Field Performance of Refractory Softwoods Treated with CA or ACQ after 10 Years of Exposure in Korea and Canada

Abstract

Korean wood preservation standards require deep penetration, which precludes the use of many refractory species. However, such treatments of refractory species have been shown to be effective in other parts of the world. A field test was therefore initiated to evaluate the performance of western hemlock, a moderately refractory species, and white spruce, a highly refractory species, pressure treated with either copper azole or alkaline copper quaternary under Korean field conditions that included both decay and termite hazards. After 10 years of exposure in a ground proximity and field stake test in Jinju, Korea, the treated materials remained largely sound, while untreated controls failed much earlier, largely due to termite attack. These data suggest that material that does not meet current Korean penetration requirements could still provide effective protection against biodegradation under Korean conditions. Decay was more advanced in matched treated stakes exposed at a test site in Canada than at the site in Korea.