The specification, inspection, and remedial treatment of utility poles are addressed. Included are discussions of enhancing specifications for improved performance, techniques for detecting decay and other defects, and chemical treatments available for arresting decay of poles in service.
Naturally durable woods have a variety of commercial uses. Natural resistance to decay has been evaluated in field and laboratory tests of wood from many species, but there are few places where commercial wood users can find comparative assessments of natural durability. In this report, previous studies have been used...
Untreated and preservative-treated fence posts were exposed in soil at a test site near Corvallis, OR. Several species, including western juniper and Osage-orange, showed exceptional natural durability. Preservative treatment generally extended the useful life of the posts, but the degree of protection varied with the chemical and the application method.
Production of hardwood lumber (mostly red alder) has been a small but growing part of the forest products industry in the Pacific Northwest. In laboratory tests, Rodewod® 200 EC plus borax protected alder at nearly all levels tested. Eight other chemicals provided some protection at the highest level tested. Fungal-stain...
Environmental restrictions have induced many sawmills to seek alternatives to pentachlorophenol (penta) or similar chlorinated phenols to control fungal sapstains on green lumber. Five alternative preventives were evaluated against a traditional penta product (Permatox 101) on Douglas-fir, hem-fir, and pine lumber in an accelerated 6-week test on small specimens in...
The Cooperative continues to actively
address a diverse array of issues related to
the effective use of wood utility poles.
The trials to evaluate the effectiveness of
MITC-Fume are now in their seventh year
and continue to show that methylisothiocyanate
(MITC) levels in MITC-Fume
treatments remain higher than comparable
metham...
This seventh annual report outlines our continued progress on each of six
objectives.
Improved fumigants: We continue to evaluate previously established field
tests, which inlicate that chioropicrin continues to protect Douglas-fir poles
after 17 years and piling after 12 years. Vorlex treated poles are being
gradually recolonized by decay fungi,...
Previously established field trials of
MTTC-Fume continue to show that this
chemical remains in Douglas-fir and southern
pine poles at fungitoxic levels 5 years after
treatment. In general, increasing dosages
resulted in higher chemical levels in the poles.
All of the MITC-Fume treatments resulted in
higher residual M1TC levels than...
The eighth annual report details continued progress on each of the five
objectives. In this year's report, Objectives II and III from previous
reports have been combined to reflect the similarity of each effort.
Improved fumigants: The previously established field trials continue to
demonstrate the superior performance of both chioropicrin...
Evaluations of previously established field trials indicate that
chioropicrin and Vorlex continue to provide a diminishing level of protection to
Douglas-fir poles. Tests of solid methylisothiocyanate (MITC), now in their
thirteenth year, indicate that this chemical continues to prevent recolonization
of Douglas-fir poles by decay fungi. MITC appears to provide...
Evaluation of previously established
field trials of remedial internal treatments
demonstrates the continued performance of
chioropicrin, Vorlex, and
methylisothiocyanate (MITC). While the
degree of protection afforded by these
treatments has declined with time, residual
fungitoxic levels remain in many tests.
Field trials of gelatin encapsulated MITC
indicate that gelatin had...
Evaluations of previously established field trials indicate that
chioropicrin, and Vorlex continue to provide protection to Douglas-fir poles,
although the degree of protection is diminishing. Reapplication of Vapam 18
years after the initial application eliminated fungi which had recolonized the
poles. Methylisothiocyanate (MITC) continues to protect Douglas-fir poles 12
years...
Evaluations of previously established field trials indicate that
chioropicrin, and Vorlex continue to provide protection to Douglas-fir poles,
although the degree of protection is diminishing. Reapplication of Vapam 18
years after the initial application eliminated fungi which had recolonized the
poles. Methylisothiocyanate (MITC) continues to protect Douglas-fir poles 12
years...
Evaluation of previously established
field trials of internal remedial treatments
continues to verify the excellent long-term
protection afforded by these treatments.
Field trials with gell encapsulated
methylisothiocyanate (MITC) demonstrate
that gelatin does not interfere with
chemical release, nor is addition of
supplemental moisture required for release.
Field trials have been...
An aging electricity distribution system and reduced availability of naturally durable tropical hardwoods in Australia will
combine in the next decade to produce a major shortage of poles. One approach to mitigating this shortage is to utilize lower
durability species and improve the penetration of preservatives into the refractory heartwood...
A closed-tube bioassay with Poria placenta was used to measure residual fungistatic vapors in wood fumigated with methylisothiocyanate (MIT). This bioassay showed an inverse linear relationship between fungal growth and the amount of MIT in the wood samples. For fumigated increment-core sections of unseasoned Douglas-fir heartwood (4.8 mm in diameter...
The chemical composition of the boles of 14 Douglas-fir trees growing in the central Willamette Valley of western Oregon was examined to determine whether differences in various chemical component levels might help to explain arthropod or microbial colonization patterns. Levels of nearly all cations as well as N and P...
The effect of various wood characteristics on decomposition of metham sodium to methylisothiocyanate in sixteen North American and Southeast Asian hardwoods and softwoods was investigated. While marked differences were noted in the degree of decomposition among some species, the relationship between decomposition and lignin content, extractive levels, wood pH, or...
Wood that is submerged in fresh water for long periods has increased permeability and other changed properties. Wood that is submerged in salt water may absorb considerable quantities of salts, which may render the wood resistant to microbial colonization. In this report, we describe decay tests on Douglas-fir sapwood and...
Basamid (3,5-dimethyl-l,3,5,2H-tetrahydrothiadiazine-2-thione), a crystalline powder first used as a soil sterilant, has shown promise as a wood fumigant. This chemical decomposes to methylisothiocyanate (MITC), the primary active ingredient, as well as other products; but the rate of decomposition in wood is too slow to be effective unless certain catalysts are...
The levels of copper, chromium, and arsenic in soil surrounding CCA-treated posts and beneath CCA-treated stakes were investigated at a plot near Gainesville, Florida. Metal levels were elevated in soil immediately adjacent to the treated wood, but decreased with distance away or depth. Mean extractable arsenic levels ranged from 1.74...
A small block test was used in assessing whether pelletized sodium n-methyldithiocarbamate (NaMDC) would decompose and produce methylisothiocyanate (MITC) and thereby eliminate Antrodia carbonica colonies from Douglas-fir heartwood. Also evaluated were the effects of wood moisture content, dosage, incubation period, pH level, and presence of copper sulfate on percentage of...
The bioassay with Aspergillus niger is a simple way of determining the presence and amount of pentachlorophenol or tributyltin oxide in wood, but it does not appear useful for measuring strongly fixed chemicals such as chromated copper arsenate, borate, and fluoride. Its effectiveness in detecting other preservatives has not been...
Impact bending and breaking radius were used to measure loss in toughness caused by basidiomycetes isolated from wood. Small test pieces were used to accelerate testing. Wide differences were found among, and sometimes within, the 26 species tested. Brown-rot fungi tended to cause greater losses than white-rot fungi, but no...
Hyphal fragments and protoplasts of two wood-degrading fungi, Postia placenta and Trametes versicolor, were used to examine the effects of two fungicides, copper sulfate and azaconazole, on fungal health (as measured by oxygen consumption, glucose utilization, potassium levels, cell regeneration, and copper uptake). Although both cell systems responded to the...
The influence of moisture content (MC) and conventional preservative treatment on methylisothiocyanate (MIT) sorption and diffusion were investigated in Douglas-fir wood. In wood at 0% MC, the ratio of equilibrium MIT adsorption to desorption concentrations was low (0.2), but it increased rapidly to about 0.94 above 18% MC. Partition coefficients...
The heartwood of western redcedar (Thuja plicuta) is known for its natural resistance to fungal attack, but some users of western redcedar utility poles have suggested that its durability may be diminished as suppliers begin to harvest trees from younger stands. The decay resistance of western redcedar samples from the...
This study evaluated the effects of pretreatment incising of dry lumber and preservative treatment on the shear strength of 1980 pieces of 2 X 4 dimension lumber (nominal 50 mm X 100 mm X 3.6 m long). Three species groups (Douglas-fir, Hem-Fir. and Spruce-Pine-Fir-South) and two commercially produced machine-stress-rated grades...
The fungitoxicity of carbon disulfide (CS2), methylisothiocyanate (MITC), or a mixture of these two gases, to selected wood-degrading fungi was studied by using a fumigation apparatus. Both gases are important decomposition products of metham sodium, the most commonly used fumigant for internal treatment of large wood members. Carbon disulfide (up...
Mylone@ and tridipam are two solid chemicals that decompose to produce methylisothiocyanate (MIT), a highly effective wood fumigant. In this study, two techniques -- a rapid, test-tube method and small-scale, wood-block assay -- were used to determine the effect of the pH of various chemical buffers on the decomposition of...
This study examines the effects of pressure, temperature, and treatment time on supercritical fluid impregnation of such composites as plywood, particleboard, flakeboard, and medium-density fiberboard. Carbon dioxide with methanol as a cosolvent was used as the supercritical fluid, with tebuconazole as the biocide. Biocide distribution, as measured by extraction and...
Heartwood durability of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) was studied as a function of vertical and radial position in boles of trees with a wide range of leaf area/sapwood area ratios. Six 34- year-old trees were harvested from each of three plots established 14 years before: very dense,...
This paper reviews literature on the formation of heartwood and on the components that affect natural durability. It includes discussion about the function of heartwood in living trees, factors influencing the natural durability of heartwood, the process of heartwood formation, and variations in heartwood quantity and quality. Heartwood formation is...
Although boron has many advantages as a wood preservative, this chemical performs poorly in leaching exposures. In this study, we investigated the potential for decreasing the leachability of boron preservatives with polyethylene glycol (PEG). Southern pine (Pinus spp.) test samples impregnated with combinations of sodium borate or boric acid and...
Preservative treatment of whole, wood-based composite products (mainly panels) has disadvantages; problems largely stem from swelling, strength loss, and incomplete or inappropriate penetration during treatment, and distortion during redrying. Pretreatment of comminuted wood prior to mat lay-up is one alternative, though the addition of chemicals may affect bonding during subsequent...
The effect of process variations under supercritical conditions on cyproconazole retention and distribution in ponderosa pine sapwood boards was assessed. While pressure and temperature appeared to affect biocide solubility to some extent, the overall results suggested that biocide movement into wood was influenced more by diffusion than bulk flow. Biocide...
The air permeability of western hemlock from coastal forests in western Oregon was assessed. Permeability varied widely among trees, as well as by position within individual trees. Permeability tended to decrease with distance inward from the bark, a trend implying that this species produces a heartwood zone. These variations may...
The high decay resistance of western redcedar (Thuja plicata Donn) is due to the presence of toxic extractives, called tropolones, in the heartwood. Therefore, tropolone content may be used as an indicator of decay resistance. With increment core-sized samples of western redcedar heartwood, we used gas chromatography to measure tropolone...
This report describes the relationship of incising-induced strength loss in bending as a function of preservative treatment and incising pattern, density, and depth of penetration for various machine stress-rated (MSR) grades of full-size 2 by 4 Douglas-fir, Hem-Fir, and Spruce-Pine-Fir (South) dimension lumber. This study may represent a worst-case "incising...
A small-scale test was developed to evaluate the ability of fungicides to control decay fungi established in wood. The test, which uses blocks 2.5 x 2.5 x 10 cm, tests the ability of a chemical to migrate from the middle of the block to control a previously established decay fungus,...