Following inoculuation Phanerochaete chrysosporium grew faster across the surface of an agricultural loam soil at 37-degrees-C than when incubated at 25-degrees-C. Starch or peptone, alone or in combination, failed to stimulate growth of the fungus, while the addition of peptone or peptone-plus-starch to soil incubated at 25-degrees-C (but not at 37-degrees-C) stimulated a bacterium antagonistic to P. chrysosporium. The bacterium produced an antifungal agent in vitro, which inhibited the growth of filamentous fungi including P. chrysosporium and the yeast Candida tropicalis. The assumption that the addition of nutrients to soils necessarily stimulates growth and soil colonization by an inoculated fungus is thereby questioned. Soil incubation with a spore suspension of P. chrysosporium caused a 60% reduction in the time taken to completely degrade 56.25 mug of benomyl g-1 soil, and at least a 30%-plus reduction in the time taken to completely degrade higher concentrations. These results are discussed in relation to practical approaches to the bioremediation of benomyl-treated soils.