A total of 464 living white and grand fir tree stems in 24 stands in Oregon and Washington were dissected to detect infections of hymenomycetes (decay fungi) and other microorganisms in woody tissue. Of 21,249 attempted isolations from dissected trunks, 43.2% yielded bacteria or yeasts, 38.6% were sterile, 11.0% were nonhymenomycetes, 3.1% were hymenomycetes, and 4.1% were contaminated or mixed cultures. Hymenomycetes most frequently isolated were Echinodontium tinctorium and Heterobasidion annosum, both of which caused the most discoloration and decay. Nearly 20% of all hymenomycetous isolations, particularly Hericium abietis and E. tinctorium, were from clear tissue not associated with discolored or decayed wood. More than 300 trunk wounds on 248 dissected trees were classified by size, location, age, and hymenomycetous associations. At least 45% of all trees with wounds had hymenomycetes present, of which E. tinctorium and Pholiota limonella were isolated most frequently. Discoloration caused by E. tinctorium was associated with wounds as recent as a year or as small as 56 cm². All E. tinctorium infections that caused discoloration or decay were within 30 cm of a wound, whereas all infections within clear tissue were beyond 30 cm. These data support a hypothesis that E. tinctorium enters hosts via minute branchlet stubs, becomes dormant after the branchlet stubs occlude, and is activated by wounds in the vicinity of dormant infections. For. Sci. 33(2):347-355.
Mycologist, Center for Forest Mycology Research, Forest Products Laboratory (maintained in cooperation with the University of Wisconsin), Forest Service, U.S. Department of Agriculture, Madison, Wisconsin