After harvest is an excellent time to test for the presence of soybean cyst nematode (SCN) in fields to be planted in soybeans next year, says Greg Tylka, Iowa State University plant nematologist.

"Once infestations are discovered, resistant soybean varieties can be grown to reduce damage and dramatically improve yields," says Tylka. "The key to effective management of SCN is early detection."

As many as 75% of Iowa fields may harbor the yield-robbing pest.

"Soybean fields may be sampled to explain low soybean yields obtained in the 2001 growing season, but cornfields should be sampled this fall in order to detect SCN before next year’s growing season," says Tylka.

Soil samples can be collected anytime after harvest, up until the ground freezes solid or is covered with snow. Samples should consist of 10-20, 6"- to 8"-deep soil cores collected from about 20 acres.

Samples can be sent to the Iowa State University Plant Disease Clinic, 323 Bessey Hall, Iowa State University, Ames, IA 50011, or to private soil laboratories that offer SCN testing.