Sampling Garden Soils for Nematodes

Plant Pathology Infobytes

October 10, 1996

If you haven't had your vegetable garden checked for plant parasitic nematodes this season, the fall is a great time to take care of this important gardening chore.

Plant parasitic nematodes are microscopic creatures which have the nasty habit of feeding on the roots of susceptible varieties of tomatoes, peppers, beans, cabbage, cantaloupes, and many other popular types of vegetable crops grown in southern gardens. During their feeding activities, the nematodes actually "suck" the juices from plant roots and cause extensive damage to the root system.

Nematode injury to roots reduces uptake of water and nutrients from the soil. Typical above-ground plant symptoms are general stunting, yellowing, loss of vigor, reduced yield, and overall poor plant performance. The most common underground symptom in gardens is root-knot galling.

Since nematodes are microscopic, they cannot ordinarily be seen with the naked eye. This means you won't know for sure if these pesky critters are causing problems in your garden until soil samples have been collected and analyzed.

How do you collect soil samples for nematode analysis? The following guidelines for sample collection should be followed:

The best time for sample collection is during the fall or early winter.
Pick a time when the soil in your garden is moist but not too wet. For example, do not collect soil samples when there is standing water present.
Use a spade, soil collection probe, or similar sampling device to collect samples. If possible, collect the sample from the center of the old rows.
Collect and place in a gallon sized container at least 20 small samples (about 1/4 to 1/2 cup each) from 6 to 8 inches deep.
Collect one sample per 5,000 to 10,000 square feet of gardening area. Ten thousand square feet represents about 1/4 acre. The key point is to collect a sufficient number of these small samples to give a representative picture of the nematode situa- tion across the entire sampling area.
Mix this soil thoroughly and put about one pint in a nematode soil sample bag (available from your County Extension Office) or in a plastic freezer bag and seal.
Mark the sample number on the collection container.
After collection, samples must be cared for properly until sent to the Nematode Analysis Laboratory for processing.
Soil samples for nematode analysis should be regarded as perishable and handled accordingly. Keep samples in a cool place; exposure to temperatures over 100 degrees F., even for a short time, kills some species of nematodes.
Fill out a Nematode Soil Sample Form (available from your county Extension office) and place in plastic bag or envelope. Do not allow the form to remain in contact with the samples since moisture will destroy the form.
Take the samples to your local Extension Office for routing to the Nematode Analysis Laboratory at Mississippi State University.
Expect to receive sample results in approximately two weeks; nematode control recommendations will be provided if problems are detected through the analysis.
Contact your county Extension office if you have questions on the nematode collection procedure or need information on how to set up a nematode control program.

Infobytes newsletter was written by the late Dr. Frank Killebrew, Extension Specialist.