Douglas-fir needle blight
- 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
Information on host(s)
Main host(s)
Photos
Rhabdocline pseudotsugae fruiting bodies Alex Craigmyle
Thin crowns on Douglas-fir infected by Rhabdocline pseudotsugae Leo Unger
Defoliation caused by Rhabdocline pseudotsugae Leo Unger
Red-brown spots on Rhabdocline-infected Douglas-fir needles Leo Unger