DISEASES OF SOYBEAN - SOYBEAN CYST NEMATODE

At one time, the Wisconsin Department of Agriculture, Trade and Consumer Protection (WDATCP) quarantined Wisconsin counties with soybean cyst nematodes (Heterodera glycines). Today, the nematode has become so widespread that DATCP no longer feels that a quarantine is an effective control for the organism.

Symptoms due to soybean cyst nematode infections can vary widely. In some fields with low levels of the nematode, plants may be asymptomatic except for a reduction in yield at the end of the growing season. When larger populations of the nematode are present, affected plants may appear stunted and yellow as in this photo. Symptomatic plants typically occur in patches, and often are associated with weeds that are able to successfully compete with the weakened soybean plants. In severe infections, plant death can result. Affected plants are often first found near entry points to a field because the nematode has been introduced into the field in contaminated soil clinging to the tires of equipment.