Photo by Ralph Byther, Washington State University.

Causes

Photo by Chal Landgren, OSU.

  • Unknown

Signs & Symptoms

Photo by Chal Landgren, OSU.

  • Tan, discolored bands on random needles at the tip of or on the entire needle
  • Affected portions turn reddish-brown, and may be shed if the entire needle is affected.
  • Symptoms present on newly developed needles, often following high temperature events.
  • Secondary organisms can colonize the necrotic tissue.

Where to Look

  • Valley sites and areas prone to high temperatures during shoot elongation

Similar Symptoms As

  • Needle rust
  • Environmental stress

Management Options

  • Plant resistant species or sources.
  • Shade trees during shoot elongation. Shading may reduce symptoms.
  • Do not rely on spray treatments, which have shown limited benefit.
  • Remove highly susceptible trees.

Scouting

  • On noble fir, look for symptoms in upper part of the tree. Damage in other species can vary.
  • Check for development of symptoms after high temperature events (over 85°F).
  • Examine symptomatic needles during late summer and fall. Symptoms are present on all sides of the trees.

Host Susceptibility

host susceptibility graph

  • High susceptibility: Grand fir, Noble fir
  • Low susceptibility: Nordmann fir, Turkish fir

Management Calendar

  • Look for necrotic needles: All year round
  • Check for symptoms, which commonly develop after high temperatures: Mid-June through August
  • Plant resistant species: February through April