Meloidogyne incognita, also known as the "southern root-nematode" or "cotton root-knot nematode" is a plant-parasitic roundworm in the family Heteroderidae. This nematode is one of the four most common species worldwide and has numerous hosts. It typically incites large, usually irregular galls on roots as a result of parasitism.
The soybean cyst nematode (SCN), Heterodera glycines, is the most devastating pest to soybean crop yields in the U.S., targeting the roots of soybean and other legume plants. When infection is severe SCNs cause stunting, yellowing, impaired canopy development, and yield loss. The symptoms caused by SCNs can go easily unrecognized by farmers—in some cases there are no warning symptoms before a loss of 30% of the yield. Due to the slight stunting and yellowing, many farmers may mistake these symptoms as environmental problems when in fact they are SCNs. Another symptom of SCNs that may affect farmers' yields is stunted roots with fewer nitrogen-fixing nodules. Due to the fact that soybean cyst nematodes can only move a few centimeters in the soil by themselves, they mostly are spread via tillage or plant transplants. This area of infection will look patchy and nonuniform making diagnosis more difficult for farmers. They can be seen in the roots of summer soybean plants if the roots are taken out very carefully and gently washed with water. The egg masses should be seen as bright white or yellow "pearls" on the roots. The later the roots are pulled the harder it will be to diagnose due to the SCNs female dying and turning a much darker color, forming a "cyst". The best way to know if a field is infected by soybean cyst nematodes is to take a soil sample to a nematologist.
Rotylenchulus reniformis, the reniform nematode, is a species of parasitic nematode of plants with a worldwide distribution in the tropical and subtropical regions.
Meloidogyne arenaria is a species of plant pathogenic nematodes. This nematode is also known as the peanut root knot nematode. The word "Meloidogyne" is derived from two Greek words that mean "apple-shaped" and "female". The peanut root knot nematode, M. arenaria is one of the "major" Meloidogyne species because of its worldwide economic importance. M. arenaria is a predominant nematode species in the United States attacking peanut in Alabama, Florida, Georgia, and Texas. The most damaging nematode species for peanut in the USA is M. arenaria race 1 and losses can exceed 50% in severely infested fields. Among the several Meloidogyne species that have been characterized, M. arenaria is the most variable both morphologically and cytologically. In 1949, two races of this nematode had been identified, race 1 which reproduces on peanut and race 2 which cannot do so. However, in a recent study, three races were described. López-Pérez et al (2011) had also studied populations of M. arenaria race 2, which reproduces on tomato plants carrying the Mi gene and race 3, which reproduces on both resistant pepper and tomato.
Pratylenchus brachyurus is a plant parasitic nematode.
Pratylenchus zeae is a plant-pathogenic nematode found on potatoes, maize, cereal, tobacco, coffee, blackberry, and found most often on sugarcane.
Globodera pallida is a species of nematode in the family Heteroderidae. It is well known as a plant pathogen, especially of potatoes. It is "one of the most economically important plant parasitic nematodes," causing major crop losses, and is a model organism used to study the biology of cyst nematodes. Its common names include potato cyst nematode, white potato cyst nematode, pale potato cyst nematode, potato root eelworm, golden nematode, and pale cyst nematode.
Heterodera avenae, the cereal cyst nematode or European cyst nematode, is a plant pathogen and an obligate parasite of cereal crops including barley, oats, wheat and rye. Cereal crops infected with this nematode are more susceptible to infection by fungal diseases such as rhizoctonia root rot.
Heterodera carotae is a plant pathogenic nematode commonly known as the carrot root nematode or carrot cyst nematode. It is found in Europe, Cyprus and India and is considered an invasive species in the United States. It causes damage to carrot crops and is very specific in its choice of hosts, only infecting Daucus carota and Daucus pulcherrima.
Heterodera humuli is a plant pathogenic nematode, the hop cyst nematode. It is an obligate parasite and infests hop plants, Humulus lupulus.
Heterodera schachtii, the beet cyst eelworm or sugarbeet nematode, is a plant pathogenic nematode. It infects more than 200 different plants including economically important crops such as sugar beets, cabbage, broccoli, and radish. H. schachtii is found worldwide. Affected plants are marked by stunted growth, wilting, yellowing, decreased yields, and death. While there are many methods of control, crop rotation with non-susceptible plants is preferred.
Hirschmanniella oryzae, i.e. rice root nematode (RRN), is among the major pests of rice and is the most common plant-parasitic nematode found on irrigated rice. Recent modifications in cultivation practices have led to a substantial increase in rice production, which has been accompanied by heightened levels of RRN. The proportional increases in RRN with rice production can be explained by the nematode's impeccable adaptation towards constantly flooded conditions in which irrigated rice is often being grown.
Tylenchulus semipenetrans is a species of plant pathogenic nematodes and the causal agent of slow decline of citrus. T. semipenetrans is found in most citrus production areas and diverse soil textures worldwide. Their feeding strategy is semi-endoparasitic and has a very narrow host range among commonly grown crops. These nematodes are considered as major plant-parasitic nematode because they can cause 10-30% losses reported on citrus trees. They also parasitize other hosts such as olive, grape, persimmon and lilac. The citrus nematode was first discovered in California in 1913 by J.R. Hodges and was later described and named by Nathan Cobb that year.
Mesocriconema xenoplax is a species of plant parasitic nematodes. Nematodes of this particular species are collectively called ring nematodes.
Heterodera is a genus of nematodes in the family Heteroderidae. Members of the genus are obligate parasites and different species attack different crops, often causing great economic damage. The genus is unique among nematode genera because of the ability of the female to transform into a tough, brown, cyst which protects the eggs which have been formed within her body. The name heterodera "refers to the different 'skins' of female and cyst."
Rice cyst nematode is the common name for several species of invasive plant-pathogenic nematodes:
Heterodera medicaginis, the alfalfa cyst nematode, is a plant pathogenic nematode which is cited as an invasive species. It is closely allied to Heterodera daverti, H. glycines and H. sonchophila in the H. schachtii-group. The only known host plant of this obligate parasite is the important crop alfalfa or lucerne, Medicago sativa.
Globodera tabacum, commonly known as a tobacco cyst nematode, is a plant parasitic nematode that mainly infests the tobacco plant, but also plants in family Solanaceae.
Pratylenchus alleni is a migratory endoparasitic nematode, living inside of plant roots and feeding on parenchyma cells in the root cortex. P. alleni is an obligate biotroph, meaning it must have a living host in order to survive. Due to their incredibly broad host range, Pratylenchus species fall third in total economic impact, finishing just behind cyst nematodes and root knot nematodes (Meloidogyne). In Canada, it was isolated for the first time in 2011 in a soybean field.
Heterodera zeae, the corn cyst nematode (CCN), is a plant parasitic nematode that feeds on Zea mays (maize/corn). The CCN has a limited economic impact worldwide due to its high soil temperature requirements.
