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Market Diseases of Apples, Pears, and Quinces
Spongy Dry Rot

Colletotrichum dematium (Pers. ex Fr.) Grove

Spongy dry rot is a fungus disease of little importance on apples today. It is distributed principally along the eastern seaboard and in the midwest. It usually affects only fallen fruits. The disease is rare on the market.

Rot spots are brown at first but darken as they enlarge. They may coalesce to form black sunken areas, 1/2 to 1 inch or more in diameter, which eventually become roughened by the fruiting bodies of the fungus. The decay, especially when advanced, resembles black rot but is firmer, drier, and more uniformly black throughout.

The causal fungus grows very slowly at low temperatures and apparently cannot penetrate the uninjured skin of apples.