The effects of specific volatile organic compounds produced by Trichoderma spp. on the growth of wood decay basidiomycetes

Previous work by Srinivasan et nl. (1992) and Bruce et al. (1996) has shown that inhibition of wood decay fungi by volatile organic compounds produced by Trichoderma spp, is dependent on the type of growth media and age of the Trichoderma colony. Wheatley ed al. (1997) identified five volatile organic compounds produced by Trichoderma spp. that may be inhibitory to wood decay fungi. The effects of four of these compounds (Acetone, 2-methyl-1-butanol, heptanal and octanal) were tested over a range of concentrations against four selected wood decay fungi. Fungi were incubated in malt extract broth under appropriate conditions and growth was estimated by biomass production and respiration rates. Growth of all Four fungi was affected by at least one of the compounds, usually by inhibition but occasionally stimulation. All but two of the fungus/chemical combinations showed significant effects on biomass development (P < 0.05) and fifteen of the sixteen combinations produced a significant concentration effect on respiration rates (P < 0.05). The aldehydes, heptanal and octanal, were very effective against all four wood decay fungi. All four fungi were inhibited by more than 80% at 25 mug ml(-1) by heptanal and three of the four fungi were totally inhibited at 250 mug ml(-1). Acetone did not inhibit the four wood decay fungi and even stimulated fungal growth at some concentrations. 2-methyl-1-butanol was only effective at the highest concentration of 2500 mug ml(-1). The implications of these results for the biological control of wood decay fungi and future studies are discussed.