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: Verticillium wilt on squash
Photo by: R.S. Byther
Cucumber, Pumpkin, Squash : Verticillium wilt
(revision date: 6/3/2014)

Verticillium wilt is caused by a fungus which can persist in the soil for many years. It has a broad host range, including many vegetables (potato and tomato are favored hosts), woody and herbaceous ornamentals, fruit trees, and weeds. Typically, the fungus attacks the roots and moves throughout the plant via the vascular system. Symptoms may not be noticed until plants are stressed. Leaves wilt and develop yellow, V-shaped areas along the margins. Affected leaves die. The wilt progresses upward through the plant and may kill entire vines. Discoloration of the vascular system is noticeable when cuts are made into stems near the base of the plant. Cool soil temperatures favor disease development.
Management Options

Non-Chemical Management
  • Rotate crops. Do not follow potato and tomato with squash or other wilt-susceptible plants in crop rotations.
  • When possible, delay planting until the soil is warm.
  • Clean up plant debris and destroy or discard (do not compost) diseased materials.
  • Resistant cucumber and squash varieties are not available.
Select non-chemical management options as your first choice!

Chemical Management

None recommended


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Caption: Verticillium wilt on squash
Photo by: R.S. Byther
Caption: Verticillium wilt on pumpkin leaves
Photo by: D.A. Inglis
Caption: Verticillium wilt sclerotia
Photo by: D.A. Inglis
Caption: Vascular discoloration from Verticillium wilt on impatiens
Photo by: R.S. Byther