BIOLOGICAL-CONTROL OF WOOD DECAY IN AN OPEN TROPICAL ENVIRONMENT WITHPENICILLIUM SP. AND TRICHODERMA-VIRIDE

The ability of Penicillium sp. and Trichoderma viride to retard the de cay of obeche (Triplochiton scleroxylon) wood in the field for 11 mont hs (January-November) covering dry and wet seasons in a tropical envir onment was investigated using the 'graveyard' method. Inoculation of s takes with Gloeophyllum sp. or G. sepiarium (decay fungi) 24h after tr eatment with T. viride or Penicillium sp. in January (dry season) did not increase decay after 11 months. Total inhibition of the decay fung i was indicated since the low weight losses of stakes was not markedly different from losses in control stakes biologically treated but not exposed to decay fungi. Inhibition of the activities of other unidenti fied field fungi was also indicated because weight losses were greater in uninoculated and untreated stakes. However, decay occurred in stak es biologically treated in January but later exposed to decay fungi in May, after the dry season. A repeat application of T. viride treatmen t in May, to stakes earlier treated in January, markedly reduced decay following exposure to decay fungi in September (wet season). A simila r Penicillium sp. application was not as effective as T. viride applic ation because unlike the T. viride protected stakes, decay was greater in stakes twice protected with Penicillium sp. but not exposed to dec ay fungi. The results indicate that repeated application of biocontrol agents may be important for controlling wood decay following the adve rse effect of the dry season. (C) 1997 Published by Elsevier Science L imited.