WSU Extension


Spruce : Oil discoloration of foliage
(revision date: 4/23/2014)

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

    - hide images

+ Show larger images

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