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Extension > Garden > Yard and Garden > Vegetables > Diseases of cucurbits > Choanephora rot

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Choanephora rot

Michelle Grabowski

Choanephora Rot, also known as blossom end rot or wet rot, is a disease most commonly found on summer squash under wet conditions. This disease has been seen occasionally on other cucurbits including pumpkin and vegetable marrow.


plant with end covered in black fuzz

M. Grabowski, University of Minnesota

Important biology

Choanephora rot is caused by the fungus Choanephora cucurbitarum. The fungus survives from season to season in crop debris and is spread to new flowers by insects, splashing water, or wind. Infection most commonly occurs on flowers, although the fungi can also infect through wounds on the fruit. Infected flowers are soft, rotted and quickly become covered with first white then purplish black fungal growth. In female flowers, the infection progresses into the fruit and results in soft water rot of the blossom end of the squash. The fungus thrives in wet conditions.


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