COMPARISON OF OLEORESIN FLOW IN RELATION TO WOUND SIZE, GROWTH-RATES,AND DISEASE STATUS OF LODGEPOLE PINE

Total flow of lodgepole pine oleoresin was investigated in relation to size of wound, diameter class, disease status, and aspect (north and south). The two wound sizes were 2.54 and 5.08 cm in diameter. The dia meter classes were 15.24, 20.32, and 25.40 cm. The disease classes wer e Armillaria root rot (Armillaria spp.), lodgepole pine dwarf mistleto e (Arceuthobium americanum Nutt. ex. Engelm.), and Comandra blister ru st (Cronartium comandrae Pk.). It was found that the 5.08-cm wound res ulted in almost twice as much resin flow as the 2.54-cm wound after 24 h. No differences in flow were found between size classes with the 5. 08-cm wound. However, there was a general trend for flow to increase w ith an increase in diameter class. The 15.24-cm diameter class had sig nificantly less flow than the other two diameter classes with the 2.54 -cm wound. There was also a general trend for greater total flow on th e north aspect. There was a general trend for greater resin flow in th e diseased trees. It was also found that disease status had a signific ant effect on tree growth. The comandra blister rust trees put on sign ificantly less growth than trees in the other two disease classes, Rad ial growth was also found to be greater on the north aspect of all tre es. Interestingly, the mountain pine beetle (Dendroctonus ponderosae H opkins) usually attacks the north aspect first then spreads or maintai ns a strip attack on that aspect. The role of the constitutive (primar y) defensive system in conifers needs further study to understand the interactions taking place, especially from the host selection point of view during the endemic periods. During epizootic periods resources a re utilized as a result of availability. But during endemic periods, t o maintain the insect populations, host selection would seem critical for survival.