Wood decay by Chlorociboria aeruginascens (Nyl.) Kanouse (Helotiales, Leotiaceae) and associated basidiomycete fungi

• Chlorociboria aeruginascens causes green stain and is associated with decayed wood.
• Five species of white rot fungi were isolated from Chlorociboria-colonized wood.
• C. aeruginascens does not enhance nor inhibit decay by white-rot fungi.
• Light microscopy shows that C. aeruginascens is a weak soft-rot fungus.

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 < 0.05) in mass loss from those caused by the respective basidiomycete alone. Results suggest that decay of wood colonized by C. aeruginascens is principally caused by white rot fungi and is neither enhanced nor inhibited by the presence of C. aeruginascens.