DIP-DIFFUSION TREATMENT OF RUBBERWOOD LUMBER WITH BORON COMPOUNDS FOR PROTECTION AGAINST POWDER-POST BEETLES INFESTATIONS

Abstract

Investigations were made to study the dip-diffustion treatment of rubberwood (Hevea brasiliensis Muell. Arg.) lumber with boron compounds for protection against powder-post beetles (Heterobostrychus aequalis Waterhouse) infestations. The green rubberwood lumber (av. moisture content 64.80%) and dry rubberwood lumber (av. moisture content 26.99%) sized 4.5x1x22 inches were dipped for two minutes in boron 15% added sodiumpentachlorophenate (NaPCP) 2% and boron 30% added NaPCP 2%. These lumbers were stored under a cover of plastic sheet for 3 days, 6 days and 9 days. The results showed that the green rubberwood dipped in boron 30% with NaPCP 2% and stored for 9 days gave the highest level of both the boron penetration (av. 95.95%) and boric acid equivalent (BAE) content in cross-section and core (av. 0.64% and 0.33% respectively). It also was considered as the most resistant against the attack of powder-post beetles. The green rubberwood dipped in boron 30% with NaPCP 2% and stored in various diffustion storage period (3 days, 6 days and 9 days) obtained the BAE content in the core not less than 0.20% which agree with the dip-diffusion treatment standard of Australia and New Zealand. Efficacy test of boron compounds for the prevention of powder-post beetles indicated that both the concentrations of boron (15% and 30%) could protect rubberwood against H. acqualis infestations.