"Soybean fields infested with soybean cyst nematode (SCN) may look healthy above ground, but adult SCN females can be detected on the roots of infected plants during the growing season, which may be contributing to the development of sudden death syndrome (SDS). The adult SCN females fill with eggs and eventually die, changing into hardened cysts that protect the eggs in the soil."
"Farmers often assume that they do not have SCN because the soybeans don’t look sick . . . . This is an unfortunate mistake because SCN numbers are low when the nematode is first introduced into a field, but those numbers increase steadily if left unmanaged."