introduced and planted as a fuel and fodder tree. The seed are spread widely by grazing animals either from established plantations or from single trees around houses or water-holes, and will persist for long periods in the seed bank. P. velutina has shown itself to be a very aggressive invader, especially in arid and semi-arid natural grasslands, both in the native range and where introduced. Invasion in the native range generally involves an increase in plant density rather than an increase in its range. P. velutina is a declared noxious weed in Australia and South Africa where hybrids with P. glandulosa are common, hybrids also occur in other southern African countries. The genus as a whole is regulated in several other countries. In terms of ecology, uses, management and control, P. glandulosa and P. velutina can be effectively treated together, as a species complex.

Hosts

P. velutina is generally a weed of grasslands, natural or managed, in its native range. It invades similar habitats where introduced. Being a nitrogen-fixing species, like other species of Prosopis, it has a competitive advantage where soil nitrogen levels are low, as in over-grazed grasslands.


Source: cabi.org
Description

R. fruticosus is a very prickly, scrambling, woody shrub with a perennial root system and biennial canes. It grows up to 2 m or more tall and is extremely variable in leaf shape and plant form. Stems are variable, semi-erect canes, which grow up to 8 or 10 m long. The canes may be green, purplish, or red and have generally backward pointing thorns, and are moderately hairy, round or angled, sometimes bearing small, stalked glands. They are arching, entangling, and woody. Stems can root at the tips to form new plants and new stems grow from the base each year. Roots are stout, branched, creeping underground, growing vertically to a maximum depth of 1.5 m depending on soil type, from a woody crown up to 20 cm in diameter. Secondary roots grow horizontally from the crown for 30-60 cm, and then grow down vertically. Many thin roots grow in all directions from the secondary roots (Weber, 1995;Bruzzese 1998;Roy et al. 1998;Anon, 2001). The alternate leaves are divided into 3 or 5 serrated, shortly stalked, oval leaflets, which are arranged palmately, coloured dark green on top and pale beneath. Some taxa have the underside of leaves covered in pale hairs. Stalks and mid-ribs are prickly. Flowers are white to pink, 2-3 cm in diameter, with five petals and numerous stamens, in many-flowered clusters. In the northern hemisphere, R. fruticosus flowers approximately from May to August, in the southern hemisphere from November to April. The fruit is an aggregated berry, 10-20 mm long, changing colour from green to red to black as it ripens, made up of approximately twenty to fifty single-seeded drupelets. Seeds are deeply and irregularly pitted, oval, coloured light to dark brown, and 2.6-3.7 mm long and 1.6-2.5 mm wide.

Impact

R. fruticosus is highly invasive in some areas, it competes aggressively with native species and can therefore exclude and replace native vegetation, it forms thickets rapidly with a dense canopy of shade and can threaten sensitive and fragile ecosystems. R. fruticosus is a regulated noxious weed in Australia, New Zealand and the USA. However, it is still a widely grown commercial fruit species and as such, further imports of plant material are likely.


Source: cabi.org
Description

S. richteri (Order: Hymenoptera, Family: Formicidae), is a social insect that lives in colonies, usually associated with a mound. Most individuals are sterile female workers that perform a variety of functions, including care of the queen and brood, foraging, defense and nest building. The worker caste is polymorphic, ranging from small (minor) through intermediate (media) to large (major) individuals. Additionally, immature stages (eggs, larvae and pupae, or brood), winged reproductives and at least one queen will be present.
Colonies take approximately 2 years to mature and, on average contain, 200,000-400,000 individuals. Mature S. richteri colonies produce conspicuous mounds similar to those of S. invicta, averaging 30-50 cm in height and width, but they may be larger, reaching 90 x 90 cm. In hot dry conditions of late summer, S. richteri mounds may flatten out or disappear as the colony moves entirely underground. Mound building activity is stimulated by rainfall (Rhoades and Davis, 1967), and outbreaks have been found to be correlated with heavy precipitation, due to the queen’s needs for moist soil to excavate a nest (Green, 1962;Lofgren et al., 1975). Foraging worker ants enter and exit the colony through tunnels radiating up to 5-10m away from the mound. Colonies extend into the ground below the mound as interconnecting galleries, as much as 30-40 cm below ground level. In the USA, S. richteri colonies are usually found in open areas associated with some type of disturbance, e.g., lawns, hayfields, pastures, roadsides and highway medians, athletics fields, school grounds, etc. In their native Argentina, ideal habitats for S. richteri include the Pampas grasslands, as well as pastures of varying water content and seasonally waterlogged grassland (Taber, 2000). The disturbance of mounds results in a rapid defensive response by the worker ants, which will climb vertical objects in large numbers to bite and sting.

Recognition


Methods for detection of S. richteri are the same as those for S. invicta (see datasheet on Solenopsis invicta).
Visual inspection
Soil that is associated with any articles of trade or shipping equipment from areas known to be infested with S. richteri should be carefully inspected for the presence of ants. This could include various types of produce, turf and other nursery materials, honey bee equipment, hay, etc.
Foraging surveys
Baits are commonly used to survey for foraging activities of fire ant workers. A variety of food materials can be used, including sugar water, hot dogs, cookies, tuna, moistened pet food, etc. Baits are placed on or in such containers as petri dishes, plastic vials or test tubes, cardboard or laminated paper squares, etc. Under optimum conditions, fire ant workers will quickly find the baits and recruit other workers to them via trail pheromones. Baiting may be used by researchers to study ant behaviour, document impact of fire ants on other ant species, determine effectiveness of different control methods, time control applications, etc.
Monitoring fire ant mounds
Estimating the density of fire ant mounds in a given area is an easy way to quantify populations and monitor changes in population size in response to suppression measures. In addition to numbers, mound sizes and brood presence/absence can be used to further assess populations (e.g., see USDA mound rating system, Harlan et al., 1981). Some limitations to these methods include disappearance of mound structure in hot, dry weather, making detection more difficult ease of missing small, young colonies, location of fire ant colonies in areas not associated with a mound or hard to observe (e.g., tree stumps, hay bales), etc. Changes in populations through the year with changes in season usually necessitate sampling more than once to obtain reasonably accurate information.

Symptons


Information on crop hosts and feeding by S. richteri is limited, although S. richteri is known as a potato pest in Brazil (Taber, 2000). It is reasonable to expect similarities to S. invicta. S. invicta is omnivorous and foraging fire ants may be found in or on plants when they are preying on phytophagous arthropods associated with those crops. Plant feeding appears to be aggravated by dry or drought conditions. On other plants, the ants seem attracted to oil-containing plant parts such as the embryo portion of maize and sorghum seeds. Foraging workers on plants can become a hazard to field workers and tall, hardened mounds harbouring ant colonies in certain crops such as hay pastures or soyabeans can interfere with mechanized cutting and harvesting operations.
Affected plant stages include flowering stage, fruiting stage, post-harvest, pre-emergence, seedling stage and vegetative growing stage.
There is little or no specific information available on symptoms occurring in crops as a result of S. richteri feeding. In S. invicta, the following types of damage may be observed:
Fruits/pods: internal feeding;external feeding.
Leaves: wilting.
Roots: internal feeding;external feeding.
Seeds: internal feeding;external feeding.
Vegetative organs: internal feeding;external feeding.
Whole plant: plant dead;dieback;uprooted or toppled;internal feeding;external feeding
Biology and Ecology
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Genetics
In all ants, sex is determined by fertilization;unfertilized eggs produce males and fertilized eggs become females. Males occur only in the reproductive form, while females may become sterile workers or fertile reproductives (incipient queens). Whether a female becomes a worker or reproductive depends on its feeding and chemical (juvenile hormone and pheromones) environment (Tschinkel, 2006).
Two social forms are recognized in fire ants: monogyne colonies have a single functional (reproductively-active) queen, while polygyne colonies have multiple functional queens, ranging from 2-20,000 (Taber, 2000). Worker ants in monogyne colonies display territorial behaviour toward neighbouring colonies, whereas polygyne colony worker ants do not. As a result, polygyne colonies may have several-fold the number of ant mounds in a given area, sometimes reaching densities of several hundred mounds per hectare, 2-4 times the densities seen in monogyne areas (Porter et al., 1991;Porter, 1992;Porter et al., 1992;Fritz and Vander Meer, 2003). Polygyne fire ants are thus considered a greater economic and environmental threat than the monogyne form, although not as widespread. Polygyny is widespread only in S. invicta in the USA.
Polygyny exists in S.richteri in South America and is widespread there (Calcaterra et al., 1999;Briano et al., 1995). Apparently, only the monogyne form exists in the USA, although polygyny has been discovered in S. richteri / S. invicta hybrid populations (Glancey et al., 1989).
In the USA, S. richteri and S. invicta hybridize, resulting in an intermediate form that can produce fertile offspring. Polygyny has been reported in hybrids, but does not seem to be widespread. Currently, a broad band of hybridization between S. richteri and S. invicta exists from the Mississippi River to Atlanta, Georgia, occupying approximately 130,000 km 2 (Shoemaker et al., 1994).
Reproductive Biology
The S. richteri life cycle is similar to that of S. invicta (Taber, 2000). Winged reproductives form mating swarms and mating occurs in the air, after which the queen lands and sheds her wings;males die soon after mating. Several hundred virgin males and females may leave a colony at any one time. Mating flights can occur year round, especially in the native range in South America, but in North America often occur between April and August, usually on a warm, sunny day following rain. Following wing removal, queens establish colonies and start laying eggs. S. richteri queens establish their nests within approximately 3 cm of the soil surface, which is shallower than for S. invicta queens (Lofgren et al., 1975);however, the vast majority of queens perish before they can establish nests.
Once established, a queen at peak productive capacity can lay half her own weight in eggs daily and may live several years, until sperm depletion (Tschinkel, 2006). Before development of her first brood, the queen does not feed and must rely on stored food in the digestive tract and breakdown of flight muscles for nutrition (Taber, 2000). The queen loses a substantial amount of weight during care for the first brood. Eggs hatch into larvae, which pass through four instars;last stage larvae become pupae, which transition into adults. Workers, whether minor, media or major, change behavioural roles with age, first acting as nurses for queen and brood, then reserves (nurse + food reception from foragers) and, finally foragers. A new colony can start producing winged reproductives within 6-8 months, with production of several thousand individuals per year. It takes approximately 2 years for a colony to reach full maturity.
Physiology and Phenology
S. richteri is an adaptable species in a variety of ways, which contributes to its success. It is primarily a creature of disturbed habitats, both natural and manmade, in both its adopted and native countries (Tschinkel, 2006). It can aggressively exploit such areas, which is even more evident in S. invicta, allowing it to colonize and exclude other species that are potential competitors. The good fortunes of imported fire ants are closely tied to human activities, especially since the arrival of Europeans in the New World and the accompanying huge areas of ecological disturbance that resulted (Tschinkel, 2006). Fire ants are perhaps best viewed as pioneer species, evolved to exploit relatively rare and short-lived habitat patches derived from disturbance. They evolved high reproductive output as a response to dealing with such rare and unpredictable optimum habitat;effective dispersal mechanisms were also required to exploit habitats unpredictable in space. Additional adaptations to such habitats include rapid colony growth and early reproduction over a long season. Thus, fire ants have successfully exploited the highly disturbed landscape of the southeastern USA (Tschinkel, 2006). S. richteri produces a glycerol-type antifreeze which enables it to withstand colder temperatures than S. invicta, increasing its potential to move into habitats outside the range of S. invicta. Hybrid vigor associated with the S. richteri / S. invicta hybrid may also increase ability to withstand low temperatures (Callcott et al., 2000). S. richteri can readily adjust to varying environmental conditions, within limits, for example, moving brood around in mounds or underground to areas of optimum temperature and humidity. Its generalist feeding habits are an obvious adaptive advantage, allowing it to exploit habitats more efficiently.
Nutrition
S. richteri’s colony populations, foraging behaviours, diets and feeding behaviours are similar to those of S. invicta, which has been studied much more intensively (Taber, 2000;Tschinkel, 2006). Ants communicate through vision (sight), vibration (sound), touch and chemicals (pheromones), including a queen pheromone that attracts workers and a trail pheromone associated with the worker ant stinger. Upon locating food resources, a pheromone trail is produced which directs other worker ants to the site. Fire ants are omnivorous, consuming primarily other arthropods and honeydew produced by aphids and related insects (primarily Order Hemiptera, Suborder Sternorrhynca), but also seeds and other plant parts like developing or ripening fruit, and dead plant and animal tissues (Vinson, 1997). Living prey may be subdued by stinging. Foraging ants may bring solid or liquid food back to the colony;however, only certain larvae can process solid foods. Workers store liquid food in their crops, from where it can be regurgitated for nest mates (trophallaxis) (Glancey et al., 1981). Optimum ambient foraging temperatures range between 70 and 85 ° F (Rhoades and Davis, 1967).
Associations S. richteri symbionts have been studied in both South America and the southern USA. Caterpillars of the metalmark butterfly (Hamearis epulus signatus) spend much of their lives inside S. richteri mounds in South America, leaving the nest at night to feed on a leguminous host plant. When caterpillars are in the ant nest, workers feed on their bodily secretions. Other associates found in nests in South America included millipedes, short-winged mold beetles, seed bugs, lace bugs, wingless phorid flies, and rove beetles (Taber, 2000). One darkling beetle species native to South America, where it inhabits nests, is also found in the southern USA, although it has not actually been found in fire ant nests there (Taber 2000,).
Latitude/Altitude Ranges
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Latitude North (°N)|Latitude South (°S)|Altitude Lower (m)|Altitude Upper (m)
36
42
0
0
Air Temperature
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Parameter
Lower limit
Upper limit
Mean annual temperature (ºC)
15.2
20.4
Mean minimum temperature of coldest month (ºC)
0.8
9.3
Rainfall
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Parameter|Lower limit|Upper limit|Description
Mean annual rainfall|1011|1680|mm;lower/upper limits
Natural enemies
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Natural enemy|Type|Life stages|Specificity|References|Biological control in|Biological control on
Beauveria bassiana| Pathogen
All Stages| not specific
Burenella dimorpha| Pathogen
Caenocholax fenyesi
Adults| not specific
Kneallhazia solenopsae| Pathogen
All Stages| to genus
Argentina
Neivamyrmex opacithorax| Predator
Pachydiplax longipennis| Predator
Pseudacteon
Adults| to genus
Argentine, Brazil, Uruguay, USA (introduced)
Pseudacteon tricuspis| Parasite
Pyemotes tritici| Predator
All Stages| not specific
Solenopsis daguerrei| Parasite
Adults
Solenopsis molesta| Predator
Steinernema| Pathogen
Larvae/Pupae| not specific
Stichotrema wigodzinsky| Parasite
Vairimorpha invictae| Pathogen
All Stages| to genus
Notes on Natural Enemies
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There is a great deal of information available on imported fire ant natural enemies, including S. richteri, due primarily to the potential for biological control in areas where fire ants are invasive. The socially parasitic fire ant, Solenopsis daguerrei, was first discovered in S. richteri mounds in South America (Santschi, 1930). Colony parasitization rates in a given area can be as high as 31% and mound densities in affected areas are lower than densities where the parasite is not found (Calcaterra etal., 1999). Phorid flies in the genus Pseudacteon and several related genera produce larvae that decapitate worker ants and pupate inside their empty heads (Porter, 1998). Each species of fly parasitizes a characteristic size range of ants (Morrison et al., 1997;Morrison and Gilbert, 1999). Species that attack fire ants appear to be specific to fire ants (Porter, 1998). In addition to mortality, phorids appear to affect fire ant worker behaviour in important ways. Once flies are recognized, most ant workers seek cover, others curl into a stereotypical c-shaped defensive posture, and yet others freeze their posture (Porter, 1998). These behaviours generally result in reduced foraging rates;the presence of a single fly can stop or greatly inhibit the foraging of hundreds of workers within 2-3 minutes (Feener and Brown, 1992;Orr et al., 1995;Porter et al., 1995). In Argentina, the presence of six phorid species that attack S. richteri reduced the number of ants at food resources in the field, as well as foraging activity in general (Folgarait and Gilbert, 1999).

Impact

S. richteri is native to southeastern Brazil, central Argentina and parts of Uruguay. After its accidental introduction into the USA around 1918, it expanded its range into much of the southeastern USA and became a ubiquitous presence in a variety of urban and agricultural settings, as well as an important economic and environmental pest. However, the red imported fire ant, S. invicta, after its introduction through Mobile around 1930, gradually took over most of the range of S. richteri, and now occupies around 1,100,000 km 2, primarily in the coastal plains from N. Carolina to Texas (Porter and Briano, 2000). Currently, S. richteri is restricted to approximately 30,000 km 2 in northwestern Alabama, northeastern Mississippi and in parts of southern Tennessee, including a relatively recent introduction into Memphis (Jones et al., 1997). A broad band of hybridization zone between S.richteri and S. invicta exists between the two populations, occupying around 130,000 km 2 (Shoemaker et al., 1994). Comprehensive reviews of imported fire ants can be found in Lofgren et al. (1975), Taber (2000) and Tschinkel (2006). S. richteri is apparently more cold-hardy than S. invicta and thus has some potential to expand farther north, including possibly the southern Great Plains of the USA, which are similar to the South American Pampas, to which S. richteri is native. However, given human control efforts combined with intrusions of S. invicta and the S.richteri / S. invicta hybrid, it does not seem likely S. richteri will expand its range significantly in the future in the USA (Taber, 2000).

Hosts


Neither S.richteri nor S. invicta are considered major pests of crops although S. invicta is documented to feed on several crops, at times causing minor damage. S. invicta is well known to feed, and S. richteri workers probably feed, on honeydew produced by certain sternorrhyncan hemiptera (e.g., aphids, scale insects, mealybugs, etc.). Since the ants may protect these insects, their numbers may increase on some horticultural crops, especially if their natural enemies are reduced by fire ants.


Source: cabi.org
Description

O. aurantiaca is an inconspicuous, perennial succulent shrublet which seldom exceeds 0.5 m in height in open pasture but can reach up to 2 m when supported in vegetation. Plants consist of one to 100 or more spiny, sausage-like, fleshy segments or joints (also known as cladodes). These are 50 to 200 mm long (but may be longer when growing under shade) and 10 to 30 mm wide. Young segments are bright green and flattened whereas older joints are often cylindrical with a corky surface. Segments covered by soil may lose thorns and resemble an underground tuber. If above-ground parts die, or are removed, plants may grow from these underground segments. Green segments take on the function of true leaves that are only present on newly formed segments and fall away within a few months. During periods of drought, or when exposed to direct sunlight, segments take on a more reddish to purplish colour. Joints are easily detached from the parent plant and in wet conditions quickly take root when in contact with the soil surface. Flowers are bright yellow (not orange as is suggested by the species name). Fruit are initially green but are red to purple and club-shaped with age. Each fruit may contain several sterile seeds. Fruit can also take root, in a similar way to segments, when falling to the ground. Reproduction of this cactus is entirely vegetative. Sharp spines arise in groups from areoles, which also contain minute thorns or glochids. Long spines have minute, backward-directed barbs at their extremities. These can hook onto passing objects, mainly animals, facilitating dispersal of isolated joints.

Impact

O. aurantiaca has shown itself to be a serious invasive weed on natural grasslands in Australia and South Africa for over a hundred years, reducing carrying capacity, injuring livestock and reducing the value of animal products. It was introduced as an ornamental species and spread rapidly via dispersal of vegetative parts. However, introduction of cochineal and the cactus moth as biological control have reduced populations in infested areas to scattered plants or patches which now have mostly only a nuisance value. Nonetheless, there is a risk of further introduction into new areas via the trade in ornamental succulents and/or its escape where already present.


Source: cabi.org
Description

L. salicaria is a perennial herb 30-200 cm tall with a persistent woody rootstock. In North America and exceptionally in the southern limits of its native range, taller plants (up to 350 cm) can be found. Stems are erect and quadrangular in section with evenly spaced nodes in opposite pairs or in whorls of three. Leaves are 3-10 cm long, sessile, lanceolate to ovate and arising from each node (Thompson et al., 1987;Mal et al., 1992). The stem can be without lateral branches but plants usually form branches in the mid to lower part of the stem (Hegi, 1925). The length and number of lateral branches is variable, depending upon environmental conditions, probably soil nutrient status. Leaves are glabrous to pubescent on the stem and branches, or sub-tomentose on the inflorescence. Inflorescences are purple, in a dense terminal spike up to 1m long. In the first year or under poor nutrient conditions, plants usually have one shoot only, which dies at the end of growing season. In older plants, herbaceous stalks with lateral branches, each with terminal spike of flowers, arise from the rootstock to make a wide-topped crown (Thompson et al., 1987). Fruits are oblong-ovoid capsules (3-4 mm long) with two valves. Seeds are very small (200-400 µm in size, 0.5-0.6 mg in mass), thin-walled with two cotyledons and no endosperm (Thompson et al., 1987). The species is heterostylous with three distinct arrangements of pistils and stamens. The flowers are categorized according to stylar morphs as short-, medium- and long-styled (Mal et al., 1992).

Impact

L. salicaria, an Old World native, is a highly invasive species of wetlands in North America, beginning to spread rapidly about 140 years after its accidental introduction around 1800. It is a very variable species with an ability to occupy numerous habitats and substrates with the exception of dry places. Its spread and persistence in ecosystems is supported by very high seed production, a vigorous and persistent root system and rapid growth. It is an invasive species and/or noxious weed in almost all states and provinces of Canada and the USA where it is a serious threat to many sensitive wetland ecosystems.

Hosts

As an exotic invasive species, L. salicaria is not generally a weed of agricultural land as it prefers moist to wet habitats, but it may occur at disturbed edges of crop fields in the vicinity of wetlands. The establishment of L. salicaria adjacent to stands of wild rice (Zizania aquatica) in northern California and Wisconsin, USA, means that it may be or become a pest of this crop (Thompson et al., 1987).


Source: cabi.org
Description


Eggs
Eggs are 1 mm long, reddish-orange and in rows of 2-16 on the underside of leaves.
Larvae
There are four larval instars, which can be distinguished by their head capsule width (Haye and Kenis, 2004). The last instar larva is 8-10 mm long and has a head capsule width of 1.3-1.5 mm. Larvae resemble slugs with swollen orange, yellowish or brownish bodies and black heads. The anus is situated on the dorsal area, so that the excreta accumulates above the larva, which carries a viscous fecal shield on its back that gives it a repulsive aspect (Fox-Wilson, 1943).
Pupae
Pupae are orange-red and found in a 'silken', white cocoon in the soil.
Adults
The adult is about 6-8 mm long. It is bright red, with the exception of the head, antennae, legs and underside of the body, which are black (Fox-Wilson, 1943).

Impact

L. lilii is a Eurasian chrysomelid beetle that was first found in Quebec, Canada, in 1943, from where it has spread to several Canadian Provinces, and Vermont and Maine in the USA. It was also reported in Boston, Massachusetts, in 1992, and it is now found in several New England States. It is also alien and invasive in the UK and, probably, in Northern Europe. The beetle most probably spreads with the sale and movement of potted lilies, flowering bulbs or cut flowers. In countries where it is invasive, it is a serious pest of cultivated lilies and fritillaries. Without control methods, leaves and flowers are totally defoliated by larvae. In North America, it also represents a threat to native lilies.

Hosts


Larvae develop on cultivated and wild lilies (Lilium spp.), Fritillaria spp., Cardiocrinum giganteum and Maianthemum canadense (Lesage, 1983;Livingston, 1996;Cox, 2001;Haye and Kenis, 2004;Ernst et al., 2007). Other host plants for larvae mentioned in the literature must be regarded as dubious and may result from misidentifications of adults or larvae. Adults will accept a wider range of food plants, especially in laboratory rearing (Livingston, 1996).


Source: cabi.org
Description

Perennial grass;cespitose. Culms 25-120 cm, wiry, erect to sprawling, unbranched. Leaves basal and cauline;sheaths usually longer than the internodes, glabrous;collars glabrous or strigillose;ligules less than 0.5 mm;blades 5-40 cm long, 1-2.5 mm wide, flat to folded, straight to lax at maturity, adaxial surfaces with scattered, 1.5-3 mm hairs near the ligule. Inflorescences paniculate, 15-40 cm long, (8)10-35(45) mm wide;rachis nodes glabrous or strigillose;primary branches 5-25 cm, remote, stiffly ascending to divaricate, with axillary pulvini, usually naked near the base;secondary branches and pedicels usually appressed. Spikelets usually congested. Glumes subequal, 9-15 mm, 1-veined, acuminate;calluses 1-1.2 mm;lemmas 9-15 mm long, smooth to tuberculate-scabrous, narrowing to slightly keeled, usually not twisted, 0.1-0.2 mm wide apices, junction with the awns not evident;awns unequal or almost equal, not disarticulating at maturity;central awns 8-25(30) mm, straight to arcuate at the base;lateral awns absent or to 0-23 mm;anthers 3, 1.2-2.4 mm. Caryopses 6-8 mm, light brownish (Allred, 2003).

Impact

Currently, A. ternipes is only listed as introduced and invasive in Cuba (Oviedo Prieto et al., 2012). However, because this species behaves as a weed in areas within its native distribution range, its occurrence is commonly associated with habitat and soil disturbances (Allred, 2003).


Source: cabi.org
Title: Arundo donax
Description

A. donax is a tall, erect, perennial cane- or reed-like grass. One of the largest herbaceous grasses, it can grow to 2-10 m tall. Its root structure is very strong, with the fleshy, almost bulbous, creeping rootstocks (rhizomes) forming compact bundles from which grow the fibrous roots, penetrating deep into the soil. The horizontal rhizomes give rise to many-stemmed, hollow, cane-like clumps allowing it to form large colonies many metres across. These tough, individual stems or culms are divided by partitions at the nodes like in bamboo, each node 12-30 cm in length and can reach diameters of 1-4 cm with walls 2-7 mm thick. They commonly branch during the second year of growth, rarely multiple, just single lateral branches from nodes. The outer tissue of the stem is of a silicaceous nature, hard and brittle with a smooth glossy surface that turns pale yellow when the culm is fully mature. The pale, blue-green leaves clasp the stem broadly with a heart-shaped, hairy-tufted base, 2-6 cm wide at the base and tapering to a fine tip, up to 70 cm or more in length. The leaves are arranged alternately throughout the culm and very distinctly two-ranked, in a single plane. The culms can remain green throughout the year but often fade with semi-dormancy during the winter or in droughts. The flowers are borne in large plume-like panicles, 30-65 cm, at the upper tips of stems between March and September and are closely packed in a cream to brown-coloured cluster. The spikelets, flowering units comprised of one or more florets enclosed by two bracts or glumes, are several flowered, approximately 12 mm long with florets becoming successively smaller. The segmented central axis of the spikelet, the rachilla, is glabrous and dis-articulates above the glumes and between the florets. The more or less unequal glumes are 3-nerved membranous, narrow, slender, pointed and as long as the spikelets. Lemmas, the larger, outer, bract which, along with the palea, serves to contain the florets held within, are thin, 3-nerved and covered with fine, soft hair. They are narrowed upwards with the nerves ending in slender teeth.

Impact

A. donax is an aggressive species with an ability to reproduce quickly, allowing it to out-compete native plant species, and has established itself as one of the primary threats to native riparian habitats in its introduced range, dramatically altering ecological and successional processes and altering habitats towards dense, monotypic stands up to 8 m tall. It is listed as one of the 100 world’s worst invasive alien species (ISSG, 2011). This species represent a serious concern in arid and semiarid habitats because it outcompete native vegetation in the access to soil-water. It uses more water than native plants, lowering groundwater tables. A. donax is highly flammable and can change fire regimes in invaded areas (USDA-ARS, 2014).

Hosts

A. donax is not usually a weed of crops, rather tending to out-compete and displace native vegetation in riparian habitats. However, it has been reported as invasive in pasture/cropland in South Africa, Tanzania, Egypt, Argentina, Uruguay, Chile, Puerto Rico, and the Dominican Republic (ISSG, 2007;Randall, 2012).


Source: cabi.org
Title: Arundo donax
From Wikipedia:

Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil, called the pedosphere, has four important functions:

  • as a medium for plant growth
  • as a means of water storage, supply and purification
  • as a modifier of Earth's atmosphere
  • as a habitat for organisms

All of these functions, in their turn, modify the soil and its properties.

Soil is also commonly referred to as earth or dirt; some scientific definitions distinguish dirt from soil by restricting the former term specifically to displaced soil.

The pedosphere interfaces with the lithosphere, the hydrosphere, the atmosphere, and the biosphere. The term pedolith, used commonly to refer to the soil, translates to ground stone in the sense "fundamental stone." Soil consists of a solid phase of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution). Accordingly, soil scientists can envisage soils as a three-state system of solids, liquids, and gases.

Soil is a product of several factors: the influence of climate, relief (elevation, orientation, and slope of terrain), organisms, and the soil's parent materials (original minerals) interacting over time. It continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion. Given its complexity and strong internal connectedness, soil ecologists regard soil as an ecosystem.

Most soils have a dry bulk density (density of soil taking into account voids when dry) between 1.1 and 1.6 g/cm3, while the soil particle density is much higher, in the range of 2.6 to 2.7 g/cm3. Little of the soil of planet Earth is older than the Pleistocene and none is older than the Cenozoic, although fossilized soils are preserved from as far back as the Archean.

Soil science has two basic branches of study: edaphology and pedology. Edaphology studies the influence of soils on living things. Pedology focuses on the formation, description (morphology), and classification of soils in their natural environment. In engineering terms, soil is included in the broader concept of regolith, which also includes other loose material that lies above the bedrock, as can be found on the Moon and on other celestial objects as well.