Among various fungal diseases that growers may encounter, Botrytis fruit rot caused by Botrytis cinerea is a major disease in humid environment.
Botrytis fruit rot can apparently infect the flower, and then go quiescent.
It will reactivate in the ripening fruit, causing the fruit to soften and then become completely encased in grey mold and spores. Sanitation is the first line of defense to control this. Keeping the crop free of old leaves, old fruit, and other debris that can support Botrytis is of primary importance. Use of fungicides may be important if Botrytis is too prevalent in your crop. Use of an acidified hydrogen peroxide, like Oxidate, can help suppress Botryis on your crop, and has no residual. Other fungicides are listed in the UC Davis site.
Unless otherwise indicated, all of the images in this section are from the UC Davis IPM site and are used with permission from the University of California Statewide IPM Program, Jack Kelly Clark, photographer.