Effect of inoculum concentration of Endocronartiumharknessii on the infection of lodgepole pine

Abstract

From each of three heavily infected Pinuscontorta (Engelm.) var. latifolia stands, cones were collected and bulked from at least five trees with few or no galls, and from at least five trees with many galls. Two additional seedlots were obtained from single, apparently resistant trees from two of the stands. Five levels of Endocronartiumharknessii spores (2, 7, 20, 60, and 180 mg) were applied per tray of 50 seedlings in four replicated experiments. The number of spores observed on 1 cm long stem sections was directly proportional to the number of spores applied. Differences in infection frequency between seedlots from heavily and lightly infected trees were significant, although not large, based on analysis of the four lowest inoculum concentrations. There was no interaction effect between inoculum concentration and infection frequency of the parent trees.