Three species of true firs in the Pacific Northwest--Abies gran-dis, grand fir; A. amabilis, Pacific silver fir; and A. lasiocarpa,
subalpine fir--are severely damaged or killed by an imported insect
pest, the balsam woolly aphid (Chermes (Adelges) piceae Ratz.), Infestations of this insect cause abnormalities in the wood and, in...
Cambial activity was studied in trees infested by the balsam
woolly aphid and in non-infested trees of grand and subalpine fir.
Infested and non-infested samples of grand fir were collected near
Corvallis during 1968 and 1969. Samples of subalpine fir, noninfested
and infested, were collected near Odell Lake, at approximately...
Infection courts for microorganisms invading white fir heartwood were determined to be primarily branches and basal wounds. Of 11 hymenomycetes isolated from infected trees, only four: Echinodontiurn tinctorium, Phellinus chrysoloma, Pholiota adiposa, and Hericium abietis were of major significance in terms of frequency of infection and damage caused. Two or...