Effects of prescribed burning on the viability of Armillaria ostoyae in mixed-conifer forest soils in the Blue Mountains of Oregon
Filip, Gregory M.
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This study evaluated the influence of prescribed burning, soil depth, antagonistic fungi (Trichoderma harzianum Rifai), and time since burning on the viability of the root pathogen Armillaria ostoyae (Romagnesi) Herink in wood pieces buried in the soil of a mixed-conifer forest in northeastern Oregon. Red alder (Alnus rubra Bong) stem segments colonized with A. ostoyae were buried at two soil depths in plots that were burned and not burned. Half of the Armillaria segments were buried with segments of T. harzianum. Prescribed burning in the fall significantly reduced the recovery of A. ostoyae immediately after the burn at a soil depth of 8 cm but not at a soil depth of 30 cm. Adding T. harzianum inoculum to the soil did not appear to reduce A. ostoyae recovery immediately after the fire, but effects appeared after several months. Differences may also be due to the timing (fall or spring) of the prescribed burns. The effects of fire either natural or prescribed on pathogenic and saprophytic fungi may greatly influence infections of woody roots, subsequent disease occurrence, and patterns of tree mortality