Douglas-fir needle blight

Douglas-fir needle blight - Red-brown spots on <em>Rhabdocline</em>-infected Douglas-fir needles
  • Latin name: Rhabdocline pseudotsugae Syd.
  • French name: Rouge du Douglas
  • Division: Ascomycota
  • Class: Helotiales
Description

Micro-habitat(s)

Needle

Distribution

Western Canada

Damage, symptoms and biology

Repeated severe infection almost completely defoliates trees, leaving only the current year's needles. The impact of the disease therefore is greatest on small trees because of their smaller total number of needles; large trees usually undergo only light defoliation and sustain little damage. Christmas tree plantations can be severely damaged.

Other information

Douglas-fir needle blight is caused by a number of species and subspecies of the genus Rhabdocline. The most common in British Columbia is R. pseudotsugae described here, and R. weirii (Parker & Reid). The symptoms caused by these organisms are similar, however, so precise identification is seldom important. Epidemic infection years occur in cycles and depend on climatic conditions during the infection period. Occasionally individual trees show marked resistance to the disease.

Canadian Forest Service Publications

Douglas-fir needle blight

Information on host(s)

Main host(s)

Rocky Mountain Douglas-fir

Photos
  • Douglas-fir needle blight Thin crowns on Douglas-fir infected by Rhabdocline pseudotsugae
  • Douglas-fir needle blight Defoliation caused by Rhabdocline pseudotsugae
  • Douglas-fir needle blight Red-brown spots on Rhabdocline-infected Douglas-fir needles
  • Douglas-fir needle blight Rhabdocline pseudotsugae fruiting bodies
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