Root-knot nematodes Meloidogyne spp.
IDENTIFICATION — There are good nematodes that feed on decaying plants and there are bad nematodes that feed on living plants. You won’t see these parasitic worms unless you use a microscope; but you can see the damage they leave behind.
Symptoms of root-knot nematodes include a lack of vigor, wilting foliage and reduced or stunted growth of plants and knotty, swollen galls on the roots. These pests can affect almost any vegetable or ornamental in the garden, especially tomatoes, peppers, carrots and lettuce.
CONTROL — Anything that moves soil around your garden (transplanting, tilling, etc.) can spread nematodes, so clean equipment before moving to a new area. Also, check the roots of new plants — you don’t want to bring in another load of nematodes.
There isn’t a good chemical control for home gardeners to use; fumigants are expensive and require a professional to apply them. Root-knot nematodes are usually found in sandy soil; adding organic matter to your soil will help control them. It’ll also keep your plants healthier and able to manage an attack. A soil test can check for the presence of nematodes, so it’s a good idea to have the soil tested in any new garden areas.
Choose plants marked as nematode-resistant and rotate susceptible crops annually. If you see the letters VFN on seed packets or plant labels, the N stands for nematode resistant. (V and F stand for verticillium wilt and fusarium wilt).