Butylated hydroxytoluene and ethylenediaminetetraacetic acid combined with cedarwood oil as wood treatments for protection from subterranean termites and wood-decaying fungi

The effects of the antioxidant, butylated hydroxytoluene (BHT), and the metal chelator, ethylenediaminetetraacetic acid (EDTA) in combination with cedarwood oil (CWO) were investigated for wood preservation against subterranean termites as well as two species of white-rot decay fungi and two species of brown-rot decay fungi. Vacuum pressure impregnation was used to treat wood blocks. Resistance of the treated wood test blocks was evaluated using a no-choice bioassay for termites and a soil bottle assay wood decay fungi. Eight treatments were tested: H2O only; BHT only; EDTA only; BHT with EDTA; CWO only; CWO with EDTA; CWO with BHT; and CWO with BHT plus EDTA. For termites, the lowest percentage wood mass losses were for the EDTA, BHT, CWO, and CWO/EDTA treatments, all of which were statistically equivalent. Correspondingly, these treatments all had the highest termite mortalities at 100%. The four species of decay fungi were affected differently by the wood treatments; however, overall CWO and EDTA gave the best protection against wood mass loss. The addition of BHT did not decrease mass loss.