WSU Extension

Hortsense

Arborvitae
 
Disease
Berckmann's blight 
Cedar flagging 
Leaf blight 
Shoot tip dieback 
Twig blight 
Insect
Cypress tip moth 
Flat-headed and shothole borers 
Juniper scale 
Juniper webworm 
Leafminers 
Spider mites 
Spruce bud scale 



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Caption: Spruce bud scale
Photo by: A.L. Antonelli
  
Arborvitae : Spruce bud scale
(revision date: 3/10/2017)


Biology
Spruce bud scales are shiny brown insects found on the twigs. Heavily infested plants may appear yellowish or show other signs of stress. New growth may be stunted or lacking. Adults are 1/8"-1/4" in diameter and roughly turtle-shaped. Crawlers (immature scales) are flatter. Scales produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a growth of dark sooty mold. Spruce bud scale is a common pest in the landscape, infesting spruce and pine as well as arborvitae.
Management Options


Non-Chemical Management
  • Natural enemies such as ladybird beetles and green lacewings help control scale populations. Avoid use of broad-spectrum insecticides which kill these and other beneficial insects.
  • Hand-wipe to help control minor infestations.
  • Prune and destroy heavily infested branches, when practical.
Select non-chemical management options as your first choice!

Chemical Management

Monitor for immature crawlers when new shoots expand. Apply shortly after crawlers are detected. Do not apply soap products to plants stressed by drought or when tender new foliage is present. Do not apply soaps in full sun or when temperatures exceed 90 degrees F. 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.
  • Bonide Systemic Insect Control
    Active ingredient: acephate  |  EPA reg no: 239-2461-4
  • 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: Spruce bud scale
Photo by: A.L. Antonelli