A Comparison of Wood Preservatives in Posts in Southern Mississippi: Results from A Half-Decade of Testing

Wood preservatives extend the useful service life of all wooden commodities used above ground and in ground contact. Over 50 years ago, the USDA-Forest Products Lab established tests in a high decay and high termite hazard zone in southern Mississippi. During the last five decades, periodic reports have been issued by researchers located at the USDA-FPL, in Madison, WI, on the efficacy and performance of southern pine fence posts treated with a variety of wood preservatives. Since 1977, no report has been issued by the USDA-FPL on the performance of these various preservatives in southern pine posts. This study was undertaken to evaluate the long-term efficacy of over 50 wood preservatives in southern pine wood in ground contact. This study reassessed the condition of the treated wood posts in southern Mississippi, and statistically calculated the new expected post life span. It was determined that commercial wood preservatives, like pentachlorophenol in oil, creosote, and copper naphthenate in oil, provided excellent protection for posts, with life spans now calculated to exceed 60 years. Surprisingly, creosote and penta treated posts at 75% of the recommended AWPA retention, and Copper Naphthenate at 50% of the required AWPA retention, gave excellent performance in this AWPA Hazard Zone 5 site. Untreated southern pine posts lasted 2 years in this test site.

Mike H. Freeman, Douglas Crawford, Patricia Lebow, James A. Brient

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Updated on Thu, 05 Aug 2021 by SuperUser Account