Melampsora occidentalis

Alternate hosts: black cottonwood, aspen, and hybrids of Populus spp.

Photo by Chal Landgren, OSU.

Signs & Symptoms

Photo by Gary Chastagner, Washington State University.

  • Slight yellowing on infected newly emerging needles
  • Cream to yellow fruiting bodies 2 weeks after initial symptoms
  • Discolored areas become necrotic, and the needles shrivel and shed during the following 4 to 6 weeks.
  • Severely damaged shoots become cankered and die.

Where to Look

Photo by Gary Chastagner, Washington State University.

  • Areas near overwintered, diseased leaves of poplar or other alternate hosts

Similar Symptoms As

Photo by Gary Chastagner, Washington State University.

  • Chemical damage


  • Watch for yellowing on newly emerged needles.
  • Look for yellow-orange pustules in discolored areas of the needles.

Management Options

  • Spray protective fungicide (if needed) on developing shoots.
  • Remove susceptible poplar hosts near Douglas-fir plantations.
  • Select a less susceptible seed source.

Host Susceptibility

host susceptibility graph

  • Medium susceptibility: Douglas-fir only

Management Calendar

management calendar

  • Look for new needles with discolored areas: Mid-April through Mid-July
  • Check underside of new needles for orange structures: May through Mid-July
  • Use fungicides to protect new growth: Mid-April through Mid-May