MSU Extension Integrated Pest Management

Gray mold

Disease

Gray mold

Botrytis cinerea Pers.Fr.

Distribution: Worldwide; common to all fruit-growing regions in eastern North America.

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Lesions usually start at the calyx or stem end of the fruit or at wound sites as small water-soaked areas. As lesions age, they enlarge, turning from grayish-brown to light brown, and eventually to a darker brown. White or grayish-white mycelium form on the surface of the rot under humid conditions (A); however, little sporulation occurs at cold-storage temperatures. Apples coming out of CA storage appear firm and tan, and when completely decayed, look like baked apples (B) (compare with blue mold).

• Crops Affected: apples, pears

  Management

  Gray mold can be effectively treated with postharvest applications of fungicides (see management options under blue mold).

  Similar Species

  In the absence of sporulation, gray mold can be confused with other post-harvest diseases such as blue mold. The rotted tissue tends to be firmer than tissue infected with blue mold and does not separate easily from healthy tissue. Unlike blue mold, gray mold-rotted fruits have a relatively pleasant odor rather than a musty odor.