I. Introduction: Southern blight, caused by the fungus Sclerotium rolfsii Sacc., is primarily a problem in the Piedmont apple growing region in the southeastern U.S. Sclerotium rolfsii is a widespread pathogen that affects several hundred plant species.

II. Symptoms and Disease Cycle: Sclerotium rolfsii affects the lower stems and roots of apple trees, killing the bark and girdling the trees. The disease is characterized by the presence of a white, web-like mycelium, which often forms at the bases and on the lower stems of affected trees. Tree death usually occurs rapidly.   Light brown to yellow, round sclerotia 1/16 to 1/8 inch in diameter form in the mycelial mat. The fungus is spread by the sclerotia, which also serve as overwintering structures. The disease is most severe on 1- to 3-year-old trees. As the bark thickens, trees become resistant to infection.