Ask the Master Gardeners Oct. 2011
Guadalupe County Master Gardeners is responsible for this content, which is not edited by the Wilson County News or wilsoncountynews.com.
Q: I’m afraid that I have nematodes. My tomatoes and okra did not do well this spring and when I pulled them up, there were nodules all over the roots. What should I do now?
A: As you have discovered, tomatoes and okra can be very susceptible to nematodes. Crops that may be severely damaged are tomato, pepper, okra, watermelon, cantaloupe, onion, pumpkin, squash, sweet potato, sweet corn, carrot, eggplant, bean and pea. Root-knot nematodes also feed and multiply on many garden weeds (which you need to know so that you can keep your garden free of weeds).
According to the University of Arkansas Extension Service, certain varieties of common garden crops can be resistant to root-knot nematodes. So when you buy tomato plants, pepper plants, okra seed, bean seed or pea seed, read the variety label to see if it says anything about nematode resistance. The label may list the capital letters VFN. These letters indicate that the variety has resistance to certain diseases: V = Verticillium wilt resistant; F = Fusarium wilt resistant; and N = root-knot nematode resistant. The nematode resistance gene tends to be less effective during hot weather, when the southern root-knot nematode is the most active. Although resistant varieties will perform better than susceptible varieties under these conditions, early planting would help.
After cleanliness (don’t move soil from one garden to another; clean tools between gardens), there are several actions you can take. Rotate crops. Broccoli and cauliflower can lower root knot numbers. French marigolds can help. Keep garden weed free. Solarize garden (although that, to me, is a last resort as it kills everything). Increase the organic matter in the soil as this encourages the growth of numerous fungi, bacteria
and beneficial nematodes and provides some level of biological control for root-knot nematodes.
I am growing Elbon or cereal rye this year in one of my vegetable beds that is overrun with root-knot nematodes. Seed can be found at local nurseries and co-ops. Elbon rye is a trap crop. According to Jerry Parsons in “Cereal Rye for Nematode Control,” once nematodes enter the cereal rye roots, they cannot escape and are doomed. When cereal rye decomposes, it releases organic acids and stimulates soil microorganisms which further reduce the nematode population. Sow seed on top of the garden soil and rake in at the rate of 3/4 to 1 pound per hundred square feet of garden area to insure good coverage and adequate growth. Be sure to water regularly and lightly fertilize every three weeks to encourage maximum growth. What you are striving for is the root system rather than the top foliage. Mow or shred (weed eater) the cereal rye before it forms seed heads and till in one month before planting your spring garden so the massive root system will have adequate time to decompose. Good Luck!
If you have a question to be answered, call the Master Gardeners at 830-379-1972 or leave a message to be answered. The website is guadalupecountymastergardeners.org. The Master Gardener research library is open Mondays from 8:30 to noon, on the second floor of the Texas AgriLife Extension building, 210 East Live Oak in Seguin.