An exploration of ringbarking to reduce the severity of Armillaria root disease in logged areas in British Columbia

Ringbarking is a girdling technique that is used prior to timber harvesting to reduce losses to Armillaria root disease in some parts of the world. The technique had not previously been evaluated in British Columbia, Canada. Small plots of primarily Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees that were ringbarked prior to timber harvesting had approximately 50% lower levels of Armillaria root disease caused tree mortality in young trees after 15 years than plots of trees that were not ringbarked. Ringbarking did not reduce Armillaria root disease in this trial as much as has been reported in other research. This could be attributable to the centre of the small plots being within 5-10 m of live and dead Armillaria-infected trees in the surrounding forest. The treatment did reduce the severity of the disease by both statistically and biologically significant amounts and, therefore, warrants further investigation as a possible treatment where timber harvesting is conducted in Armillaria root disease affected stands.