Choanephora fruit rot

Choanephora fruit rot (Choanephora cucurbitarum) is a plant pathogen affecting cucurbits. Growth of the fungus is accelerated in temperatures above 25°C (77°F) and damp conditions. The condition affects blossoms and fruit, with increased risk to fruit nearer the ground. 30-40% of a plant may be infected with the fungus and while destructive, it only survives as long as the conditions which support it. Subsequent growths are likely to be unaffected provided the conditions are less conducive to it's growth.

Symptoms
Affected fruit are watery and soft. Hairy, white fungal growth appears on the rotted area with purple-black fruiting bodies forming as the disease progresses. The fungus growth resemble small black-headed pins stuck into the fruit, sometimes called "whiskers." Disease development is promoted by high moisture conditions.

Treatment
None. Use of fungicides is not practical as new blossoms open on a daily basis and ideal disease conditions can change quickly.

Prevention
Where possible, avoid humid conditions by promoting air movement; increase plant spacing, provide adequate drainage, avoid overhead irrigation and avoid excess nutrition which creates a dense canopy.

Refrigerated storage and careful handling will minimize decay postharvest.