Cucurbit Wet Rot

Are your squashes rotting on the vine? It may be cucurbit wet rot.

Yellow summer squash infected with cucurbit wet rot (Howard F. Schwartz, CSU, Bugwood.org) CC BY 2.0 US

Cucurbit wet rot is a fungal disease caused by Choanephora cucurbitarum. Also known as Choanephora fruit rot and wet rot, this disease affects members of the melon family, such as pumpkins and cucumbers. Beans, peas, and okra can also be infected.

​Cucurbit wet rot symptoms

Cucurbit wet rot first appears as a soft area on the blossom end of fruit or pods. Those spots can also appear around wounds in the fruit. White fungal growth develops, turning purplish-black and causing the whole fruit to rot. Cucurbit wet rot is often confused with blossom end rot and Rhizopus soft rot.

Blossom end rot looks like leathery, dark areas on the flower end of your fruit. It happens most often on tomatoes. There’s nothing soft or squishy about it. Cucurbit wet rot is wet and squishy and distinctly rotten. Rhizopus soft rot, or black bread mold, is the white fuzz that grows overnight on your grocery store strawberries. It can also occur on sweet potatoes, pears, peaches, melons, and mangos.

Blossom end rot (Mark) CC BY 2.0

Cucurbit wet rot (David B. Langston, UGA, Bugwood.org) CC BY 3.0

Cucurbit wet rot management

Like most rots, cucurbit wet rot needs moisture to become a problem. You can prevent it with good drainage and by allowing the soil to dry out between waterings. Fungal spores can travel on the wind, with insects, or in splashing water. While there isn’t anything we can do about the wind, there are things we can do to prevent wet rot:

• Keep insect populations in check.
• Avoid overhead watering.
• Space plants for good airflow and quick drying.
• Employ crop rotation.

Infected fruit should be removed and tossed in the garbage.