Effect of Cottony Snow Mold on Mortality and Biomass of Calamagrostis canadensis under Controlled-Environment Conditions

A low-temperature basidiomycete (LTB), the causal agent of cottony snow mold, was evaluated as a potential biological control agent for marsh reed grass (Calamagrostis canadensis [Michx.] P. Beauv.), a native grass of the North American boreal forest. Marsh reed grass and 2-year-old white spruce trees (Picea glauca [Moench] Voss) were inoculated with LTB and incubated for 12 weeks in a cold chamber to determine whether the fungus was pathogenic to these species. The fungus was not pathogenic to white spruce but was to marsh reed grass, causing 15% mortality and 64% reduction in dry weight of aboveground plant matter. In a second experiment, two clones of marsh reed grass were inoculated with an isolate of LTB and incubated for 8, 14, and 20 weeks in a cold chamber. Maximum response in the grass to the LTB treatment occurred after 20 weeks of incubation, with decreases of 97, 97, and 63%, respectively, in tiller number, dry weight of aboveground plant matter, and plant height. The LTB is a potential biological control agent of marsh reed grass.