REACTIONS OF LODGEPOLE PINE TO ATTACK BY DENDROCTONUS PONDEROSAE HOPKINS AND BLUE STAIN FUNGI

Abstract

The reaction in lodgepole pine in response to attack by Dendroctonus ponderosae and subsequent infection by blue stain fungi varies with the degree of resistance manifested by the tree. In both resistant and successfully attacked trees a sequence of changes, which increase in space with time, occurs in the inner bark and sapwood. In resistant trees a condition termed secondary resinosis develops which is lethal to bark beetle broods and blue stain fungi. In contrast, successfully infested trees do not exhibit secondary resinosis, and bark beetle broods and blue stain fungi survive and complete their development. In resistant trees blue stain fungi are responsible, directly or indirectly, for the extensive reaction and condition of secondary resinosis which is associated with the insect gallery. Changes in stem tissues associated with wounding are discussed.