By Greg Tylka, Department of Plant Pathology and Microbiology
The soybean cyst nematode (SCN) remains a leading yield robber of soybeans in Iowa and much of the Midwest. The presence of SCN in the field may not be apparent by appearance of visual symptoms (aboveground stunting and/or yellowing) for years after the nematode is introduced in a field.
An easy way to check fields for the presence of SCN during the growing season is to look for telltale swollen, white SCN females on soybean roots. The SCN females are small, about the size of a period at the end of a sentence on a printed page. It takes four or more weeks after planting for the first SCN females to appear on roots in the spring.