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Infection of Western Hemlock and Sitka Spruce Thinning Stumps by Fomes annosus and Armillaria mellea in Southeast Alaska. Charles G. Shaw III, Forestry Sciences Laboratory, Pacific Northwest Forest and Range Experiment Station, USDA Forest Service, Juneau, AK 99802. Plant Dis. 65:967-971. Accepted for publication 20 February 1981. 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, 1981. DOI: 10.1094/PD-65-967.

On four young-growth forest sites where airborne inoculum of Fomes annosus had been detected, 182 western hemlock and 182 Sitka spruce were cut and one half of the stumps inoculated with F. annosus. All stumps were examined 615 mo later for F. annosus and Armillaria mellea. Twelve percent of the western hemlock and 16% of the Sitka spruce stumps were infected with A. mellea. Of the stumps inoculated with F. annosus, 11% of the western hemlock and 15% of the Sitka spruce were infected; of the uninoculated stumps, 3 and 12%, respectively, were infected. On 13 experimental thinning plots scattered throughout southeast Alaska, A. mellea occurred in 18% and F. annosus in 1% of 351 western hemlock and Sitka spruce stumps remaining from trees cut 2350 mo earlier. F. annosus was also detected, apparently for the first time, on mountain hemlock stumps.