WSU Extension


Botrytis bunch rot (Gray mold) 
Powdery mildew 
Brown marmorated stink bug 
Cutworms and armyworms 
Grape erineum mite 
Spider mites 
Spotted wing Drosophila (SWD) 

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Caption: Spider mites under microscope
Photo by: L.K. Tanigoshi
Grape : Spider mites
(revision date: 3/10/2017)

Spider mites are tiny, eight-legged mites which may range in color from yellowish to green or red. Several species may occur on grape. They typically feed on the underside of leaves, causing a yellowish stippling or speckling of the leaf. Severe infestations can cause entire leaves to turn yellow and drop, sometimes resulting in considerable leaf loss and reduced yield. Spider mite feeding is usually accompanied by webbing on the underside of leaves and between leaves and stems. Mites are worse in hot, dry, dusty conditions.
Management Options

Non-Chemical Management
  • High levels of nitrogen in the foliage encourage spider mite reproduction. Switch to a slow-release or low-nitrogen fertilizer.
  • Hose mites from plants with a strong stream of water.
  • Predatory mite and insects such as ladybird beetles and green lacewings aid in control of mite populations. Avoid use of broad-spectrum insecticides which kill beneficials.
  • Provide proper culture. Healthy plants are more tolerant of damage, while drought-stressed plants are more susceptible.
Select non-chemical management options as your first choice!

Chemical Management

Apply control measures when mites first appear and repeat applications as necessary. Be certain to thoroughly cover the plant surfaces, particularly the undersides of the leaves.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Safer Brand Insect Killing Soap Conc II [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 42697-60
  • Safer Brand Insect Killing Soap with Seaweed Extract II [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 42697-59
  • This list may not include all products registered for this use.

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Caption: Spider mites under microscope
Photo by: L.K. Tanigoshi
Caption: Spider mite damage on leaf
Photo by: A.L. Antonelli
Caption: Spider mites and eggs under microscope
Photo by: Unknown