In the Furrow
Sampling for Nematodes
By Will Duffie County Extension Coordinator

Burke County farmers produce an array of crops from cotton and hay, to beef and dairy cattle. Due to the size of B u r k e County an assortment of soil types can be found from one side to the other which allows producers spread risk. On the other hand, many of our soils tend to be a good host for damaging nematodes. Nematodes are microscopic worms that feed on plants roots. These pests are so small a handful of soil can contain thousands of these troublesome creatures.

If you have dealt with nematode you already understand why they are such a problem. Nematodes cause economic damage to many of our row crops, turf grasses, ornamentals, and vegetables. These parasites feed on the roots depriving plants of nutrients leading to plant decline or death.

The leading economic impact from nematodes in Burke County is on cotton production. Of the 20,000+ species of nematodes, the southern rootknot, reniform, and columbia lance nematodes are the most troublesome to Burke County cotton producers. Recent nematode surveys in Burke County show that 56.8 percent of the fields surveyed contained some level of southern root-knot nematode, 37.8 percent contained Columbia lance, and 16.2 percent contained reniform nematode. Common yield losses range from 10 to 25 percent, and may exceed 50 percent on heavily infested locations.

Numerous research and on-farm trials have led to the development of a treatment threshold for all crops.

Sampling is the next step and most important step in a management program. Nematodes populations fluctuate during a year. Certain months are better for sampling. The optimum time to sample cotton fields is during October and November and for peanuts from September to October. The proper time to sample additional crops is available at our office.

It is best not to sample from December to March because nematodes overwinter as eggs and laboratory assays do not detect nematode eggs. Winter samples may identify certain species as being present in the field, but does not mean that they are not present. Because of these limitations, do not collect samples during the winter.

To take a soil samples for a nematode assay sample in the root zone to a depth of about 8 inches. Take 25 to 30 cores from each 4 to 5 acres and thoroughly mix the cores together. Place 11/2 to 2 pints of the soil in a plastic bag immediately and keep the soil cool. Take samples when soil moisture is right for good seed germination and be sure not to take samples from extremely dry soil. Be sure not to allow samples to get hot or dry. If samples sit in direct sunlight or in a hot vehicle the nematodes may be killed. Nematodes must be alive for the lab procedure to work. Bring the soil and complete an information form at county extension office.

For more information on nematodes and management practices contact the UGA Burke County Extension Office at 706-554-2119.