Charcoal rot

Charcoal rot is a disease of the soybean root and stem. Charcoal rot symptoms vary depending on the time of the year that the plant is infected. Usually charcoal rot is develops later in the season but it can cause a seedling disease since the roots of the plant can be infected anytime during the season.  Infected seedlings show a reddish brown discoloration at the soil line extending up the stem that may turn dark brown to black.  Foliage of infected seedlings can appear off-color or begin to dry out and turn brown.  A twin-stemmed plant may develop if the fungus kills the growing point.  Under cool, wet conditions young plants that are infected may survive but carry a latent infection that will express symptoms later in the season with hot, dry weather. In older soybeans symptoms of charcoal rot include early maturation, non-abscission of the leaves, chlorosis and failure to complete pod filling. Microsclerotia can be visible as black specks in the woody parts of the stems and roots. The microsclerotia are released into the soil as infected tissue decays.