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: Rhododendron leafroller
Photo by: Unknown
  
Crabapple : Leafrollers and leaftiers
(revision date: 2/14/2019)


Biology
Several species of caterpillars will roll and tie leaves of fruit trees. Characteristic signs of feeding include leaves that are webbed, rolled, and tied, often with frass in the webbing. Damaged leaves often turn brown and may drop prematurely. The larvae often group together to make nest-like structures of chewed leaves and webbing. Leafrolling and leaftying caterpillars are usually about 1-2" long at maturity.
Management Options


Non-Chemical Management
  • Hand-pick and destroy individual caterpillars when practical.
  • Pinch to kill caterpillars inside rolled leaves.
  • Prune out and destroy nests of caterpillars.
Select non-chemical management options as your first choice!

Chemical Management

Pesticide recommendations are for flowering (non-edible) crabapples. Apply in early spring, but not during bloom. Use a spreader-sticker with liquid Bt formulations. 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
  • Bull's-Eye Bioinsecticide
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 62719-314-56872
  • Monterey Garden Insect Spray [Organic]
    Active ingredient: spinosad (spinosyn A+D)  |  EPA reg no: 62719-314-54705
  • 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 Caterpillar Killer/Trees, Shrubs, & Vegetables Conc
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 42697-23
  • This list may not include all products registered for this use.
Images

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Caption: Rhododendron leafroller
Photo by: Unknown
Caption: Omnivorous leafroller larva
Photo by: Unknown
Caption: European leafroller
Photo by: S.M. Fitzpatrick and J.T. Troubridge
Caption: Obliquebanded leafroller adult
Photo by: J.F. Brunner