Soybean cyst nematode (SCN) is a growing threat to soybean fields in Iowa and around the country.

For decades, SCN was effectively managed by using resistant soybean varieties.

But according to Greg Tylka, professor and nematologist at Iowa State University, those varieties have lost their effectiveness, leaving many soybean producers with reduced yields of 5 to 20 bushels per acre in fields infested with SCN.

Damage from SCN often goes...