ISOLATION OF SOME WOOD DECAYING FUNGI AND STREPTOMYCES AND THEIR EFFECTS ON SOME COMMERCIAL TIMBER SPECIES IN SRI LANKA

Abstract

Wood is subject to .utack by wood inhahiting fungi in a variety of environmental situationslrnm the standing tree to the wood product in service. An investigation was carried out tostudy the resistance or five conuncrcial timhcr species namely Rubber (111'1'('11 brasiliensis),Luuumidcll.r (Mcli« rlllhlll) Pine (PiIlIlS raribca). Mahogony (.)11'/1'11'11/0 I)I{/(.,.o/,llylla)andTeak (1""("/(11111 ,~nlllrlls) to lung.il attack.

Four wood decaying fungal species were isolated from naturally infected wood samples,Three species namely Trirodcrma Sfl., Mycrlia stcrilia and Streptomvccs sfI. belonging toDcutcromycot ina subdivision and AspergillI'S sp. belonging to Ascomycotiua subdivisionwere identified. These species were used to assess the initial decay of wood. Out of thelour SI1l'l'ics tested SIU'f)/OIlIH'C.I .III. was the most destructive fungal species.

The wl'i)!ht loss or timber was taken as parameter or decay. Wood species and the fungalxpccicx had a significant effect on the weight loss. The highest weight loss due to fungalattack was caused hy Strcptomvrcs species in all the timber species except in Lunumidcllawhere Trirodcrnia Sf' recorded the highest weight loss.

In Rubber, Lunumidclla and Pinus moisture gain was observed with fungal attack whilemoisture loss was observed in controls. In Mahogany and Teak moisture gain due toIUllgal auack was negligihle. Since these fungi caused a considerable damage at the initialstage or decay they can he grouped as primary decaying fungi in wood.