Pratylenchus penetrans
| Pratylenchus penetrans | |
|---|---|
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Nematoda |
| Class: | Adenophorea |
| Subclass: | Diplogasteria |
| Order: | Tylenchida |
| Superfamily: | Tylenchoidea |
| Family: | Pratylenchidae |
| Subfamily: | Pratylenchinae |
| Genus: | Pratylenchus |
| Species: | P. penetrans |
| Binomial name | |
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Pratylenchus penetrans (Cobb, 1917) Filipjev and Schuurmans Stekhoven, 1941 |
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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.
Root lesion nematode has a wide host range, including hosts like apple, cherry, conifers, roses, tomato, potato, corn, onion and sugarbeets, and ornamentals such as Narcissus. More than 164 hosts for P. penetrans have been recorded. In the host range there are some hosts that are susceptible, wheat, oat, field pea, faba bean, and chickpea, and some that are moderately susceptible, barley and canola.
Some general symptoms that are produced on infected plants include poor growth and chlorotic foliage. These secondary symptoms are often due to plant root stress. These make it rather difficult to diagnose nematode diseases in general. The roots when infected produce necrotic lesions, which are darkened areas of dead tissue, on the surface and throughout the cortex of the infected roots. These lesions turn the root to reddish-brown to black and are initially spotty. As the nematode continues to feed, the lesions can coalesce to become large necrotic areas of tissue that may eventually girdle the root. The population size of the nematode affects the degree of symptoms. Low to moderate populations may cause no visible above ground symptoms, while high populations can lead to stunting, nutrient and water deficiencies, and eventual die-back of the plant. On potato, infection of root lesion nematode can cause a secondary invasion by Verticillium dahliae leading to Potato Early Dying. Onions are another important host of P. penetrans. Onions are an important vegetable for consumption in the United States and upon infection the nematodes can limit yield and quality of the bulbs. Populations of more than 0.01 nematodes per cubic centimeter of soil resulted in injury to onions. There is a negative relationship between the increasing inoculum levels on onion root and top fresh weight at harvest.
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Wikipedia