Mild symptoms of nematode damage include stunting, loss of vigor, wilting even when adequate moisture is present and reduced yields. Severe symptoms often mean early plant death and complete loss of production. Several vegetables that are grown in Louisiana are very susceptible to the root-knot nematode. Okra, tomatoes, cucumbers, butterbeans, squash and melons are some of the most sensitive plants. Root-knot nematode isn't active in the soil when temperatures are below 65 degrees Fahrenheit, so vegetables grown in late fall, winter and early spring suffer little if any injury.
Several vegetables have varieties that are resistant to root-knot nematodes.
For example, tomato varieties such as Celebrity, Better Boy, Pelican and Terrific have been specifically bred to have root-knot resistance. Some southern pea varieties such as Kiawah, Magnolia, Mississippi Cream and Mississippi Purple also are very resistant to root-knot nematode. These varieties have worked fairly well for us and help keep the levels fairly low. The LSU AgCenter specialist says southern peas are fairly cheap and can be readily used as a summer cover crop to lower populations of the root-knot nematode. However, if the population levels are low enough at the time of planting, a susceptible crop usually will not be seriously damaged.