Root Disease Threat Minimal in Young Stands of Western Hemlock and Sitka Spruce in Southeastern Alaska. Charles G. Shaw III, Research Plant Pathologist, USDA Forest Service, Forestry Sciences Laboratory, Pacific Northwest Forest and Range Experiment Station, Juneau, AK. . Plant Dis. 73:573-577. Accepted for publication 27 January 1989. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1989. DOI: 10.1094/PD-73-0573.

The development of root diseases in young, managed stands of western hemlock and Sitka spruce in southeastern Alaska has been a concern because organisms that incite root disease are known to occur, and the same root disease organisms cause problems in similar stands in British Columbia, Oregon, and Washington. In this study, however, colonization by Heterobasidion annosum was rare in standing live trees and their survival was poor in inoculated and noninoculated trees and stumps of young-growth Sitka spruce and western hemlock at several locations in southeastern Alaska. Furthermore, H. annosum survived less than 5 yr in naturally infected stumps of either species. The high rainfall and associated high water content of stumps (generally well over 100% moisture content) and low temperatures common to the region appear to limit colonization by H. annosum. In contrast, stump colonization by Resinicium bicolor and presumably saprophytic Armillaria spp. was common, but mortality in adjacent trees was rare. These data suggest there is little likelihood that root disease fungi will damage young, managed stands of Sitka spruce and western hemlock within the current 90- to 120-yr rotation.

Keyword(s): biological species, environmental conditions, wood moisture content.