Is Heterobasidion annosum Poorly Adapted to Incite Disease in Cool, Wet Environments?

Abstract

An argument is advanced to suggest that infection and damage caused in coniferous forests by Heterobasidion annosum are markedly less severe, and survival of the fungus less common, under cool, wet conditions than in other climates. This premise is supported by the author's incisive insights, experience in southeastern Alaska, and data from this area and from other sources. In general, frequent rains reduce the population of airborne spores and wash many of them from stump surfaces. Cool temperatures reduce evaporation of water which helps to maintain a high moisture content in stumps that hinders development of H. annosum.This cool, wet condition also lowers overall metabolic rates and reduces the availability of oxygen, which further inhibits infection by, and survival of, H. annosum in stumps. In contrast, primarily saprophytic Armillaria spp. survive under these same conditions and, through rather rapid colonization of stumps and roots, limit the opportunity for whatever colonies of H.annosum do become established to spread and incite disease in surrounding trees.

Parent Publication

• Proceedings of the symposium on research and management of annosus root disease (Heterobasidion annosum) in western North America; April 18-21, 1989; Monterey, CA.

Citation

Shaw III, Charles G. 1989. Is Heterobasidion annosum Poorly Adapted to Incite Disease in Cool, Wet Environments?. 014\tIn: Otrosina, William J.; Scharpf, Robert F., technical coordinators. 1989. Proceedings of the symposium on research and management of annosus root disease (Heterobasidion annosum) in western North America; April 18-21, 1989; Monterey, CA. Gen. Tech. Rep. PSW-GTR-116. Berkeley, CA: Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture; p.101-104