Growers and those who advise them receive annual prompting to consider collecting soil samples from Iowa fields in the fall to test for the presence of the soybean cyst nematode (SCN). The nematode often causes no obvious aboveground symptoms for many years after being introduced, so many SCN-infested fields can go undiagnosed. The key to effective SCN management is discovering infestations when the nematode population densities are low.