Incising and site effects on long-term durability of pressure-treated refractory wood species

Abstract

Field data examining the long-term effects of chemical wood preservatives on refractory wood species with abundant heartwood is limited. This study was initiated to determine, by ground contact exposure, the effectiveness of preservativetreated heartwood material comprised of refractory Douglas-fir, Engelmann spruce, or southern pine. The study compared incised and non-incised lumber treated at three retentions with either ammoniacal copper arsenate (ACA) or chromated copper arsenate (CCA) and placed in ground contact at Mississippi and Wisconsin field test sites in 1975 and 1976, respectively. Test stakes were examined and rated for decay at various intervals over a 40-year period. Results indicate that incising improved long-term performance in samples treated at lower preservative retentions, particularly southern pine and Engelmann spruce heartwood treated with CCA. Additionally, unexpected higher levels of decay were noted in some of the treatments at the Wisconsin site compared to the Mississippi site. Several factors that may contribute to these differences will be discussed including soil structure, site topology and drainage, and other microclimatic effects between the two sites. Previous metagenomics studies have shown considerable differences in fungal community composition at these two sites, which may also explain the differences in decay activity at the two sites. Proper exposure site characterization is often overlooked as an important consideration when performing long-term field testing.

Citation

Mankowski, Mark E.; Lebow, Stan; Kirker, Grant. 2018. Incising and site effects on long-term durability of pressure-treated refractory wood species. In: McCown, C.; Branton, K., eds. Proceedings, one hundred fourteenth annual meeting of the American wood protection association. Birmingham, AL: American Wood Protection Association: 138-148.