Performance of softwood preservative treated stakes after 4 years exposure in-ground to decay fungi and termites in tropical Australia
B M Ahmed (Shiday), J R J French, S R Przewloka, P Vinden, J A Hann, P Blackwell
This field study was based on the 1993 IUFRO method and designed as a graveyard (in-ground) test in the tropical region of the Northern Territory to examine the efficacy of novel preservative formulations developed as alternative protection for softwood timber against decay fungi and termites for Hazard Class 3 and 4. This study was supported by the Forest and Wood Products
Research and Development Corporation (FWPRDC).
Timber specimens 500 (longitudinal) x 50 (tangential) x 25 (radial) mm were cut from the sapwood of fast grown Pinus radiata D. Don and treated with trimethylborate (TMB), sodium octoborate, linseed oil and fipronil in various solvents (toluene, linseed oil and deionised water) using a vacuum/pressure treatment method.
After 4 years in-ground, the solvent control and fipronil (only) treated stakes were slightly attacked by soft rot, brown rot and white rot fungi. Most of the stakes had surface damage only, while few of the solvent controls had severe damage by only decay fungi. There was slight attack on the treated timber by soft rot fungi.
A small number of solvent controls and borate treated stakes were severely attacked by subterranean termites, particularly Coptotermes acinaciformis (Froggatt). The fipronil only or fipronil with borate treated stakes were not attacked.
Keywords: IUFRO in-ground field test, decay fungi, termites, Coptotermes acinaciformis, radiata pine stakes, impregnated, toluene, linseed oil, trimethyl borate, sodium octoborate, fipronil, Hazard Class 3 and 4, Northern Territory