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Wood-Decay Fungi Associated with Woodpecker Nest Cavities in Living Western Larch. C. G. Parks, USDA Forest Service, Forestry and Range Sciences Laboratory, La Grande, OR 97850 . E. L. Bull, USDA Forest Service, Forestry and Range Sciences Laboratory, La Grande, OR 97850; G. M. Filip, Forest Science Department, Oregon State University, Corvallis 97331; and R. L. Gilbertson, Department of Plant Pathology University of Arizona, Tucson 85721. Plant Dis. 80:959. Accepted for publication 21 May 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0959A.

Trunks and branches of both living and dead trees decayed by wood-rotting fungi provide nesting sites for woodpeckers (1). Most species of woodpeckers excavate a new nesting cavity every year as part of their breeding biology. Once abandoned by the woodpeckers, cavities are used by a host of other wildlife dependent on cavity habitat. Forest managers are concerned that current management practices do not provide sufficient numbers of suitably decayed trees, over time, to sustain cavity-dependent wildlife. Identifying decay fungi in trees selected by woodpeckers is an important step in determining management strategies. Twenty living western larch (Larix occidentalis Nutt.) located in northeastern Oregon were sampled by climbing and collecting wood cores adjacent to woodpecker nest cavities. Wood samples were cultured on malt extract agar. All nest cavities were associated with decayed wood. No wood-decay fungi were obtained from 7 trees, whereas 7 Basidiomy-celcs were obtained from the 13 remaining trees. Coniophora puteana (Schumach.:Fr.) P. Karst. was isolated from 6 trees; Gloeophyllum se-piarium (Fr.) P. Karst. from 3 trees; Oligoporus placentus (Fr.) R. L. Gilbertson & Ryvarden from 3 trees; Stereum sanguinolentum (Albertini & Schwein.:Fr.) Fr. from 2 trees. Neolentinus lepideus (Fr.) Redhead & Ginns, Phaeolus schweinitzii (Fr.) Pat., and Wolfiporia cocas (Schwein.) Ryvarden & R. L. Gilbertson were each isolated once from separate trees. Three of the fungi found in our survey, G. sepiarium, O. placentus, and N. lepideus, are considered saprophytes and are not known to decay living trees. The other four fungi are reported as facultative parasites and can colonize either living or dead trees if conditions are suitable. For many facultative parasites to become established in a living tree, freshly exposed wood resulting from injuries is essential. Such is the case when Stereum sanguinolentum occurs in balsam fir {Abies balsamea (L.) Mill.) where it is the principal cause of heart rot of the species (2). Information from this and similar studies may be used to develop techniques to inoculate trees for woodpecker use.

References: (1) R N. Conner et al. Wilson Bull. 88:575, 1976. (2) D. E. Etheridge Can J. Bot. 40:1459, 1962.