In addition, Pratylenchus penetrans increases the susceptibility of potato plants to Verticillium wilt and blemishes tubers. Pratylenchus neglectus is common in potato fields but has not been shown to damage potatoes in California. Stubby root nematodes feed on root surfaces, resulting in formation of numerous stubby roots. The major problem caused by this nematode species is transmission of tobacco rattle virus, which causes corky ringspot disease on developing tubers. The symptoms described below are indicative of a nematode problem, but are not diagnostic because they could result from other causes as well.
Infected plants are likely to wilt earlier under temperature or moisture stress.
Infestations may occur without causing any aboveground symptoms. Feeding by root knot nematode causes characteristic swellings, called galls, on roots. Galls caused by Meloidogyne chitwoodi are small and difficult to see. Meloidogyne hapla causes small distinct galls with proliferation of lateral roots around these galls. Meloidogyne incognita causes more pronounced galls.