Nineteen quaternary ammonium compounds, one polymeric biocide, and salts of three amine compounds were screened for effectiveness in preventing decay of <i>Pinus radiata sapwood by three basidiomycete fungi. Salts of dimethyl lauryl amine were the most effective fungicides; the chloride salt prevented decay when used at 0.25 percent a.i. solution strength (a toxic threshold of < 1.6 kg/m). Some quaternary ammonium compounds of the alkyl trimethyl or dialkyl dimethyl type were effective at 0.25 to 0.5 percent a.i. solution strength (toxic threshold 1.6-3.2 kg/m). Most other quaternary ammonium compounds had toxic thresholds in the order of 3.2-6.4 kg/m. -- AATA