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Internal decay is a common problem in poles or timbers of thin sapwood species. Several internal treatments have been developed to arrest this attack, and these systems are widely used in North America. Although these treatments have been evaluated in numerous independent field trials, there is no single test of all treatments. The objective of this study was to assess the chemical distribution and fungal colonization in Douglas-fir poles treated with each of 13 different internal remedial treatments over a 10-year period. Metam sodium treatments provided the shortest protective period, with little evidence of residual chemical 3 years after treatment. Methylisothiocyanate (MITC) in pure form provided a very high initial flush of active ingredient and a longer protective period extending from 5 to 8 years after treatment. Dazomet, which must decompose to produce MITC, took slightly longer to reach effective levels, but was still present at effective levels 10 years after treatment. Chloropicrin, which has strong interactions with wood, was associated with the highest chemical levels after 10 years. Borates took longer to reach effective levels in the poles and their protective zone was narrower than the fumigants, but boron was still present at effective levels 10 years after application. The results illustrate the different properties provided by each treatment, but also show that all tested remedial treatments were effective within certain limitations., Pressure treatment of large timbers and poles of thin sapwood species generally produces a shallow shell of protection surrounding the untreated heartwood core (Graham 1983). The treatment remains protective if [...]

Abstract Routine inspection of wood utility poles to detect internal decay involves drilling holes at or about the ground line. While these holes are useful for detecting internal decay, their [...]

Abstract Red oak, Douglas-fir, and ponderosa pine lumber was treated with a silicon/paraffinic system to assess the ability of the treatment to limit dimensional changes and moisture uptake during changes [...]

Abstract A solid, crystalline fumigant (dazomet) with and without a supplemental copper compound was evaluated as an internal decay control treatment on Douglas-fir poles in two long-term field tests. Methylisothiocyanate [...]

Abstract The potential for migration of boron from wood pressure-treated with disodium octaborate tetrahydrate (DOT) during rainfall events was assessed using sawdust, small blocks, and sections of Douglas-fir boards. Boron [...]

Abstract The residual protective effect of sodium n-methyldithiocarbamate (NaMDC) fumigant was investigated in Douglas-fir timbers in a bridge in western Oregon using fungal colonization and levels of methylisothiocyanate (MITC; the [...]

Abstract The effect of metal end plates on reducing checking of pentachlorophenol-treated Douglas-fir crossarms was evaluated over 13 wet-dry cycles. Check development was variable over the first three to four [...]

Abstract The effect of copper naphthenate treatment on electrical resistance of Douglas-fir utility poles was compared with similar poles either left untreated or treated with pentachlorophenol (penta). Penta-treated and untreated [...]