(news release) COLUMBIA, Mo. – University of Missouri Extension agronomy specialist Wayne Flanary says about 160 acres of soybean in northwestern Missouri show symptoms of sclerotina stem rot. The MU Plant Diagnostic Clinic confirmed the disease, which can cause large losses in fields with high yield potential.

Also known as white mold, sclerotina stem rot is rare in Missouri. This stem and root disease is usually found in the northern part of the soybean belt. MU Extension soybean specialist Bill Wiebold says he found it in Shelby County in northeastern Missouri as long as 10 years ago.

In the MU Extension publication “Soybean Diseases,” retired MU plant pathologist Laura Sweets says the white mold first shows as a wilting of leaves in the upper canopy. “Leaves may have a gray-green or off-color and wilted appearance,” she writes. White mold often grows on stems and leaves. The fungus may move to seeds and pods.

The disease favors moderate canopy temperatures (less than 82 degrees) and frequent rainfalls that cause high humidity in the canopy.

Research shows that sclerotina stem rot can remain in soil for years, Wiebold says. Seed can be contaminated with sclerotia, the fungus’s reproductive structures. Wiebold’s colleagues at Iowa State University say it may take up to two years for sclerotina to show up from infected seed. Iowa researchers recommend planting two years of corn to reduce viable seeds, although there are no guarantees.

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