WSU Extension

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Caption: Spider mites under microscope
Photo by: L.K. Tanigoshi
  
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Apple : Spider mites
(revision date: 2/14/2019)


Biology
European red mites and other spider mites can cause damage in apple trees. The European red mite is a tiny red mite. Other spider mites vary in color from yellow to green to black, depending on species and age. Spider mites typically feed on the underside of leaves, causing yellowish to brown speckling of the leaves. Mites are usually accompanied by webbing on and between leaves and twigs. European red mites produce less webbing than other species. Mite infestations are worse in hot, dry, dusty conditions. Heavy infestations can cause leaf drop. Apple rust mites may also be present and may cause russeting of 'Golden Delicious' fruit. The presence of rust mites is often considered advantageous, as they are a food source for predatory mites which help control spider mite populations.
Management Options

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

Chemical Management


Apply when mites are present. Avoid making applications when blossoms are present. Soaps may require several applications. Horticultural oils are most effective against the egg stage (delayed dormant period) of the mite life cycle and only on European Red mites, not on two-spotted mite. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • All Seasons Horticultural & Dormant Spray Oil Conc [Organic]
    Active ingredient: oil/pet distillate  |  EPA reg no: 4-80
  • Bayer Advanced Natria Neem Oil Conc [Organic]
    Active ingredient: clarified hydrophobic extract of neem oil  |  EPA reg no: 70051-2-72155
  • Hi-Yield Dormant Spray
    Active ingredient: oil/pet distillate  |  EPA reg no: 7401-428
  • 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.
Images
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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 mite webbing
Photo by: A.L. Antonelli