WSU Extension

Hortsense

Crabapple
 
Disease
Powdery mildew 
Scab 
Stem rot 
Insect
Aphids 
Apple-and-thorn skeletonizer 
Leafrollers and leaftiers 
San Jose scale 
Spider mites 



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


Biology
Spider mites on crabapple vary in color. They may be yellow, green, red or brown. They have eight legs and are very small, appearing as moving dots when viewed through a hand lens. Spider mites often feed on the underside of leaves, causing yellowish to bronze stippling or speckling. Fine webbing may be present on leaves or in branch crotches. Hot, dry, dusty conditions are especially favorable for development of severe infestations.
Management Options


Non-Chemical Management
  • Wash spider mites from plants with a strong stream of water.
  • Provide adequate irrigation and proper plant nutrition. High levels of nitrogen in the foliage encourage mite reproduction. Switch to a slow-release or low-nitrogen fertilizer.
  • Natural predators such as ladybird beetles and predacious mites help control spider mite populations. Avoid use of broad-spectrum insecticides which kill beneficials.
  • Plant ground covers to help prevent dusty conditions.
Select non-chemical management options as your first choice!

Chemical Management

Pesticide recommendations are for flowering (non-edible) crabapples. Apply in late spring if mites are present and moving. 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 2-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
  • Hi-Yield Dormant Spray
    Active ingredient: oil/pet distillate  |  EPA reg no: 7401-428
  • Safer Brand Insect Killing Soap Conc II [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 42697-60
  • 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