CHEMICAL AND NUTRITIONAL-STATUS OF DWARF MISTLETOE, ARMILLARIA ROOT-ROT, AND COMANDRA BLISTER RUST INFECTED TREES WHICH MAY INFLUENCE TREE SUSCEPTIBILITY TO BARK BEETLE ATTACK

The terpenoid and phenyl propanoid content of xylem resin as well as p hloem nitrogen and carbohydrate levels of lodgepole pine trees infecte d with Armillaria root disease, Comandra blister rust, and dwarf mistl etoe and check (asymptomatic) trees were determined. Comparisons were made to determine if differences existed that might influence their su sceptibility to bark beetle attack. These variables were also contrast ed with respect to aspect (north and south). Five volatiles (tricyclen e, alpha-pinene, camphene, gamma-terpinene, and bornyl acetate) were s ignificantly higher in trees with one or more diseases than in check t rees. Four volatiles (myrcene, camphor, 4-allylanisole, and gamma-terp ineol) were significantly lower in diseased trees. Camphene was the on ly resin constituent found to differ with respect to aspect, with a hi gher concentration on the north aspect of check trees. There were no s ignificant differences in carbohydrate or nitrogen content with respec t to aspect. The cheek trees were found to have significantly higher s tarch, total nitrogen, and free amino-N contents than diseased trees. Trees infected with Comandra blister rust were found to contain lower levels of reducing and nonreducing sugars than the other diseased tree s and the check trees. Changes in terpenoids and phenyl propanoids in trees susceptible to mountain pine beetle attack suggest a biochemical basis for host selection.