Decay of Wood by the Dacrymycetales

Abstract

Thirty-two strains representing sixteen species in the Dacrymycetales were tested for ability to decay wood using the soil block test. Dacrymyces stillatus, D. capitatus, D. dictyosporus, D. spathularia, Cerinomyces ceraceus, Calocera cornea and C. lutea caused considerable decay of wood. Dacrymyces palmatus, D. minor, D. novae-zelandiae and Calocera viscosa decayed wood to a lesser but significant extent. Three distinct types of brown-rot were noted, and one type of white-rot. Some brown-rotting strains were unusual since they were able to remove considerable amounts of lignin. That Heterobasidiomycetes cause insignificant decay of wood has been a prevailing feeling among forest pathologists (Boyce, 1961; Gilbertson, 1980). Very few species have even been considered as possible agents of decay. Within the Auriculariales, only Helicobasidium corticioides Bandoni has had its decay abilities confirmed in culture; it causes a brown pocket rot of softwoods (Davidson and Hinds, 1958). No members of the Tremellales have been tested for capacity to decay wood in culture, but a few have been observed in association with whiterotted hardwood (Macrae, 1955; Lindsey and Gilbertson, 1978). The Dacrymycetales is an order of approximately eighty species, all of which grow on wood. Shields and Shih (1975) studied decay capabilities of three species in this order using a modified soil block test. Strains of Calocera cornea caused weight losses of 40% and 37.9% on yellow birch and 62.3% on red pine; Dacrymyces stillatus 12% and 33.5% on red pine, and Dacrymyces capitatus 3.5% on red pine. All caused brown-rots. Another member of the order, Calocera viscosa causes a heart rot in stumps of Pseudotsuga menziesii (Mirbel) Franco (Siepmann, 1977, 1979) and Larix decidua Miller (Pawsey, 1971) in Europe. This information suggests that members of the Dacrymycetales may be important in decay of wood. There is practical benefit to studying decay abilities within this order since certain species, most notably Dacrymyces stillatus, frequently grow on wood products in service (Buller, 1922; Ramsbottom, 1953; Reid, 1974). This study focuses on three fungi: Dacrymyces palmatus, D. stillatus, and Dacryopinax spathularia. Isolates of thirteen additional species in the order have been screened for ability to decay wood.