Heart rot of black spruce in Ontario. II. The mycoflora in defective and normal wood of living trees

Abstract

The fungi most frequently associated with heart rot in black spruce stems were the Basidiomycetes Fomes pini (Fr.) Karst., Scytinostroma galactina (Fr.) Donk, Polyporus tomentosus Fr., Peniophora septentrionalis Laurila, and Coniophora puteana (Schum. ex Fr.) Karst. Factors related to the occurrence of these and other Basidiomycetes are assessed. An Ascomycete, Ascocoryne sarcoides (Jacq. ex Gray) Groves and Wilson, was frequently isolated from both clear and defective wood in living black spruce (Picea mariana (Mill.) B.S.P.) stems older than 75 years of age. In laboratory tests this fungus invaded but did not appreciably alter black spruce heartwood, and provided some protection against subsequent decay by F. pini. Evidence is presented that the widespread occurrence of A. sarcoides in mature black spruce stems partly explains the relatively low incidence of defect in this species. The potential use of A. sarcoides as an agent for the biological control of decay in black spruce and other conifers is discussed.