Plant Pathology Infobytes

July 16, 1996
Nematodes Could Be Zapping Your Garden

If your garden plants look a little under the weather it's natural to suppose that high temperatures of the past few weeks are taking their toll. However, your garden may be plagued by another problem -- nematodes.

Nematodes are slender, wormlike animals that live in soil, water, and plant tissues. Too small to be seen with the naked eye, they are spread in infested soil on cultivation equipment, in soil moved by water, and on roots of transplants.

Nematodes damage plants by puncturing roots with a needle-shaped stylet, secreting digestive juices into plant cells and sucking the pre-digested contents. Bacteria and fungi enter the roots through nematode wounds and cause severe rotting of plant roots.

How do you know for sure if your garden plants are affected by nematodes? Symptoms include a general stunting, yellowing, loss of vigor, general decline and death. Another indicator is the presence of galls on plant roots which indicate the presence of root-knot nematodes.

Nematodes are least active in winter and most active in summer and early fall. Thus, late fall and early spring garden crops are seldom damaged seriously unless unusually warm days stimulate nematode activity.

The best time to identify a nematode problem is in the summer and early fall. Examine the roots of growing plants for signs of nematode damage at the end of the harvest season. It's best to dig the dig the roots rather than pulling them from the soil. You may need to wash soil from the roots. Compare suspect roots with healthy roots.

The best way to determine if you have a nematode problem in your garden is to collect a soil sample which can be analyzed free at the Extension Plant Pathology Laboratory at Mississippi State University. Take enough soil from around the roots of living plants to make one pint. Enclose some roots along with the soil. The soil should be moist, but not too wet. Place the soil and roots in a plastic bag or a container to prevent drying. Keep the sample in a cool place (not refrigerated) if it is to be held longer than 12 hours.

Check with the County Extension Office for copies of the forms which should be completed and sent along with the soil samples. Samples can be sent directly to the laboratory by the Extension Office. Results are generally available within two weeks.

If the nematode analysis results indicate you have a problem, we will be happy to assist you in developing a control program involving nematode resistant varieties, rotation, and other procedures.


Written by the late Dr. Frank Killebrew

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