Durability of timber of Grevillea robusta (A. Cunn. ex R. Br.) at different ages, grown in dry and wet regions of Karnataka

Abstract

Experiments were conducted as per BIS Standards to assess the natural durability of timber from 5,10,15 and 20 year old trees of silver oak, Grevillea robusta grown in wet and dry regions (high and low rain fall area) of Karnataka, against brown and white rot fungi under laboratory conditions and against termites under soil burial exposures. All the age group timbers from both the regions fell within the resistant to moderately resistant class when tested against decay fungi under laboratory conditions. Timber from 5 year old trees was destroyed completely by termites within 4 years of exposure in test yard. While 10 year samples showed retention between 35 and 50 %, 15 and 20 year timber samples showed good resistance (80–100 %) up to 3 years of exposure. The susceptibility to termite attack reduced as the age of the tree increased. The termite attack was relatively more in the timber obtained from high rain fall area when compared to that of timber obtained from low rain fall area.