Root-lesion nematode of wheat
Root-lesion nematode (Pratylenchus spp.) is found in most wheat production areas in the U.S. and Canada. It has a wide host range and can be very destructive in wheat. Symptoms include chlorosis of lower leaves, stunting, fewer tillers, and delayed plant growth. The root mass is reduced as nematodes degrade roots and reduce branching. Roots tend to turn brown, and other root rot pathogens may take advantage of wounds caused by root-lesion nematodes. Because root-lesion nematodes enter root tissue and disrupt the normal uptake of water and nutrients, drought or nutrient stress may be evident with high nematode levels.
Greater crop damage occurs in low-rainfall areas where cereals are grown continuously or in wheat-fallow rotations. Populations can build on susceptible wheat varieties, weedy hosts, and volunteer cereals.
A few root-lesion nematode-resistant wheat varieties are available. Field sanitation, crop rotation, and summer fallow can be beneficial.Non-host biofumigants may be used as a green manure to reduce nematode populations. Destroy weeds and crop volunteers (especially wheat and barley) that serve as a green bridge during summer fallow. Nematicides reduce nematode populations but are not profitable or environmentally appropriate to use. There are no effective seed treatments.