Northern root-knot nematode is a species of vegetable pathogens which produces tiny galls on around 550 crop and weed species. They invade root tissue after birth. Females are able to lay up to 1,000 eggs at a time in a large egg mass. By surviving harsh winters, they can survive in cold climates.
Root-knot nematodes are plant-parasitic nematodes from the genus Meloidogyne. They exist in soil in areas with hot climates or short winters. About 2000 plants worldwide are susceptible to infection by root-knot nematodes and they cause approximately 5% of global crop loss. Root-knot nematode larvae infect plant roots, causing the development of root-knot galls that drain the plant's photosynthate and nutrients. Infection of young plants may be lethal, while infection of mature plants causes decreased yield.
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.
Solanum bulbocastanum, the ornamental nightshade, is a plant in the family Solanaceae, native to Mexico and parts of the U.S. Southwest. It is closely related to the potato and, as it has evolved strong resistance to all known varieties of potato blight, has been used to genetically engineer resistance into the cultivated varieties of potatoes around the world. The use of genetic engineering is helpful, as efforts to hybridize by traditional methods have so far been unsuccessful, and the use of somatic hybridization to transfer genes is difficult. A resistance to the Columbia root-knot nematode Meloidogyne chitwoodi has been identified in S. bulbocastanum, which can be transferred to cultivated potato.
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.
Meloidogyne javanica is a species of plant-pathogenic nematodes. It is one of the tropical root-knot nematodes and a major agricultural pest in many countries. It has many hosts. Meloidogyne javanica reproduces by obligatory mitotic parthenogenesis (apomixis).
Pratylenchus penetrans is a species of nematode in the genus Pratylenchus, the lesion nematodes. It occurs in temperate regions worldwide, regions between the subtropics and the polar circles. It is an animal that inhabits the roots of a wide variety of plants and results in necrotic lesions on the roots. Symptoms of P. penetrans make it hard to distinguish from other plant pathogens; only an assay of soil can conclusively diagnose a nematode problem in the field. P. penetrans is physically very similar to other nematode species, but is characterized by its highly distinctive mouthpiece. P. penetrans uses its highly modified mouth organs to rupture the outer surface of subterranean plant root structures. It will then enter into the root interior and feed on the plant tissue inside. P. penetrans is considered to be a crop parasite and farmers will often treat their soil with various pesticides in an attempt to eliminate the damage caused by an infestation. In doing this, farmers will also eliminate many of the beneficial soil fauna, which will lead to an overall degradation of soil quality in the future. Alternative, more environmentally sustainable methods to control P. penetrans populations may be possible in certain regions.
Meloidogyne acronea, the African cotton root-knot nematode or African cotton root nematode, is a plant pathogenic nematode affecting pigeonpeas. It is also an invasive species. The roots and surrounding soils of cereals, grasses, and Gossypium spp. provide habitat for this organism. M. acronea was confirmed as a potentially problematic pest of cotton, Gossypium hirsutum cv. Makoka, which was proven through pot experiments.
Meloidogyne artiellia, the British root-knot nematode, is a plant pathogenic nematode, infecting barley and chickpea. It is also an invasive species.
Meloidogyne brevicauda is a plant-parasitic nematode. It is also called tea root-knot nematode, mature tea nematode or Indian root-knot nematode. It is a member of the root-knot nematodes, which was identified by C. A. Loos in 1953 in Sri Lanka.
Meloidogyne naasi, the barley root-knot nematode or cereal root-knot nematode, is a plant pathogenic nematode, and also an invasive species. The nematode occurs as the primary root-knot pathogen on golf courses and turf in the Northeast United States, although it is unclear as to whether the pathogen is native or introduced. In 2019 it was reported damaging cereal and grass crops in Northern Ireland.
Meloidogyne partityla is a plant pathogenic nematode infecting pecan. One of the first described cases of this nematode where noted in pecan trees in South Africa by Brito et al. (2013). It is thought to have been introduced into South Africa by pecan seedlings that came from the United States. Today, this nematode is seen infecting pecan trees in Arizona, Arkansas, Florida, Georgia, New Mexico, Oklahoma, and Texas. They not only infect pecans, but they also infect the California black walnut, English walnut, shagbark hickory, and laurel oak. The first report in the US, was reported in South Carolina in which it infected laurel oaks but later started infecting neighboring pecan trees in the shared orchards. The health of infested trees continue to decline every year.
Meloidogyne thamesi, the Thames' root-knot nematode, is a plant pathogenic nematode (roundworm) infecting tea.
There are many plant-parasitic species in the root-knot nematode genus (Meloidogyne) that attack coffee such as M. incognita, M. arenaria, M. exigua, M. javanica and M. coffeicola. Study has already shown interspecific variability coffee, in which show how this species can be adapting to new hosts and environments.
Meloidogyne enterolobii was originally described from a population collected from the pacara earpod tree in China in 1983. In 2001 it was reported for the first time in the continental USA in Florida. M. enterolobii is now considered one of the most important root-knot nematode species because of its ability of reproducing on root-knot nematode-resistant bell pepper and other economically important crops.
Purpureocillium lilacinum is a species of filamentous fungus in the family Ophiocordycipitaceae. It has been isolated from a wide range of habitats, including cultivated and uncultivated soils, forests, grassland, deserts, estuarine sediments and sewage sludge, and insects. It has also been found in nematode eggs, and occasionally from females of root-knot and cyst nematodes. In addition, it has frequently been detected in the rhizosphere of many crops. The species can grow at a wide range of temperatures – from 8 to 38 °C for a few isolates, with optimal growth in the range 26 to 30 °C. It also has a wide pH tolerance and can grow on a variety of substrates. P. lilacinum has shown promising results for use as a biocontrol agent to control the growth of destructive root-knot nematodes.
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.
Pasteuria is a genus of mycelial and endospore-forming, nonmotile gram-positive bacteria that are obligate parasites of some nematodes and crustaceans. The genus of Pasteuria was previously classified within the family Alicyclobacillaceae, but has since been moved to the family Pasteuriaceae.
Prof. Waceke Wanjohi is a professor at Kenyatta University who works in plant pathology, research, teaching, networking, and graduate education. She is the Deputy Vice Chancellor (Academic) at Kenyatta University. She was appointed to act as the Vice chancellor of the same university from July 2022. Dedicated to boosting Africa's competitiveness in the global arena by improving agricultural output in smallholder farming systems in Sub-Saharan Africa.
