The northern and southern root-knot nematodes are most common in Oklahoma. The peanut root-knot nematode is not known to exist in Oklahoma but occurs in Texas. Susceptible plants like tomato respond to this feeding by developing galls or knots on roots. Nematodes feeding in a plant root. Infected plants are stunted, appear yellow or pale green in color, and wilt easily, even when soil moisture is adequate.
Severe infestations can dramatically reduce yields and eventually kill plants.
Management of root-knot should focus on sanitation measures for preventing contamination of soils, reducing populations below damaging levels where infestations already exist, and variety selection. Sanitation measures include planting nematode-free tomato transplants and avoiding the introduction of nematodes on any other type of transplant stock or with soil. This is difficult in reality because soil clinging to plant roots may contain nematodes without obvious plant symptoms. Equipment and boots should be washed free of soil before working clean ground when moving from areas suspected of harboring nematodes. Soil fumigants are restricted use pesticides that can only be applied by certified applicators.