WSU Extension

Hortsense

Spruce
 
Disease
Oil discoloration of foliage 
Rhizosphaera needle cast 
Rust 
Insect
Coneworms 
Cooley spruce gall adelgid 
Douglas fir tussock moth 
Pine needle scale 
Spruce aphid 
Spruce bud scale 
Spruce budworm 
Spruce needleminer 
Spruce spider mite 
White pine weevil 



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Caption: Pine needle scale
Photo by: A.L. Antonelli
  
Spruce : Pine needle scale
(revision date: 4/11/2018)


Biology
Pine needle scale occurs on the needles of spruce, pine, and true fir. The elongate, flattened scales are white and about 1/16" long. Infested needles are mottled yellow at first, then turn completely yellow and finally brown. Light infestations cause little damage. In heavy infestations the tree may appear "flocked" or "frosted". Severe attacks by pine needle scale may kill branches or the whole tree.
Management Options

Non-Chemical Management
  • On small, lightly infested trees, hand-picking may help remove scales.
  • Where practical, prune and destroy heavily infested branches.
Select non-chemical management options as your first choice!

Chemical Management

Controls are effective only if applied during the early mobile crawler stage of insect development in early spring. Horticultural oils, soap-based products and some other products may cause discoloration of spruce needles, particularly on Colorado blue spruce. Read labels carefully and test on a small area before application. DO NOT APPLY Safer Brand Insect Killing Soap Concentrate II to Colorado blue spruce. 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
  • 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 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: Pine needle scale
Photo by: A.L. Antonelli
Caption: Pine needle scale
Photo by: R.S. Byther