Black Stain Root Disease in Douglas-Fir in Western Montana. J. W. Byler, Supervisory Plant Pathologist, USDA Forest Service, Cooperative Forestry and Pest Management, Missoula, MT 59807. T. C. Harrington, Assistant Professor, University of New Hampshire, Durham 03824; R. L. James, Plant Pathologist, USDA Forest Service, Cooperative Forestry and Pest Management, Missoula, MT 59807; and Steve Haglund, Forester, Bureau of Indian Affairs, Ronan, MT 59864. Plant Dis. 67:1037-1038. Accepted for publication 4 May 1983. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1983. DOI: 10.1094/PD-67-1037.

Douglas-fir (Pseudotsuga menziesii) roots with black staining of the xylem were found in four root-disease centers in western Montana where previously only Armillaria mellea was thought to occur. Declining trees had mycelial fans of A. mellea at the root collar and often black stain in small, deeply positioned roots. Symptomless Douglas-fir adjacent to declining trees often had only the black stain. Laboratory and greenhouse studies indicated the stain was caused by Verticicladiella wageneri.