FIELD TESTING OF WOOD PRESERVATIVES XVIII PERFORMANCE OF BORATE-TREATED WOOD AGAINST SUBTERRANEAN TERMITES

In the mid 1990s, FPInnovations- Forintek Division initiated a study of the termite resistance of borate-treated lumber above ground, protected from rain in Canada, Japan and Hawaii. The material included hemlock and amabilis fir lumber treated with disodium octaborate tetrahydrate (DOT) and chromated copper arsenate (CCA). Reference materials included Hinoki in Japan ammoniacal copper zinc arsenate (ACZA) treated Douglas-fir in Hawaii and western red cedar in Canada. The samples were evaluated annually for termite attack. In Canada all of the treated material was found to be performing equally well, with some pieces showing residual signs of early superficial feeding or cosmetic damage. Attack was moderate on untreated controls. Similar results were found in Japan with the exception of 2 % borate shell treatments with DDAC in which two samples were rated as moderately or severely attacked. In Hawaii, where termite attack was more severe 2 % and 3 % BAE (boric acid equivalent) borate through treatments and ACZA performed better than the others. After ten years, the tests in Japan and Hawaii were terminated. The Hawaii samples, which had suffered the most attack, were examined by Forintek’s CT scanner to determine the extent o