The ability of a range of selected wood-rotting basidiomycetes to grow through unsterile forest soil was investigated in a Mason jar test apparatus. None of the white-rot fungi in test were capable of growing through this soil. Four of the brown-rot fungi grew through the soil and decayed water-treated control mini-stakes to the point of failure during 12 weeks of incubation. Based on the results of this study, consideration of prevalence in North America, preservative tolerance, and pattern of growth, one isolate each of two brown-rot fungi were selected to use in the future experiments to ensure the presence of wood-rotting basidiomycetes in the FAST. These were Leucogyrophana. pinastri Findlay 141 and Fibroporia. radiculosa L-7878-Sp. In addition this unsterile soil-jar test method should be worked up to create a laboratory screening test for ground contact wood preservatives where biodegradation and basidiomycete exposure are assured.