AbstractIn stands of Lodgepole pine over 6 years old, 68 of stems in Climatic Zones A and B, characterised by a relatively short growing season, and 63 of stems in Climatic Zone C were infected byCrumenula sororia. On individual trees, the number of stem whorls showingC. sororiainfection increased significantly with increasing stand elevation and with decreasing exposure in crops on Alberta and Shuswap Lake provenances over 30 years old, whereas in Shuswap, Long Beach and Vancouver Island stands less than 30 years old, increasing elevation and decreasing exposure had little effect on numbers of infected whorls. The numbers of infected whorls were not related to compartment aspect in crops of Alberta provenance, whereas in stands of Shuswap Lake, Long Beach and Vancouver Island provenances, W, SW and S‐facing compartments showed fewer infections. In contrast the numbers of active cankers showed a positive correlation with increasing compartment elevation and exposure. In Zones B and C, cankers were concentrated on Northerly and Westerly aspects of individual stems. The evidence suggests that particular climatic regimes in different zones of the tree and in different ages of crop may be critical in determining the success of failure of infection by C.sorori
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