Meloidogyne species The Root-Knot Nematodes Damage to Turf.   Meloidogyne species are some of the most common nematode pests of turfgrass. Biology.  Root knot nematode juveniles penetrate the roots where they establish a  feeding site . As they develop, they cause root swellings (galls) and eventually become swollen females, and then the egg-filled cysts characteristic of these species.  Ecology. Root-Knot nematodes are distributed world-wide. Symptoms.   Above ground symptoms of a severe nematode infestation include patches of yellow plants, stunting, and poor growth. Galls or swellings are visible on the feeder roots of root-knot-damaged turf.  Damage to other crops.  Corn, tomato and potato plants are also damaged by root-knot nematodes. Control. Taking care to avoid the introduction of nematodes into the area is the best control strategy.  Fumigant and nonfumigant nematicides may be effective.