Douglas-fir

Photo by Gary Chastagner, Washington State University.

Causes

Photo by Gary Chastagner, Washington State University.

  • Unknown

Signs & Symptoms

  • Yellow-green mottle syndrome on needles of all ages
  • Initial symptoms after shoot elongation
  • Yellow-green blotches may be small or cover the entire needle; midrib is never affected.
  • Affected needles usually fall off the trees, sometimes causing severe defoliation.

Where to Look

  • Localized areas in the field with trees showing needle loss

Management Options

  • Do not spray; sprays are not effective.
  • Give affected trees a chance to outgrow the mottling; trees sometimes outgrow the syndrome in 2 or 3 years.
  • Remove and destroy trees that are affected every year.

Similar Symptoms As

  • Mite damage
  • Nutrient deficiency
  • Spray damage