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Cottony leak (Pythium aphanidermatum) affects fruits of most cucurbits but is more common on cucumber and squash. The disease first appears on portions of fruit in contact with soil. Small, water-soaked spots expand rapidly until large portions of the fruit are necrotic and soft. Disease is more severe during warm weather under wet conditions or when soil is saturated. Profuse, white fungal growth resembling tufts of cotton can be found on rotted areas when humidity is high. 

Cottony leak on cucumber.

(Photo: Cheryl Kaiser, University of Kentucky)

Management:

• Use physical barriers (mulches) to prevent fruit from contacting soil.
• Fungicides applied before or at planting may provide some disease suppression.
• Manage excess soil moisture (drainage, irrigation).
• Promptly remove and destroy diseased plant material during the growing season.
• Avoid movement of infested soil to clean fields. 

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