AbstractInteractions between the two most common decay fungi ofPopulus tremuloides, Peniophora polygoniaandPhellinus tremulaewere studied.Pe. polygoniainhibited the growth ofPh. tremulaewhen grown in paired culture. The presence of a culture ofPe. polygoniareduced the growth ofPh. tremulaein a volatile metabolite test. A culture filtrate ofPe. polygoniareduced the growth ofPh. tremulaein liquid culture. The growth of both the fungi was inhibited, and they formed a dark brown line at contact point when grown on aPo. tremuloidesblock.