A NEEDLE BLIGHT OF DOUGLAS FIR 



By James R. Weir, 



Forest Pathologist, Office of Investigations in Forest Pathology, Bureau of Plant Industry, 

 United States Department of Agriculture 



The fungus described in this paper has been under the writer's obser- 

 vation since 1911. The damage resulting from its activities in forest 

 and nursery since the date of its first discovery has been so great that 

 some mention should be made of it at this time. During the past season 

 (19 1 6) the fungus has been so aggressive in its attacks that strenuous 

 efforts must be made to prevent serious injury to Douglas fir \Pseudotsuga 

 taxifolia (Lam.) Britton] in the nurseries. The wide distribution of this 

 fungus in the forests of the Northwest and its destructive effects on 

 young Douglas fir, from seedlings to the 30-year class, have recently be- 

 come of great concern to foresters. Much material and many letters 

 regarding the disease have been received at the Missoula laboratory from 

 all parts of the Northwest. It is highly instructive to quote from a few 

 of these communications. Mr. J. B. Seely, Forest Supervisor of the 

 Helena National Forest, writes, under date of April 23, 1915: 



The affected timber, Pseudotsuga taxifolia, covers an area of several hundred acres 

 in sees. 7, S, and 9, T. 5 N., R. 5 E., having a northern exposixre at an altitude of 

 about 6,500 feet. The affected area is within a pure stand of Douglas fir, and has not 

 increased in any way since first observed nearly two years ago. 



Through more recent reports and through observations in this region 

 by the writer, other infected areas have been discovered. Mr. J. B. 

 Lafferty, Forest Supervisor of the Weiser National Forest, Idaho, under 

 date of February 16, 191 5, writes: 



Assistant Forest Ranger E. E. McGinnes, in whose district the disease seems to be 

 most prevalent, reports that seedlings and saplings that were badly affected in 1913 

 died from the effect during the past season; and that the disease is apparently spread- 

 ing and attacking larger trees. 



Mr. John A. Pearson, Forest Supervisor of the Salmon National Forest, 

 Idaho, under date of June 7, 1915, writes that: 



On December last the disease was first noticed on a ridge on the west side of the 

 North Fork of the Salmon River. Since then it has spread to the east side of the 

 river and down both sides for a distance of about 3 miles. The yellow pine does not 

 seem to be affected in any way and very few of the older fir {Pseudotsuga taxifolia). 

 Trees from 2 to 20 feet in height seem to suffer most. Some of the trees are nearly 

 bare of foliage, and while it is too early yet to determine whether or not they will die, 

 it seems probable that they will. Infection occurs in spots of from 3 to 20 acres in 

 area, or wherever the reproduction is the best. 



A great deal of material was examined from the regions not visited by 

 the writer. 



Journal of Agricultural Research, Vol. X, No. 2 



Washington, D. C. July 9, 1917 



jb Key No. — 117 



98973°— 17— 4 (99) 



