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Black rot (Botryosphaeria obtusa) affects leaves, fruit, and branches. Leaf spots (called “frog eye”) appear a few weeks after petal fall. These purple-colored spots reach ¼ inch in diameter, and then spot centers turn tan and fall out. Fruit infections occur before or during bloom, resulting in rot of the calyx (blossom) end later in the season. Brown lesions remain firm and are not sunken. Black fruiting structures called pycnidia are produced across fruit lesions. Infected fruit shrivel and remain attached to trees (mummify). Branches may also become infected and cankers develop.

Black rot lesion with fruiting structures (Clemson - Bugwood.org)
Black rot lesion with black fruiting structures.

(Photo: Clemson, USDA CES, Bugwood.org)

Management:

  • Sanitation (removal of mum-mified fruit and branch cankers)
  • Fungicide sprays

      

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