Effects of heartwood extractive of Terminalia spinosa on wood degradation by fungi

Abstract

Terminalia spinosa species have very high durability and could survive for long while in use, even in areas prone to attack by termites or fungi. Extractives have been found to have different inhibition rates against fungi. Wood extractives play an important role in the natural durability. The objective of this study was to investigate the durability of Terminalia spinosa when exposed to wood decay fungi. Three brown-rot and three white-rot wood decay fungi were screened for their capacity to degrade T. spinosa .Samples were evaluated for decay by weight loss measurements using a modified E7-93 standard (AWPA) for block test method, growth inhibition by solvent extract of T. spinosa was also tested. Brown rot fungi P. placenta and C. puteana caused the highest weight losses of 16% and 15% on heartwood extracted with dichloromethane and acetone, respectively. P. sanguines a member of white rot fungi was the most aggressive in reducing weight by 24% on toluene/ethanol extracted heartwood. The later was comparable to weight loss of P. patula wood which was used as a positive control. All the test fungi species caused negligible weight loss of less than 2% on un-extracted heartwood of T. spinosa implying that extractives in the heartwood played an important role in preventing fungal infestation and hence damage. Efficacy of extracts increased with increase in concentration.