Root Lesion Nematodes (Pratylenchus species)

Root-lesion nematodes (RLNs) are migratory endoparasites (Pratylenchus species) that move freely in and out of roots. 

Damage: These nematodes don’t blemish tubers, but they can make plants less vigorous and reduce yields. Damage is directly related to the number of nematodes present, and potatoes can tolerate low numbers without significant issues. 

Control: The recommended treatment threshold often depends on the species; it can be as low as 50 nematodes per 100 cc soil for P. penetrans, or as much as 500 nematodes per 100 cc soil for the less aggressive P. neglectus. Pratylenchus penetrans is one of the more destructive species, and it is known to interact with the soilborne fungus, Verticillium dahliae, to cause and increase the severity of early dying disease. Aggressive management of the nematode is recommended when both P. penetrans and V. dahliae are found in the soil, so the treatment threshold may be set as low as 25 nematodes per 100 cc soil.