Symptoms and Signs
Like the fungus that causes Rhizopus fruit rot, Mucor spp. invade the fruit through the slightest wound. The fungus secretes an enzyme that rapidly liquifies the entire fruit. Under conditions of high humidity, the berry becomes covered with a coat of tough, wiry mycelium and black sporulation at the tips of long spore-bearing structures. Mucor and Rhizopus fruit rots closely resemble each other and may be difficult to differentiate in the field.
Comments on the Disease
Because the fungus lives on dead and decaying organic matter, field sanitation is important. The disease is particularly prevalent during periods of warm weather in late summer.
Remove all ripe fruit and plant debris from the field. Remove and destroy all ripe and near-ripe fruit from fields after rains. Use plastic mulch to keep fruit from contacting soil. Practice good sanitation during harvest, packing, transport, and storage, and avoid damaging fruit at all times. Unlike Rhizopus, some Mucor species such as M. mucedo and M. piriformis are not inhibited by cold temperatures.
Field sanitation is extremely important. Handle fruit with care at all times. Remove all ripe fruit from the field at harvest and avoid packing overripe fruit. Be sure when fruit is being picked that the entire fruit is removed from the stem, not leaving behind the fleshy receptacle of the fruit as it can serve as a site for invasion by fungus.
Organically Acceptable Methods
Use sanitation, cultivar selection, and rapid postharvest cooling.
Fungicide treatment is generally not recommended.