Abstract Two isolates of Chlorociboria aeruginascens (Nyl.) Kanouse incubated axenically on aspen wood blocks resulted in 18% and 32% mass loss after 134 wks (2 yrs 8 mo). Aspen wood decayed by C. aeruginascens contained cavities in the S2 layer of the secondary cell wall, similar to Type I soft rot attack, as well as erosion troughs and overall thinning and erosion of wood cell walls, resembling decay by Type II soft rot fungi. Using a selective medium, basidiomycete fungi were isolated from 9 of 17 samples of wood from a variety of tree species colonized and stained by Chlorociboria sp. (putatively C. aeruginascens) in a mixed hardwood forest from northern North America. Basidiomycete fungi were identified by ITS sequencing and cultural tests and were shown to be predominantly species of common white rot fungi. In axenic decay tests with aspen blocks, basidiomycete isolates caused mass losses in the range of 10%–50% after 26 wks incubation. Decay tests in which a basidiomycete isolate was co-inoculated with an isolate of C. aeruginascens did not differ significantly (p