With the soybean harvest near an end, now is the time to think about testing next year”s fields for the soybean cyst nematode.

Testing can help growers make better planting decisions, according to Ann MacGuidwin, a nematologist at the University of Wisconsin-Madison. Trials on soils where nematodes were abundant have shown that nematode-resistant soybean varieties yield as much as 23 bushels per acre more than a susceptible variety. The nematode can reduce soybean yields even when plants appear normal above the ground.

“The only way to know for sure if the nematode is limiting yields is to run a soil test,” MacGuidwin says. “A soil test shows the pest”s population density, which is important for deciding whether or not to plant a soybean variety with resistance to the nematode.”

MacGuidwin”s laboratory at the College of Agricultural and Life Sciences in Madison will analyze samples for the soybean cyst nematode. She uses the test results to help map the nematode”s distribution in Wisconsin. She and her coworkers have begun studies on several Wisconsin farms where the nematode is a problem. In research supported by the Wisconsin Soybean Marketing Board, the scientists are trying to learn more about the pest so growers can manage it successfully.

To collect a soil sample, use a soil probe or hand trowel. Collect 10 to 20 soil cores 6 to 8 inches deep in a zigzag pattern throughout 10 to 20 acres of a field. This pattern is the same one growers often use to collect samples for soil fertility. Dump cores into a bucket and mix thoroughly. After mixing the soil, remove about one pint for nematode analysis.

Growers can send samples to Prof. Ann MacGuidwin, Room 495 Russell Labs, 1630 Linden Drive, University of Wisconsin-Madison, Madison, WI 53706. Please submit samples with the following information: grower name and address, phone number, field name, and any field cropping history. The fee for each sample is $10.

For additional information, contact Ann MacGuidwin at (608) 263-6131, or Adam Kaszubowski at (608) 265-1155.