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: Discoloration on older foliage from oil application
Photo by: R. Maleike
  
Spruce : Oil discoloration of foliage
(revision date: 4/23/2014)


Biology
Oil discoloration of spruce foliage is suspected when trees which normally have blue-green needles instead have bright green needles. Use of spray oils (to control insects, for instance) can permanently remove the waxy coating which gives the tree its blue color, allowing the underlying green of the needles to show through. The distribution of the discolored needles on the tree may be spotty. There is no harm to the tree; however, some aesthetic value may be lost. Growth occurring after the oil application will be blue.
Management Options


Non-Chemical Management
  • Do not use spray oils or other oil-based products on or upwind of blue-needle spruces.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Discoloration on older foliage from oil application
Photo by: R. Maleike