Infection and damage occur at any stage of growth. Symptoms include stand reduction caused by seed rots or preemergence damping off. Postemergent symptoms include water soaked lesions on the stem and roots, yellowing of leaves, wilting, and seedling death. Older plants are killed more slowly. The withered leaves generally remain attached.
Lower stems have dark brown lesions that often extend beyond the first trifoliolate leaves.
The disease is best managed by planting resistant cultivars. Numerous races of the pathogen have been identified, but cultivars with resistance to all races are available. Low, poorly drained fields with a history of Phytophthora should be avoided. The cause of SDS is unknown, but a Fusarium species has been implicated. Sudden death syndrome appears to be favored by the presence of soybean cyst nematodes, irrigation, and cool, wet weather.