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: Aphid colony
Photo by: A.L. Antonelli
  
Crabapple : Aphids
(revision date: 2/14/2019)


Biology
Aphids on crabapples may be green or reddish in color. They typically feed near the tip of growing shoots, sometimes deforming leaves and stunting terminal growth. Fruit may also be deformed. These soft-bodied insects are approximately 1/8" long and often produce honeydew, a sweet sticky material. The honeydew may develop a growth of black sooty mold, which is an aesthetic problem but seldom harms the plant.
Management Options


Non-Chemical Management
  • Hand-wipe or prune to control small, localized infestations when practical.
  • Wash aphids from foliage with a strong stream of water.
  • Encourage natural predators including ladybird beetles, lacewings, syrphid (hover) fly larvae, and predatory wasps. Avoid use of broad-spectrum insecticides which kill these beneficial insects.
  • Control honeydew-feeding ants, which may protect aphid colonies from predators.
  • Provide proper nutrition. High levels of nitrogen in the foliage encourage aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer.
Select non-chemical management options as your first choice!

Chemical Management

Pesticide recommendations are for flowering (non-edible) crabapples. Thorough coverage of foliage is important. Use the following when aphid build up is noticed. Use oils during delayed dormant period. 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
  • R-T-U Year-Round Spray Oil
    Active ingredient: oil/pet distillate  |  EPA reg no: 6218-78
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • Safer Brand Garden Defense Multi-Purpose Spray Conc [Organic]
    Active ingredient: clarified hydrophobic extract of neem oil  |  EPA reg no: 70051-2-42697
  • 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: Aphid colony
Photo by: A.L. Antonelli
Caption: Aphid cast skins
Photo by: R.S. Byther