VIEW ARTICLE

Ecology and Epidemiology

Inhibition of Wood-Decay Fungi by Wetwood of White Fir. J. J. Worrall, Research assistant, Department of Plant Pathology, University of California, Berkeley 94720, Present address of senior author: Forstbotanisches Institut der Universität Göttingen, Busgenweg 2, 3400 Göttingen-Weende, Fed. Republic of Germany; J. R. Parmeter, Jr., professor, Department of Plant Pathology, University of California, Berkeley 94720. Phytopathology 73:1140-1145. Accepted for publication 7 March 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-1140.

Growth assays of wetwood fluid in vitro suggested that wetwood of white fir is inhibitory to Heterobasidion annosum (= Fomes annosus). Redox potentials and oxygen diffusion rates indicated hypoxic conditions in wetwood, and H. annosum and other decay fungi were sensitive in vitro to such oxygen availabilities. Although C_x cellulase of H. annosum was unaffected by O₂, laccase activity was highly oxygen-dependent, indicating that wood-decay capability may be even more sensitive to O₂ availability than is growth on laboratory media. In addition, low molecular weight organic acids (acetic, propionic, butyric) were present in wetwood in concentrations that inhibited or prevented fungal growth. The data indicated that properties of intact wetwood may substantially restrict or prevent colonization and decay by H. annosum and that individual trees vary greatly in properties influencing fungal growth.