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Mucor Rot

Mucor piriformis E. Fischer

Infected tissue appears light brown, soft, and watery [Mucor piriformis on decaying pear-TM.tif]. The infection usually develops at wound sites, at the calyx end, or at the stem end of the fruit. Complete decay occurs rapidly under packinghouse conditions and in about 2 months in cold storage [Mucor piriformis on Fuji apples-TM.tif]. Fully rotted apples release large amounts of liquid containing the infective propagules of the fungus, which may spread the disease, but this is relatively uncommon.


Common to all fruit-growing regions in eastern North America.

Similar Species

Mucor rot can be confused with other postharvest disorders; however, no other disease liquefies the fruit as readily.


Harvesting fruit in dry weather, placing fruit in clean bins, and not placing fruit that have fallen to the ground into bins will reduce the incidence of mucor rot. Fungicides applied prior to harvest are generally ineffective. After harvest, removing fallen fruit from the orchard floor will help to reduce the buildup of the pathogen in the field. In the packinghouse, dump tanks and flume water can be treated to reduce spore levels.

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