MSU Extension Integrated Pest Management

Southern blight

Disease

Southern blight

Sclerotium rolfsii Sacc.

Distribution: Mostly a problem from the Carolinas southward.

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Trees attacked by the fungus show a general decline (A). In the early phase of disease, a dense mat or web of white mycelium is evident at the base of the tree (B). The mycelium eventually disappears and leaves behind masses of hardened, fungal bodies called sclerotia (C). The sclerotia are globular, vary in size from 0.5–2.0 mm in diameter, and are at first white in color and turn tan to reddish or dark brown as they age.

• Crops Affected: apples, cherries, peaches, plums

  Management

  The fungus is a natural and resilient inhabitant of many soils in the south. It is best to avoid establishing orchards in locations that have a history of the disease. Young trees are most susceptible to attack.

  Similar Species

  Any disease or disorder affecting the root system or rootstock/scion union can produce similar above-ground symptoms. The presence of mycelium or sclerotia at the base of the tree can be used to distinguish this disease from similar disorders.