Secondary Resin Production Increases with Vigor of 'Abies grandis' Inoculated with 'Trichosporium symbioticum' in Northeastern Oregon

摘要

Thirty grand fir (Abies grandis (Dougl. ex D. Don) Lindl.) trees were artificially inoculated with the fungal symbiont, Trichosporium symbioticum Wright, to simulate attack by the fir engraver beetle. Scolytus ventralis LeConte. Fifteen months after treatment, secondary resin production, necrotic lesion formation, and percentage of wounds with T. symbioticum were determined in relation to tree vigor and inoculation density. Resin production was significantly greater in high-vigor trees but was not affected by inoculation density or degree of fungal colonization. Lesions from inoculated wounds were significantly longer than lesions from uninoculated wounds. Neither lesion size nor percentage of wounds with T. symbioticum were affected by tree vigor or inoculation density. The study did not establish a threshold of successful attack in grand fir nor did any trees die as a result of treatment. The study is the first attempt to measure secondary resin response in grand fir in relation to two quantified measures of tree vigor and three levels of inoculation density.