WSU Extension


Cucumber, Pumpkin, Squash
Angular leaf spot 
Cucumber mosaic virus 
Curly top (Beet curly top virus) 
Pollination failure 
Powdery mildew 
Root rot 
Verticillium wilt 
White mold 
Brown marmorated stink bug 
Spider mites 
Squash bug 
Western spotted cucumber beetle 

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Caption: Sclerotinia white mold on bean pods and stems
Photo by: R.S. Byther
Cucumber, Pumpkin, Squash : White mold
(revision date: 6/3/2014)

White mold is a fungal disease which affects stems and fruit of cucumbers and squash. Initial infections commonly occur through dead tendrils, withered flowers on fruit, and dead leaves which are still attached to the plant. After infection, the fungus can spread into living tissues, where it causes a stem blight or fruit rot. White, cottony fungal growth develops on the stems, which later become dry and withered. Small black structures of the fungus may be present in the cottony mats or inside the stem. Affected cucumber fruits develop a soft, watery rot. Disease development is favored by long periods of cool, wet weather. Although widespread, the disease is not a serious concern on squash or cucumber.
Management Options

Non-Chemical Management
  • Plant in well-drained soils.
  • Avoid overhead irrigation.
  • Space plantings to improve air circulation, particularly around the base of the plants.
  • Remove and destroy infected plants. Do not compost diseased plant materials.
Select non-chemical management options as your first choice!

Chemical Management

None recommended


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Caption: Sclerotinia white mold on bean pods and stems
Photo by: R.S. Byther