Choanephora Wet Rot Wet rot, caused by the fungus Choanephora cucurbitarum, is a fruit rot of summer squash. Fungal mold appears on the infected area, and fruit rot rapidly. The fruit resembles a pin cushion with numerous small, black-headed pins stuck in it. Initially, the heads are white to brown but turn purplish black within a few days.
Symptoms usually begin on the blossom end of the fruit.
Persistence And Transmission. In spring, fungal spores are spread to squash flowers by wind and by insects, such as bees or cucumber beetles. Infection occurs in the blossom and moves into the fruit and stem. Development of wet rot is favored by high relative humidity and excessive rainfall. There are no effective control practices available for wet rot at this time.