RELATIONSHIPS AMONG JACK PINE BUDWORM DAMAGE, SELECTED TREE CHARACTERISTICS, AND ARMILLARIA ROOT-ROT IN JACK PINE

Trees in a 94-yr old Pinus banksiana stand defoliated by Choristoneura pinus were examined. Healthy tress had heavier root systems, larger root volumes, and larger annual volume increments than top-killed or dead trees in the years prior to elevated tree mortality within the stand. Roots of all the dead trees contained Armillaria ostoyae. Three of 5 top-killed trees and 1 of 5 healty trees were felled by A. ostoyae. There was no clear indication whether infection by root pathogens determines the extent to which trees are damaged following jack pine budworm defoliation, or whether repeated defoliation predisposes trees to root pathogen attack. Numbers of live branches in the crown, radial increment over the past 10 yr and prevalence of Armillaria root rot within a stand may be used to hazard rate stands prior to budworm outbreaks. -from Authors