The soybean cyst nematode (SCN), Heterodera glycine is a serious threat to South Dakota soybean production. It was first detected in South Dakota in Union County in 1995, and in 1996 it was also found in a number of fields in Turner County. It very likely is also present in several other southeastern South Dakota counties.
SDSU Cooperative Extension Service
Smolik, James D. and Gillie, John P., "Soybean Cyst Nematode" (2007). SDSU Extension Special Series. 5.