WSU Extension

Hortsense

Apple
 
Disease
Anthracnose and Bull's-eye rot 
Bitter pit 
Burrknot 
Crown and collar rot 
Crown gall 
Cytospora canker 
Fire blight 
Fruit russeting 
Nectria canker (European canker) 
Nectria twig blight (Coral spot) 
Perennial canker (Bull's-eye rot) 
Phytophthora fruit rot 
Powdery mildew 
Scab 
Virus diseases 
Insect
Aphids 
Apple ermine moth 
Apple maggot 
Apple-and-thorn skeletonizer 
Brown marmorated stink bug 
Codling moth 
Cutworms and armyworms 
Earwigs 
Fruittree leafroller 
Leafhoppers 
Leafrollers 
Lecanium scale 
San Jose scale 
Spider mites 
Tent caterpillars 
Tentiform leafminer 



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Caption: Rosy apple aphids
Photo by: R.S. Byther
  
Apple : Aphids
(revision date: 4/11/2018)


Biology
Three aphids are important pests of apple. Green apple aphids feed throughout the growing season on terminals, causing twisted and deformed leaves and stunted shoots. They produce honeydew, a sweet, sticky material which may become covered with sooty mold. Rosy apple aphids are purplish to pink with a powdery gray coating. They feed on leaves and buds, causing curled leaves and distorted shoot growth. They may feed on fruit, causing fruit distortion. Colonies of these honeydew-producing aphids are often found in curled leaves. Woolly apple aphids are pink to purple with a dense, woolly coating of white wax. They feed on trunks, branches, and twigs, often at wound sites, causing bark to become swollen or galled in appearance. These aphids feed on apple roots during the winter and are associated with the spread of perennial canker.
Management Options


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

Chemical Management

Do not make applications after blossoms appear. Soaps such as Concern Insect Killing Soap and Safer Brand Insect Killing Soap may require several applications. Oils such as Ortho Volck Oil Spray can be used during delayed dormant period for controlling overwintering eggs of green apple aphids or rosy apple aphids. Oils are not effective against woolly apple aphids. 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.
  • Azamax Botanical Insecticide, Miticide, & Nematicide [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 71908-1-81268
  • Ortho Volck Oil Spray Dormant Season Insect Killer Conc
    Active ingredient: oil/pet distillate  |  EPA reg no: 239-16
  • 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 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: Rosy apple aphids
Photo by: R.S. Byther
Caption: Rosy apple aphid damage to twigs
Photo by: R.S. Byther
Caption: Rosy apple aphid damage to fruit
Photo by: A.L. Antonelli
Caption: Woolly apple aphid damage
Photo by: A.L. Antonelli
Caption: Woolly apple aphid damage
Photo by: R.S. Byther
Caption: Aphid colony
Photo by: A.L. Antonelli
Caption: Aphid cast skins
Photo by: R.S. Byther