Source: Iowa State University Extension

Soybean varieties that are resistant to the soybean cyst nematode (SCN) are a critical management tool for the pest. Resistance to SCN is conferred by several genes that are transferred into soybean varieties from breeding lines with names like Peking, PI 88788, and Hartwig. There are hundreds of SCN-resistant soybean varieties available to Iowa growers.

Not all SCN-resistant varieties yield equally well in SCN-infested fields, nor do they suppress SCN reproduction to the same extent. SCN resistance is conferred by several genes. Soybean varieties bred from a single resistance source, like PI 88788, do not necessarily possess all of the SCN resistance genes that are in PI 88788. Also, the SCN resistance genes from the different breeding lines vary in effectiveness in controlling the different SCN populations that infest Iowa fields. And no doubt, yield and SCN control provided by the SCN-resistant soybean varieties can vary in response to many other biotic and abiotic factors in field environments.

Original press release.