Battling Soybean Cyst Nematode

The soybean cyst nematode – or SCN -  is a parasitic roundworm found in the soil throughout the soybean growing regions of the United States. The juveniles penetrate soybean root tissue and establish feeding sites which reduces water and nutrient uptake in the plant. The result is a reduction in yield.

Greg Tylka is a nematologist and professor of plant pathology at Iowa State University. He says the most effective way to manage SCN is by using multiple tactics and switching them up. That includes planting resistant varieties, seed treatments, and crop rotation. Unfortunately, the nematodes are figuring out the common type of resistance.

"And the way we deal with resistant soybeans losing their effectiveness is that the nematodes are building up on the common type of resistance, called PI 88788," he says. "Farmers need to search out the uncommon type of resistance called Peking, and they need to rotate those types of resistance."

Do a soil test for a nematode egg count before planting or after harvest. He also recommends grabbing a spade and checking for evidence.

"They can dig up roots 5-6 weeks after planting and see the little white females with their naked eyes," says Tylka. "It can happen as quickly as 4 weeks after planting if the soil is dry and hot, but if it’s a cool, wet spring I would wait till 6 weeks or so. And you simply dig out some roots, gently knock the soil off, and you’ll see little white objects on there is the roots are infected with soybean cyst nematode."