Symptoms can be hard to spot
“For soybean growers, the one advantage of SDS is that it causes foliar symptoms, allowing growers to see there’s a problem,” says Bond. Foliar symptoms of SDS include interveinal necrosis and chlorosis (brown or yellow spots on leaves) and sudden leaf drop with petiole retention.
SCN, on the other hand, often does not present any visible symptoms, and farmers may not realize it’s in their fields. Soil testing and observation of female nematodes and cysts on the roots are the most accurate ways to diagnose an SCN infestation in the field. By the time nematode infestations become severe, soybean plants appear generally stunted with yellowing leaves.
Sudden Death Syndrome (SDS) on the left and Soybean Cyst Nematode (SCN) on the right