VIEW ARTICLE

Influence of Various Initial Moisture Contents on Decay of Sitka Spruce and Sweetgum Sapwood by Polyporus versicolor in the Soil-Block Test. Charles A. Peterson, Former Graduate Student, Yale University School of Forestry, New Haven, Connecticut, Present address: Lovelace Clinic, Albuquerque, New Mexico 87108; Ellis B. Cowling, Assistant Professor, Yale University School of Forestry, New Haven, Connecticut, Present address: Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina 27607. Phytopathology 63:235-237. Accepted for publication 18 August 1972. DOI: 10.1094/Phyto-63-235.

Thin wafers of Sitka spruce and sweetgum wood were adjusted to moisture contents of 6, 40, 45, 50, 60, 75, and 116 (spruce) or 122% (sweetgum) and then incubated with Polyporus versicolor in ASTM Standard soil-block chambers for 4 and 8 weeks. Initial moisture content had no effect on rate of decay. Sitka spruce proved highly resistant to decay by P. vesicolor; sweetgum, highly susceptible. Moisture contents of test wafers decreased substantially after 4 weeks, indicating that the atmosphere within the decay chambers was unsaturated. Increases in moisture content above the fiber saturation point apparently resulted from water of metabolism, and water moved into the test wafers through invading fungus mycelium.