Steps in collecting soil samples for nematode detection

Proper collection, packaging, and shipment of plant specimens are extremely important to successful diagnosis of plant disease problems. Inappropriate specimens, specimens arriving desiccated or in advanced stages of decay, or specimens damaged in shipment are of little or no use in attempting to diagnose plant disease problems. The most rapid and accurate diagnosis results from proper specimen collection and shipment, together with submission of complete background information concerning the problem. It is essential that the diagnostic form be filled out as completely as possible.

The following procedures are suggested to insure that the specimen arrives at the laboratory in the best possible condition:

1. Any area in which plants do not grow properly may be infested with nematodes. Infested areas are often circular or oval. Take plant samples from both the obviously stunted area and the apparently healthy area. Plainly mark these samples and keep them separate.



2. Take samples 4 to 12 inches deep in the plant root zone. Do not take samples from the upper 2 inches of soil. When taking soil samples, use a spade, soil auger, or soil sampling tube. Scrape litter from the surface. To use an auger or tube, bore 4 to 10 inches into the soil. To use a spade, dig a V-shaped hole and take a 1/2 inch slice of soil from the smooth side of the hole.



3. Take soil samples any time of the year when the soil is not frozen or when there is sufficient moisture for cultivation. Samples taken after harvest are more reliable than those taken during winter months or early spring before roots develop. Soil that is excessively wet or dry will not give accurate nematode determinations. The optimum soil moisture content for sampling is when soil is friable and crumbly.

Take samples according to plant growth or soil type. Sample distinct areas separately because fumigation may not be required on the whole field.

Finally, transfer soil sample to a plastic bag. Do not add water. Place the plastic bag in a small cardboard box for shipping to the laboratory. Fill out the information sheet completely. Enclose the completed information sheet and the $30 nematode testing fee in an envelope, and attach the envelope to the outside of the package containing the samples so that both will reach the laboratory together. The attached envelope must also have standard letter postage.

Mail to:

Note: All Diagnostic Lab forms are normally available from the county extension agent in each county. Forms are also available by contacting the TPDDL.

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