Most screening of potential biocontrol agents of wood decay fungi has previously been undertaken using artificial media. Similarly experiments designed to evaluate the mechanisms involved in antagonism between biological control agents and target fungi, have largely been carried out in conditions which do not accurately reflect the nutrient status of wood. This paper examines the influence of nutrient composition of growth media on the antagonistic responses of Trichoderma spp. against two wood decay basidiomycetes, a brown rot fungus Neolentinus lepideus and a white rot fungus Trametes versicolor. Assessment of individual modes of antagonism were carried out on two media types, a 3% malt extract agar and a nutritionally poorer minimal medium. The outcome of antagonism between Trichoderma isolates and wood decay fungi was often found to be dependent on the media type, while testing of individual modes of antagonism again highlighted the importance of substrate composition. Analysis of variance testing of a range of antagonistic properties showed that: minimal media generally resulted in higher inhibition of white rots by the volatiles, whereas inhibition by soluble metabolites of both basidiomycetes was higher in the malt extract medium. Total activity of lytic enzymes was higher in malt extract, however specific enzyme activity was found to be greater in the minimal medium. Siderophores were produced only in the minimal medium. The significance of the results for selection of appropriate media for screening of biological control agents for wood protection is discussed.

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