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Herbicides against weeds in maize

Published at: plantwise.org

Prevention of phosphorus deficiency in maize

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Malawi, July 2018 Prevention of phosphorus deficiency in maize Recognize the problem Phosphorus is one of the most critical nutrients for maize production. Its deficiency results in reduced yields and is common in soils in many parts of Malawi. Symptoms of phosphorus deficiency are that young plants look dwarfed and thin with dark green leaves. Leaf margins, veins and stems show purple tints which may spread over the whole leaf blade. Phosphorus deficiency is also manifested by reddish discoloration at juvenile stages of growth....

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Prevention of potassium deficiency in maize

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Malawi, July 2018 Prevention of potassium deficiency in maize Recognize the problem Potassium is a vital nutrient for maize production second to nitrogen in terms of quantity of a maize plant’s needs. Its deficiency is first seen on young lower leaves which are green and turn to yellow and brown colour. This may progress to upper leaves. Curling leaves with inter-veinal scorching and necrosis. Cobs of plants which have been deficient of potassium are noticeably narrowed or peaks and the grains on the cobs will have been poorly filled...

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Control of maize smut by seed treatment

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Tithonia diversifolia

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Rwanda, February 2016 Tithonia diversifolia Recognize the problem Family: Asteraceae (daisy family) Common names: Mexican sunflower, shrub sunflower, tree marigold. French: Tournesol mexicain; Kinyarwanda: Icyicamahirwe; Chichewa: Deliya. Annual or perennial herbaceous broadleaved shrub, woody at the base [2–3 (–5) m high]; stems slightly ridged and hairy when young. Leaves: Greyish-green, finely hairy on underside giving a grey appearance; opposite or alternate along the stem; simple, 3–5 (–7) pointed lobes (6–33 cm long and 5–...

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Maize dryness testing before storage

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Zambia, July 2015 Maize dryness testing before storage Recognize the problem Post-harvest losses are a common problem in maize production. Some farmers are storing maize before the cobs and grains are dry enough. Then fungal diseases germinate on the grains and destroy them. Background Farmers must dry or wait for their maize grains to dry in order to avoid germination of fungal diseases in the storage period. Well dried grains have only about 12 to 15% moisture, a cob that has just been harvested can have up to 50% moisture. Well...

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Management of maize streak virus

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Ethiopia, August 2015 Management of maize streak virus Recognize the problem Maize streak virus is very common in Ethiopia and is found in almost all maize growing areas. It has been reported to cause disease incidences that vary from a few infected plants per field to total yield loss with 100% infection. Erratic epidemics have been occuring every 3-10 years. The main damage caused is to plants younger than six weeks old. On young plants, the top and bottom surfaces of leaves have yellowish and light green streaks while mature plants...

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Oil and ash to protect grain barns from termites

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Zambia, July 2015 Oil and ash to protect grain barns from termites Recognize the problem Termites (lumoma in Tonga) are ½ to 2 cm wingless insects and some are even bigger. They have big heads with pincer-like mouthparts and a big abdomen. Termites eat wooden structures so they can destroy grain barns. They are also pests of various crops at almost all growth stages. In the case of maize, termites are destructive when the crop has matured and stalks have dried up. Termites also destroy the maize in the barn. Termites eat tunnel-like...

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Managing stemborer using push pull

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Ethiopia, August 2014 Managing Stemborer Using Push Pull Recognize the problem Maize stem borer is a major pest of maize in Ethiopia that attacks maize from the seedling stage to maturity and can cause total yield loss if not managed, especially if planted late. The young stem borer larvae cause windowing on the leaves. They later cause drying of growing tips (dead hearts) and holes in stems and cobs. Frass can be seen in the tunnels and holes made by the stem borers. Once the larvae enter the stem it is too late to manage the pest...

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Intercropping against leaf spot in eggplants

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Tanzania, December 2014 Intercropping against leaf spot in eggplants Recognize the problem Leaf spot disease, called “Madoa ya Majani” in Swahili, is a fungal disease. At early infection, several small (less than ¼ cm) circular to oval chlorotic spots appear on the upper side of the leaves. As time goes on, spots grow up to 1 cm, become light brown, and visible on both sides of the leaves. Later they become greyish brown and continue to concentrate at the centre of the leaves. Background Leaves may become infected by the disease when...

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Grain storage in metal silos against insect pests

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Zambia, July 2014 Grain storage in metal silos against insect pests Recognize the problem Major storage pests include the common maize weevil (also called the greater grain weevil, Busumpe in Tonga language and Impese in Bemba language) and the larger grain borer (also called Chidonkola mapwe). These pests eat lots of cereal grains when they have been in storage for six months or longer. Some grains have feeding holes when examined. Where grain is stored in bags, a powder is seen outside the bags. When a hand is passed through the...

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Cropping cowpeas with maize to improve soils

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Zambia, July 2014 Cropping cowpeas with maize to improve soils Recognize the problem Nitrogen deficiency in the soil is a huge problem for most small scale farmers. A common symptom of nitrogen deficiency in maize is the yellowing of the lower leaves of plants across the field. Such yellowing starts at the tips and moves along the middle of the leaf. Many plant diseases can cause yellowing, but these usually start from the middle of the leaf and along the veins (streaks) or appear as scattered spots. Background To counter the...

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Soil conservation using a magoye ripper

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Zambia, July 2014 Soil conservation using a magoye ripper Recognize the problem Frequent turning of top soil under conventional farming has made the soil loose and therefore prone to erosion by wind and water. Soil erosion washes away the nutrients from the organic manure and fertilizer in the soil. This causes a plough pan that hinders plant growth, and the loss of moisture that would have been used by the plant. The plants growing on fields that have eroded are yellow, have stunted growth and in severe cases can produce little or...

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Avoiding cassava mosaic virus in your field

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Democratic Republic of the Congo, May 2014 Avoiding Cassava Mosaic Virus in your field Recognize the problem Cassava is a hugely important crop in central West Africa. Unfortunately, it is affected by some major diseases and pests. Cassava Mosaic Virus has spread to many parts of Africa and can reduce yields considerably. In the field, you can recognise the virus by its mosaic pattern on the leaves, as well as making the leaf deformed and with blisters. The roots are reduced in size as well. This virus is transmitted from one plant to...

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Control of stalk borer by cutting maize stalks

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Tanzania, October 2014 Control of stalk borer by cutting maize stalks Recognize the problem Stalk borers are pest insects and can cause maize yield losses of up to 30%. They are 0.5 to 2 cm long white-yellowish caterpillars that first feed on maize tips, and later in the maize cob and maize stalk. The damaged plant appears stunted with broken tips and slightly yellowed upper leaves. The plant cannot produce yield as the upper broken part dries. Background Stalk borer adults are moths that do not cause any damage. They lay eggs on the...

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Control vectors of maize lethal necrotic disease

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FACTSHEETS FOR FARMERS www.plantwise.orgCreated in Tanzania, October 2014 Control vectors of Maize Lethal Necrotic Disease Recognize the problem Maize Lethal Necrosis Disease (MLND) is a viral maize disease. Leaves of infected plants become yellow from the tip and margins to the centre. Older leaves (bottom of plant) remain green. Ears and leaves dry up and sometimes look like a mature plant. The whole plant dies and maize cobs remain without kernels. MLND symptoms can be confused with symptoms of nutrient deficiency but plants affected by MLND appear only in some areas and are...

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Cultural control of bean fly in cowpea and bean

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Managing maize storage weevils with Tephrosia

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FACTSHEETS FOR FARMERS www.plantwise.org Created in Zambia , August 2013 Managing maize storage weevils with Tephrosia Recognize the problem Maize weevils (known as Sumpwa sumpwa in Nyanja language) cause large losses in maize grains. Their larvae hatch from eggs laid on to grains by weevils. The larvae cause damage by boring into the grain, making holes and grinding it to a fine powder. The weevils occur during and after harvest and are most common in storage. The grinded powder and bored grains are not fit for human consumption. Maize weevils...

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Management of chilli thrips through establishment of sprinkler irrigation

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FACTSHEETS FOR FARMERS www.plantwise.org Created in Sri Lanka , October 2013 Management of chilli thrips using sprinkler irrigation Recognize the problem Thrips are acknowledged to be the most destructive pest in chilli cultivation. Although farmers may spray various chemicals to control the thrips, they often do not achieve a good result. Applying chemicals increases the cost of cultivation and may lead to environmental harm. Chilli is an important crop grown in Sri Lanka. It is cultivated extensively in the dry zone. However the chilli...

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Control of thrips on cowpea

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FACTSHEETS FOR FARMERS www.plantwise.org Created in Sierra Leone , September 2013 Control of thrips on cowpea Recognize the problem The cowpea flower thrips or African bean flower thrips are shiny, black, slender, small-winged insects that feed on flower buds and flowers. During the pre-flowering period, nymphs and adults may damage the terminal buds. However, the main damage is on the flower buds and flowers. Attacked flower buds become brown and eventually fall off, leaving behind dark red scars. Damaged flowers are distorted and malformed. They...

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Names

Zea mays in differrent languages.

Bhutta
Makai
Makka
Makki
Mbembe
Mhindi
Mnavu
Muhindi
Osuga
Rinagu
Zea curagua
Zea indentata
Zea indurata
Zea japonica
Zea mays subsp. mays
Zea mays var. saccharata
Zea saccharata
Zea mays L. ssp. mays
Zea curagua Molina
Zea indentata Sturtev.
Zea indurata Sturtev.
Zea japonica Van Houtte
Zea saccharata Sturtev.
Maidis stigmata
Ekidid (Karamojong)
Maize
Corn
Mais
Maiz
Milho
Yumi
Khao phoat
List of sweetcorn varieties
List of sweetcorn varieties

Q&A

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

P. hysterophorus is an erect, much-branched with vigorous growth habit, aromatic, annual (or a short-lived perennial), herbaceous plant with a deep taproot. The species reproduces by seed. In its neotropical range it grows to 30-90 cm in height (Lorenzi, 1982, Kissmann and Groth, 1992), but up to 1.5 m, or even 2.5 m, in exotic situations (Haseler, 1976, Navie et al., 1996). Shortly after germination the young plant forms a basal rosette of pale green, pubescent, strongly dissected, deeply lobed leaves, 8-20 cm in length and 4-8 cm in width. The rosette stage may persist for considerable periods during unfavourable conditions (such as water or cold stress). As the stem elongates, smaller, narrower and less dissected leaves are produced alternately on the pubescent, rigid, angular, longitudinally-grooved stem, which becomes woody with age. Both leaves and stems are covered with short, soft trichomes, of which four types have been recognized and are considered to be of taxonomic importance within the genus (Kohli and Rani, 1994).;Flower heads are both terminal and axillary, pedunculate and slightly hairy, being composed of many florets formed into small white capitula, 3-5 mm in diameter. Each head consists of five fertile ray florets (sometimes six, seven or eight) and about 40 male disc florets. The first capitulum forms in the terminal leaf axil, with subsequent capitula occurring progressively down the stem on lateral branches arising from the axils of the lower leaves. Thousands of inflorescences, forming in branched clusters, may be produced at the apex of the plant during the season. Seeds (achenes) are black, flattened, about 2 mm long, each with two thin, straw-coloured, spathulate appendages (sterile florets) at the apex which act as air sacs and aid dispersal.

Hosts

P. hysterophorus is known to reduce the yield of various crops and to compete with pasture species in various countries. However, the yield loss and specific effects on the crops have not been quantified in all countries (Rubaba et al., 2017).;In Australia, the main impact of P. hysterophorus has been in the pastoral region of Queensland, where it replaces forage plants, thereby reducing the carrying capacity for grazing animals (Haseler, 1976, Chippendale and Panetta, 1994). Serious encroachment and replacement of pasture grasses has also been reported in India (Jayachandra, 1971) and in Ethiopia (Tamado, 2001, Taye, 2002). The weed is also able to invade natural ecosystems, and has caused total habitat changes in native Australian grasslands and open woodlands (McFadyen, 1992).;In India, the yield losses are reported as up to 40% in several crops and a 90% reduction of forage production (Gnanavel, 2013). P. hysterophorus is now being reported from India as a serious problem in cotton, groundnuts, potatoes and sorghum, as well as in more traditional crops such as okra (Abelmoschus esculentus), brinjal (Solanum melongena), chickpea and sesame (Kohli and Rani, 1994), and is also proving to be problematic in a range of orchard crops, including vineyards, olives, cashew, coconut, guava, mango and papaya (Tripathi et al., 1991, Mahadevappa, 1997, Gnanavel, 2013).;Similar infestations of sugarcane and sunflower plantations have recently been noted in Australia (Parsons and Cuthbertson, 1992, Navie et al., 1996), whilst in Brazil and Kenya, the principal crop affected is coffee (Njoroge, 1989, Kissmann and Groth, 1992). In Ethiopia, parthenium weed was observed to grow in maize, sorghum, cotton, finger millet (Eleusine coracana), haricot bean (Phaseolus vulgaris), tef (Eragrostis tef), vegetables (potato, tomato, onion, carrot) and fruit orchards (citrus, mango, papaya and banana) (Taye, 2002). In Pakistan, the weed has been reported from number of crops, including wheat, rice, sugarcane, sorghum, maize, squash, gourd and water melon (Shabbir 2006, Shabbir et al. 2011, Anwar et al. 2012).;In Mexico, the species is reported as a weed in cotton, rice, sugarcane, Citrus spp, beans, safflower, sunflower, lentils, corn, mango, okra, bananas, tomato, grapes, alfalfa, chili peppers, luffa, marigolds and other vegetables and fruit orchards. It is also a weed in nurseries. In Argentina is reported as a weed of tobacco fields (CONABIO, 2018).;Gnanavel (2013) also reports the following detrimental effects of P. hysterophorus on crops: it inhibits nitrogen fixing bacteria in legumes, the vast quantity of pollen it produces (ca. 624 million/plants) inhibits fruit setting, it is an alternative host for viruses that cause diseases in crop plants, and it is an alternative host for mealy bugs.

Biological Control
The use of insect and fungal pathogens and the exploitation of allelopathic plants is considered by Kaur et al. (2014) as the most economical and practical way to manage the infestations of the species. Biological control has been, and continues to be, considered the best long-term or sustainable solution to the parthenium weed problem in Australia (Haseler, 1976, McFadyen, 1992) and because of the vast areas and the socio-economics involved, this approach has also been proposed for India (Singh, 1997). South Africa was the first country in Africa to implement a biological control program against the species in 2003 (Rubaba et al., 2017). Four host-specific biocontrol agents have been released sequentially since 2010 after evaluation of their suitability, with variable establishment and spread (Strathie et al., 2016).;The use of insects as biocontrol agents had been tried in various countries (Kaur et al., 2014). Searches for, and evaluation of, coevolved natural enemies have been conducted in the neotropics since 1977. So far, nine insect species and two fungal pathogens have been introduced into Australia as classical biological control agents (Julien, 1992, McClay et al., 1995, Navie et al., 1996, Dhileepan and McFadyen, 1997, Evans, 1997a). Callander and Dhileepan (2016) report that most of these agents have become established and have proven effective in central Queensland, but that the weed is now spreading further into southern Queensland where the biocontrol agents are not present. Several of the agents are therefore now being redistributed into south and southeast Queensland.;The rust fungus, Puccinia abrupta var. partheniicola, is a prominent natural enemy in the semi-arid uplands of Mexico (Evans, 1987a, b), but since its release in Queensland in 1992, climatic conditions have been largely unfavourable (Evans, 1997a, b). It was accidentally introduced into Kenya (Evans, 1987a) and Ethiopia in mid-altitudes (1400-2500 masl) with disease incidence up to 100% in some locations (Taye et al., 2002a). Screening of another rust species (Puccinia melampodii) from Mexico was carried out (Evans, 1997b, Seier et al., 1997) and released in Australia in the summer of 1999/2000 (PAG, 2000). This fungus was later renamed Puccinia xanthii Schwein. var. parthenii-hysterophorae Seier, H.C.Evans & ç.Romero (Seier et al., 2009). Retief et al. (2013) report on specificity testing carried out in quarantine facilities in South Africa, and conclude that the fungus is suitable for release as a biological control agent of P. hysterophorus in South Africa. The authors suggest that this species has more potential for biocontrol in South Africa than Puccinia abrupta, which may have little impact in the low-altitude, high-temperature areas of the country where the weed is spreading.;In India, the mycoherbicide potential of plurivorous fungal pathogens belonging to the genera Fusarium, Colletotrichum, Curvularia,Myrothecium and Sclerotium, has and is being evaluated (Mishra et al., 1995, Evans, 1997a). Parthenium phyllody disease caused by the phytoplasma of faba bean phyllody group (FBP) was reported to reduce seed production by 85% (Taye et al., 2002b) and is being evaluated for use as a biological control agent in Ethiopia. Kaur and Aggarwal (2017) have tested an Alternaria isolate found on the weed, and report that it is worth investigating as a mycoherbicide for control of parthenium. Metabolites of Alternaria japonica and filtrates of Alternaria macrospora have caused significant damage to Parthenium (Kaur et al., 2015, Javaid et al., 2017).;Among the established insect biocontrol agents, the leaf-feeding beetle, Zygogramma bicolorata, the stem-galling moth, Epiblema strenuana, the stem-boring beetle, Listronotus setosipennis, and the seed-feeding weevil, Smicronyx lutulentus, are proving to be the most successful when climatic factors are favourable (McFadyen, 1992, Dhileepan and McFadyen, 1997, Evans, 1997a). Some control of parthenium weed has also been achieved in India with Z. bicolorata (Jayanth and Visalakshy, 1994, Singh, 1997, Sarkate and Pawar, 2006), although there has been controversy concerning its taxonomy and host specificity (Jayanth et al., 1993, Singh, 1997). Shabbir et al. (2016) reported that Z. bicolorata was most effective when applied in higher densities and at early growth stages of the weed. The distribution of this leaf beetle in South Asia was investigated by Dhileepan and Senaratne (2009), when it was present in many states in India, and in the Punjab region of Pakistan. Shrestha et al. (2011) reported that Z. bicolorata arrived in the Kathmandu Valley of Nepal in August 2010, and that by September it had spread over half of the valley areas where P. hysterophorus was present, although damage to the weed was only appreciable at one site.;Z. bicolorata has been seen attacking sunflowers in India and the use of Epiblema strenuata has not been effective, as it was found affecting Guizotia abyssinica crops (Kaur et al., 2014). More recently, Z. bicolorata and L. setosipennis have been released in South Africa and S. lutulentus is being evaluated under quarantine. Before approval as a biocontrol agent in South Africa in 2013, extensive testing suggested that Z. bicolorata would not become a pest of sunflowers in the country (McConnachie, 2015).;The use of antagonistic, competitor plants, such as Cassia spp. and Tagetes spp., has been recommended to control and replace P. hysterophorus in India (Mahadevappa and Ramaiah, 1988, Evans, 1997a, Mahadevappa, 1997, Singh, 1997). In Australia, Bowen et al. (2007) tested a number of grass and legume species against the growth of parthenium weed plants and identified further species that could suppress weed growth. Recently, Khan et al. (2013) tested a number of native and introduced pasture species and identified several of them to be suppressive against parthenium weed in both glasshouse and field conditions. The sowing of selected pasture plants in infested areas can suppress the growth of parthenium weed by as much as 80% and also provide improved fodder for stock (Adkins et al., 2012). Shabbir et al. (2013) showed that the suppressive plants and biological control agents can act synergistically to significantly reduce both the biomass and seed production of parthenium weed under field conditions. The suppressive plants strategy is easy to apply, sustainable over time, profitable under a wide range of environmental conditions and promotes native plant biodiversity. Species reported as effectively outcompeting P. hysterophorus are Cassia sericea, C. tora, C. auriculata, Croton bonplandianum, Amaranthus spinosus, Tephrosia purpurea, Hyptis suaveolens, Sida spinosa, and Mirabilis jalapa. Extracts of Imperata cylindrica, Desmostachya bipinnata, Otcantium annulatum, Sorghum halepense Dicanthium annulatum, Cenchrus pennisetiformis, Azadirachta indica, Aegle marmelos and Eucalyptus tereticornis are reported as inhibiting the germination and/or growth of P. hysterophorus (Kaur et al., 2014).

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

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

Recognition

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

Impact

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

Hosts

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


Source: cabi.org
Description


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

Impact

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

Hosts

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


Source: cabi.org
Description

Herbaceous, twining or creeping vine, attaining 3 m or more in length. Stems cylindrical, usually reddish, with long, erect, yellowish, non-glandular hairs. Leaves alternate, 5-palmately compound;leaflets 4-14 x 2-6 cm, oblanceolate or elliptical, the apex and base acuminate, the margins entire and ciliate, hispidulous to glabrate on both surfaces. Flowers in dichasial cymes;peduncles shorter than the petioles, hairy;bracts deciduous;sepals subequal or unequal, 1.5-2 cm long, with long, yellowish hairs;corolla funnel-shaped, white, 2.5-3 cm x 4-4.5 cm;five stamens, white;stigma bilobed, white. Fruit capsular, 4-valvate, subglobose, 1-1.5 cm in diameter, light brown, glabrous, surrounded by the persistent sepals. Four seeds per fruit, obtusely triangular, 5-6 mm long, brown, glabrous (Acevedo-Rodríguez, 2005;Austin et al., 2012).

Recognition

M. aegyptia can be easily recognized in the field by the 5-digitate leaves with entire leaflets, and the long, erect hairs covering the stems and calyx.

Impact

Merremia aegyptia is an annual climbing herb that acts as a pioneer species in disturbed sites in tropical regions. It is considered a weed in most countries where it occurs and it has been included in the Global Compendium of Weeds as an agricultural and environmental weed (Randall, 2012). The species is native to tropical America and Africa and listed as invasive in Cuba, India, Australia and Hawaii.

Hosts

M. aegyptia is a relatively common weed in sugarcane (Brazil, Lesser Antilles, Reunion) and maize fields (Guatemala, Brazil, Nigeria), where it climbs up plants, bending and entangling their stems (Standley and Williams, 1970;Fournet and Hammerton, 1991;Lima e Silva et al., 2004;Valery, 2006;Chikoye et al., 2009;Correia et al., 2010;Correia, 2016). It has also been reported in cotton (Cardoso et al., 2010), banana (Isaac et al., 2009), rice (Ismaila et al., 2015), green pepper (Coelho et al., 2013), muskmelon (Teófilo et al., 2012), yam (Fournet and Hammerton, 1991) and coffee plantations (Gavilanes et al., 1988).


Source: cabi.org
Description

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

Impact

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

Hosts


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


Source: cabi.org
Description

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

Impact

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

Hosts

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


Source: cabi.org
Description

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

Impact

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

Hosts

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


Source: cabi.org
Description

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


Source: cabi.org
Description

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

Impact

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

Hosts

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


Source: cabi.org
Description


The following description is taken from Flora of China Editorial Committee (2015):
Annual grass, culms tufted, erect or geniculately ascending, slightly flattened, 15–100 cm tall. Basal leaf sheaths strongly keeled, glabrous;leaf blades flat or folded, 5–30 cm, 2–7 mm wide, glabrous, adaxial surface scabrous, apex acuminate;ligule 0.5–1 mm, glabrous or ciliate. Racemes digitate, 5–12, erect or slightly slanting, 2–10 cm, silky, pale brown or tinged pink or purple;rachis scabrous or hispid. Spikelets with 2 or 3 florets, 2-awned;lower glume 1.8–2.2 mm;upper glume 3–4 mm, acuminate;lemma of fertile floret obovate-lanceolate in side view, 2.8–3.5 mm, keel gibbous, conspicuously bearded on upper margins with a spreading tuft of 2.5–3.5 mm silky hairs, margins, keel and flanks silky-ciliate or glabrous;awn 5–15 mm;second floret sterile, oblong, glabrous, awn 4–10 mm;third floret occasionally present, reduced to a small clavate scale, awnless.

Impact

Chloris virgata is a widespread and very variable weedy annual grass (Flora of China Editorial Committee, 2015). This species is a particularly aggressive invader of bare areas and degraded or disturbed native vegetation, and it has the potential to out-compete native vegetation in these habitats (Smith, 2002;Oviedo Prieto et al., 2012;Weeds of Australia, 2015). This weedy grass spreads from cultivation, pastures, gardens, disturbed areas and roadsides to nearby disturbed forest, creeks and riversides, native grasslands and coastal habitats such as coastal forests and sand dunes (Weeds of Australia, 2015;FAO, 2015;PIER, 2015). It also grows as a weed in agricultural lands (Vibrans, 2009). Currently, this species is regarded as an invasive and environmental weed in northern Australia (i.e., Queensland and the Northern Territory;Weeds of Australia, 2015) and as an invasive grass in Cuba, Palau, New Caledonia, the Galapagos Islands, and Hawaii (Wagner et al., 1999;Charles Darwin Foundation, 2008;Oviedo Prieto et al., 2012;PIER, 2015).

Hosts

C. virgata is a common weed in alfalfa (Medicago sativa) fields of the southwestern USA (Barkworth, 2003) and maize and sorghum plantations in Mexico (Vibrans, 2009).


Source: cabi.org
Description

D. ferox is an annual herb growing 50-150 cm tall. Stems are hairless or sparsely hairy with short and soft hairs, frequently branched and often purplish towards the base. Leaf shapes range from broadly ovate to rounded-triangular, 8-14 cm long and 6-16 cm wide;leaf margins are irregularly serrated or sinuate (with deep wavy margins). Flowers are white, often tinged with violet, 4-6 cm long, with five lobes, each lobe ending in a point of 1-2 mm length. Anthers are 3-4 mm long. Fruits are ellipsoid capsules up to 4 cm long. Each capsule bears up to 60 stout spines, the upper ones being longer than the lower ones. Seeds are black or grey and 4-5 mm long (George, 1982).

Recognition

D. quercifolia can be distinguished from D. ferox by more purplish coloration in foliage;corolla and anthers, slightly downy versus glabrous;and spines somewhat less stout (Houmani et al., 1999).

Hosts

D. ferox is a weed in summer crops, including maize, soybean, peanuts, grain sorghum, potato, sunflower and Cucurbitaceae (Parsons and Cuthbertson, 2001;Torres et al., 2013a,b).


Source: cabi.org
Description


Tree to 10 or more metres high, the branchlets usually tomentose when young. Leaves moderately large, an average leaf about 20-foliolate;petiole short, pubescent, eglandular;rachis usually about 2 dm. long, eglandular and otherwise like the petiole;leaflets several to many pairs, lanceolate, 3-8 cm. long and usually about 2 cm. wide, acute apically, obtuse basally, pubescent below, especially along the veins, puberulent to subglabrous above and less dull than below, opposite on the rachis, with 10 or more pairs of prominent lateral veins;petiolules 2-3 mm. long, pubescent. Inflorescence of several terminal or subterminal several-flowered racemes;bracts lanceolate, a few mm. long, caducous. Flowers yellow;sepals 5, obovate-orbicular, markedly unequal, up to 1 cm. long and broad, glabrous to lightly puberulent;petals 5, mostly obovate, markedly unequal, up to 2.5 cm. long and 1.5 cm. broad, subglabrous, venose, short-clawed;stamens 10, 3-morphic;the 3 lowermost the largest, their anthers oblong, about 7 mm. long, short-rostrate apically and dehiscent by terminal pores, the loculi somewhat converging terminally;anthers of 4 median stamens 5-6 mm. long, similar to the 3 lowermost except the rostrum reflexed and the loculi divergent terminally;3 uppermost stamens markedly dissimilar, more or less rudimentary, the anthers distinctly bilobed, each lobe reniform and dehiscent the length of its outer margin;ovary linear, glabrous. Legume linear, turgid-quadrangular, up to 2 dm. long and 1 cm. wide, transversely multiseptate, tardily dehiscent along one margin (Missouri Botanical Garden, 2014).

Impact

S. spectabilis is a medium to large tree from tropical America, listed in the Global Compendium of Weeds as an ‘environmental weed’, ‘garden thug’, and ‘naturalised weed’ (Randall, 2012). The species is extremely fast-growing, flowers and sets seed profusely, and re-sprouts readily when cut (Mungatana and Ahimbisibwe, 2010). In Australia it is considered naturalized, has been recorded as a weed of the natural environment and an escape from cultivation, and is labelled an invasive species, indicating its high negative impact on the environment due to its ability to spread rapidly and often create monocultures (Randall, 2007). In Uganda, the species is considered an invasive alien species with high risk to the native flora (Mungatana and Ahimbisibwe, 2010). In Singapore S. spectabilis has been identified as a casual, spontaneous exotic species that survives outside cultivation but does not form self-replacing populations, and relies on repeated introductions or limited asexual reproduction for persistence (Chong et al., 2009). The species is a cultivation escape in Trinidad and Tobago (Irwin and Barneby, 1982) and is considered an invasive species in Cuba (Oviedo-Prieto et al., 2012).

Hosts


Agroforestry experiments in Kenya showed that while S. spectabilis is useful as hedges for cropping systems, if grown in semi-arid conditions S. spectabilis will out-compete crops for water uptake and suppress crop yields;in the cases recorded, grain yields of maize grown with S. spectabilis or Leucaena leucocephala were reduced by between 39% and 95% (Noordwijk et al., 2004).


Source: cabi.org