The effect of mixed cultures of some microfungi and basidiomycetes on the decay of three tropical timbers

A laboratory investigation of the effect of mixed cultures of tropical isolates of Trichoderma viride, Penicillium sp. or Aspergillus niger (microfungi) and Pleuotus ostreatus or Gloeophyllum sepiarium (basidiomycetes) on the decay of three tropical timbers was undertaken to seek information on biocontrol of wood decay. Growth of the microfungi on wood blocks, followed by sterilization before exposure to basidiomycetes, enhanced attack by the latter. This indicated a reduction in the decay retarding property of the timber extractives since the basidiomycete attack was not enhanced in timbers which had been extracted before initial exposure to microfungi. Decay increased following an inoculation procedure in which A. niger grew alone on wood blocks initially, but later in mixed culture, with basidiomycetes introduced without the intervening sterilization. A reversal of the procedure also increased decay. A similar wood block infestation procedure involving T. viride or Penicillium sp. and basidiomycetes, however, retarded decay. Decay was inhibited in wood blocks inoculated simultaneously with T. viride or Penicillium sp. and basidiomycetes, whilst being enhanced in the case of A. niger/basidiomycetes co-cultures. The potential of Penicillium sp. and T. viride for bioprotection and remedial measures for wood decay by the white-rot P. ostreatus and the brown-rot G. sepiarium is therefore indicated.