Resistance of different age groups of timber of Ailanthus species to biodeterioration in Karnataka conditions

Abstract

Four age groups of two plantation grown species of Ailanthus viz., A. excelsa (Roxb) and A. malabarica DC. were evaluated for their natural resistance against wood decay fungi in laboratory condition and against termites in graveyard condition. The effect of two preservatives, copper–chrome–arsenic (CCA) and copper–chrome–boric (CCB) were also evaluated for their effect as preservative on these timber species. There was significant difference in deterioration among different age groups and between the two species, A. excelsa underwent total destruction by termites within 12 months of exposure irrespective of their ages where as A. malabarica was intact to the tune of 30–50 % at 36 months of exposure. The preservative treated specimens were free from any degradation even after 36 months of exposure. Decay pattern against fungi under laboratory conditions with different age group of timber showed that A.excelsa in all age groups comes under non-resistance class with weight loss between 30 and 45 % whereas A. malabarica in all age groups comes under moderately resistant class with the weight loss between 10 and 29 %. Treatment has given complete protection against decay fungi in both the species.