Penicillium expansum Link
Distribution: Common to all fruit-growing regions in eastern North America.
Fungus on fruit stored under wet or humid conditions produces numerous blue-green tufts of spores on the fruit surface.
Dave Rosenberger, Cornell Univ.
Blue mold enters the fruit through wounds, stem-end invasion, or as a core rot (A). Infection is first visible as a soft and sunken, yellow to pale-brown circular lesion on the surface of the fruit. Lesions expand rapidly and can quickly macerate the fruit (B). A diagnostic symptom of this rot is a strong earthy or musty odor and unpleasant taste. If fruit are stored under wet or humid conditions, the fungus produces numerous blue-green tufts of spores on the surface of the fruit (C); sporulation typically does not occur under CA conditions (compare with gray mold).