Feature Article - for release the week of August 17, 2008

Angela Sachson  – Florida Yards & Neighborhoods

 

Control ‘Root-Knot Nematodes’ in the Garden

  Nematodes are everywhere, especially in Florida and especially in sandy Florida soils. Most are good guys, eating bacteria, fungi, and other pests. Some are even sold by the thousand to manage insect pests. These are not our subject today. We are talking about the bad nematodes that feed on plants; parasitic nematodes and, in particular, root-knot nematodes.
 

 Root-knot nematodes attack a wide variety of plants and can become serious pests in the home garden. They are microscopic roundworms that live in the soil and on plant roots. They injure plants by feeding on root cells with their needle-like mouthparts (called stylets). The root system can become damaged to the point where the plant cannot absorb water and nutrients.

  Root-knot nematodes have some favorite vegetables and they may also be your favorites. They are tomato, potato, okra, beans, pepper, eggplant, peas, cucumber, carrot, field peas, squash, and melons.

  They do not like to eat corn, broccoli, cauliflower, cabbage, onions and most cool-season crops. This may be because nematodes like hot weather best.

  The Good and Bad News about Nematodes: The bad news about nematodes is that there is no chemical control available to the home gardener. Once you get them you may well lose your crop, and you don’t have to travel very far from here to find entire Okra crops felled by these guys (they really love okra).

The good news is that there are some things you can do to prevent nematode damage, or at least keep it in check. Here are some of them. Start now, before you plant your fall vegetables.

What you can do  

  Rotate the garden to a new location: If a whole new garden space is not practical; rotate plants so that resistant plants are moved to an area where susceptible ones had grown previously. A couple of years of onions, corn or strawberries will discourage the critters from that area.

  Plant resistant varieties: 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 resistance to nematodes. 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. 

Older transplants are generally more resistant to nematodes than younger transplants. So look for transplants that are a little larger. Inspect the roots of transplants for root-knot galls. Occasionally nematodes can be introduced with contaminated transplants. Just turn that pot over in the store, pull out the plant and look at the roots. If you see bumps leave it there.

  Solarize your plot: Call our Extension service to learn about this easy way to discourage both nematodes and weed seeds.

 Use cover crops: During the summer plant a cover crop that nematodes don’t like to eat . French marigolds are the prettiest. Cover crops also improve the soil, prevent erosion, and increase fertility. Marigolds must be planted as a solid planting, no more than 7-inches apart. They must be grown for at least two months, and then turned under. Keep marigolds free of grass and weeds to prevent nematodes from feeding on weed roots.  In the home landscape, some bedding plants are resistant to root-knot nematodes including zinnia, salvia and marigold and some folks suggest companion planting these in the garden.

  Amend your soil: Organic mat­ter can help prevent nematode damage in several ways. The organic matter increases the ability of the soil to hold water and nutri­ents and improves soil structure. This makes a better environment for most plants and can help the plants survive in spite of nematodes.

  Start your garden a little later this fall: Nematode activity slows as soil temperatures drop. Therefore, vegetables grown in cooler months are not as damaged by nematodes as those grown in warmer months. Become famil­iar with the temperature requirements of the plant and grow as late as possible in the fall.

  Soil tillage and root destruction: Destroy plants and plant roots by pulling up immediately after harvest. Do not let stalks stand through the summer. Work the soil two to four times in summer, allowing the sun and weather to exert their killing effect.

  Container growing: It never hurts to hedge your bets. If you want tomatoes or another special kind of veggie, grow an extra or two in purchased nematode-free potting soil in a container.

  If you need additional information on nematodes, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469. In Highlands County call 863-402-6540 and in Glades County call 863-946-0244.  Okeechobee residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners from 1 to 3 PM on Tuesday afternoons. Go Gators!

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Trade  names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean. Last update: 08/18/2008.  This page is maintained by Dan Culbert