Eddie Wheeler

Root-knot nematodes affect a wide variety of vegetables in the garden. These nematodes can cause tomato, okra and other vegetable plants to perform poorly. Nematodes are microscopic slender round worms that live in the soil and feed on and damage plant root systems.

Nematode damage can easily be mistaken for other growth problems such as nutrient shortage, drought stress, disease or just poor growing conditions. Infected roots are unable to absorb nutrients and water, leaving the plant weak and susceptible to diseases. Nematode damaged plants become stunted, turn yellow and wilt in hot weather however, do not depend on plants symptoms alone when trying to determine if nematodes are damaging your plants.

One way to determine root-knot nematode infestations is to pull up a plant and look at its roots. The signs are galls resembling knots. It takes a microscopic examination to identify nematodes positively. Root-knot nematodes can affect a variety of vegetables.

If the roots of some of the susceptible vegetables such as okra, beans and tomatoes have knots or galls, take a nematode sample. August through November is a good time to sample because the nematode population reaches its peak at this time.

Prevention is the best approach to control nematodes in home gardens. Crop rotation, resistant varieties, sanitation and soil solarization are measures that will help reduce the nematode population. There are no nematicicdes on the market that can be used by homeowners.

Rotation is very valuable in reducing root-knot nematode damage; sometimes space may limit the ability to rotate garden sites. Rotate the garden site if possible every few years and also rotate crops within the garden site each year.

Using resistant varieties is the easiest, least expensive and most effective means of nematode control. Plant only resistant varieties of vegetables. Look for “VFN” when purchasing tomato plants. Root-knot resistant varieties are noted by the “N” following the variety name.

Sanitation helps reduce nematode populations. As soon as the plot has been cleaned of its harvest, remove all crop residues.

Soil solarization offers effective control of nematodes. Solarization is the use of clear plastic and heat from the sun to trap heat in the soil. Several weeks are required so that the temperatures become high enough to kill the soil pest.

Two publications that can be helpful with the control of nematodes are ANR-300 Nematode Control in the Home Garden and ANR-713 Soil Solarization for the Control of Nematodes and Soilborne Diseases can be found on our website (aces.edu) or at the County Agent’s office.

Eddie Wheeler is the Marshall County Extension Service coordinator.

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