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Long-term effectiveness of fumigants in controlling decay in Douglas fir waterfront timbers
1986 - IRG/WP 3364
The persistence, movement, and effectiveness of chloropicrin and Vapam (sodium N-methyl dithiocarbamate) in large, horizontal Douglas fir timbers were evaluated 7 years after fumigation. Chloropicrin prevented reestablishment of decay fungi; reinvasion occurred in some Vapam-treated timbers. Residual fungistatic effect was detected up to 1.2 m from the fumigation site in chloropicrintreated timbers but not in Vapam-treated timbers.
T L Highley


Preservatives treatment and field test monitoring of spruce pole stock: CCA and fumigant treatments
1990 - IRG/WP 3619
The fumigants trichloronitromethane (chloropicrin) and sodium N-methyldithiocarbamate (SNMDC) were used to treat red spruce pole stock, either CCA treated or untreated, through holes bored through the pole's center. The poles were analyzed for the presence of microorganisms immediately before ground installation and again after installation at a pole test site. Monitoring of fumigant movement in the poles was also performed after one year. Results indicate that both fumigants moved throughout the ground line regions of the poles, although less toxicity to the bioassay fungus was observed in the SNMDC treated poles. Reduced fumigant levels, and more sporadic diffusion was noted in the above ground portions of both chloropicrin and SNMDC treated poles although again chloropicrin exhibited greater toxicity to the bioassay fungus. Despite the variability of fumigant diffusion as determined by bioassay, no decay fungi could be isolated from the treated poles after one year. This was in contrast to high frequency isolation of decay from control poles.
A J Pendlebury, B Goodell


Methods for testing fumigant efficacies against termites
1986 - IRG/WP 1297
Methodologies for testing fumigants against termites are reviewed and factors needed to be taken under consideration for standardization listed. Toxicity should be defined by both direct exposure to the gas and under more practical "barrier" conditions which include test enclosures simulating abiotic surroundings of the termites, i.e. wood, nest material, etc. To observe latent effects, mortality should be recorded periodically after exposure until rates decrease to control levels. Fumigant efficacy should be reported as a function of concentration and exposure time, termed lethal accumulated dose (LAD).
N-Y Su, R H Scheffrahn


The effect of selective additives and conditions on the decomposition of Basamid in Douglas fir heartwood
1992 - IRG/WP 92-3698
Basamid is a solid, powdered chemical used as an agricultural soil fumigant. Decomposition of Basamid isothiocyanate, hydrogen sulfide, methyl amine, and formaldehyde. Basamid has some potential as a wood fumigant, but it decomposes too slowly to be effective. Various additives and conditions were tested for their ability to enhance Basamid decomposition in Douglas-fir heartwood. Higher MC's and temperature, as well as copper sulfate and powdered pH 12 buffer increased decomposition rates with copper increasing the efficiency of breakdown to form MITC.
P G Forsyth, J J Morrell


Chemical Analysis of Southern Pine Pole Stubs Thirty-Nine Months Following Treatment with Three Methylisothiocyanate-Based Fumigants
2004 - IRG/WP 04-30349
Agricultural fumigants have been commercially used in the United States for over 20 years to control internal decay in utility poles and other wooden structures. Of the four fumigants which are currently used in the remedial treatment of utility poles, three are based on methylisothiocyanate (MITC) as being the principal fungitoxic component. Two of these MITC-based fumigants, liquid metham sodium and granular dazomet, chemically decompose within a utility pole to release methylisothiocyanate. The third MITC-based fumigant consists of 97% methylisothiocyanate in a solid melt form. Laboratory and field studies conducted as part of the Cooperative Pole Research Program at Oregon State University have demonstrated the efficacy of all three MITC-based fumigants. However, studies conducted to date have not evaluated the three fumigants under the same experimental conditions. As a result, a field study of the three commercial MITC-based fumigants was established in June, 2000 in southern pine utility pole sections. At the second inspection conducted 39 months following fumigant treatment, chemical assay borings were removed at various pole heights and depths and analyzed for concentrations of MITC using GCMS. The 39 month results showed that MITC concentrations were greatest at all pole heights and core depths in the pole stubs treated with the 97% MITC product. In addition, similar concentrations of MITC were found in the metham sodium and dazomet treated pole stubs. When compared to the corresponding chemical assay results at 13 months following fumigant treatment, the 39 month results showed a sharp increase in concentrations of MITC in the 97% MITC treated pole stubs and a sharp decrease in MITC concentrations in the metham sodium treated pole stubs. MITC concentrations remained relatively unchanged in the dazomet treated pole stubs from 13 to 39 months following fumigant treatment. When compared to a MITC threshold value for decay fungi proposed by Oregon State University, the chemical assay results at 39 months indicated all three fumigants are effectively protecting the zone of fumigant treatment (15.2 cm below to 15.2 cm above groundline) of southern pine pole stubs. However, the greatest protection within and above the zone of treatment was provided by the 97% MITC treatment. Future sampling and chemical analysis of the southern pine pole stubs are planned to monitor long term efficacy of the fumigant treatments.
R J Ziobro, J Fomenko, D J Herdman, J Guzzetta, T Pope


Performance if internal remedial treatments to arrest fungal attack in poles and large timbers
2018 - IRG/WP 18-40834
Internal remedial treatments have been used to arrest internal fungal attack in utility poles and other large timbers. Water diffusible systems and volatile fumigants have both been used for this purpose. While both work, it is important to understand the performance attributes of each system. This paper reviews the literature on both systems and makes recommendations for future research.
J J Morrell


Movement and persistence of Dazomet and pellected methylisothiocyanate in wrapped Douglas fir and southern pine timbers
1991 - IRG/WP 1496
The movement and persistence of Dazomet (tetrahydro-3,5-dimethyl-2 H-1,3,5 thiadiazine-6-thione) and pelleted methylisothiocyanate (MIT) was evaluated in wrapped Douglas-fir and Southern Pine timbers. MIT pellets did not impart a fungistatic effect to any of the timbers. Failure of MIT was probably due to loss of MIT from pellets prior to application. Fungistatic effect of Dazomet was consistently detected at 0.3m from the treatment center but effect beyond this distance was variable. Fungistatic effect was detected at 2 years after Dazomet treatment in Southern Pine but not at 3 years. Fungistatic effect was still present in Douglas-fir timbers at 3 years.
T L Highley


The influence of wood moisture content on the fungitoxicity of methylisothiocyanate in Douglas fir heartwood
1987 - IRG/WP 3430
The fumigant methylisothiocyanate (MIT) effectively controls decay fungi in large wood structures, but the influence of environmental factors on its performance are not well understood. Experiments found wood moisture content to greatly influence the fungitoxicity and sorption of MIT in Douglas fir heartwood. At constant, low MIT vapor concentrations (less than 1 µg/cc air), wood at 10% MC bound 5 times more MIT, but required 4 times the exposure period to control the decay fungus Poria carbonica, than similarly treated wood above the fiber saturation point. Sorption of MIT to wood was strongly influenced by wood moisture content, but was not substantially influenced by the amount of wood decay. Increasing wood moisture content from 10% to 30% during fumigation resulted in a rapid volatilization of previously bound MIT and a dramatic increase in fumigant fungitoxicity. The increased fungitoxicity of MIT in wet wood may help explain why Vapam (a 32% solution of sodium N-methyldithiocarbamate in water), which decomposes to produce MIT, has performed well as a wood fumigant.
A R Zahora, J J Morrell


A laboratory evaluation of the fumigant, sulfuryl fluoride (VikaneR), against the Formosan termite Coptotermes formosanus Shiraki
1982 - IRG/WP 1164
A series of laboratory experiments showed that the fumigant sulfuryl fluoride (VikaneR) was effective against small groups of Coptotermes formosanus Shiraki exposed to the gas directly at temperatures from 20-40°C. At 10°C fumigations failed regardless of initial gas concentration. Very high or total mortality was observed at concentrations of 0.79 cc/L or higher. A second series of experiments was designed to evaluate Vikane's ability to penetrate the carton nest matrix. At 30°C penetration was sufficient to produce high mortality with gas concentrations > 1.06 cc/L. The results suggest that current dosage recommendations for the control of Coptotermes formosanus infestations in structures (4 lbs/1000 cubic feet) are too high and should be reevaluated.
J P La Fage, M Jones, T Lawrence


Effect of fumigant residue in aerated wood blocks on the spore germination of decay fungi
1991 - IRG/WP 2382
Fumigants are increasingly used in several countries for remedial treatments of transmission poles to increase the service life. The present study was initiated primarily to test the remaining toxic effects of spruce (Picea rubra) wood, fumigated with chloropicrin (trichloronitro methane) or MIT (Methyl isothiocyanate) after long period of aeration, on the spore germination of decay fungi. This study indicates that spore germination of decay fungi is more sensitive than mycelia for these fumigants. An assay involving spores could therefore complement the earlier proposed open and closed tube bioassays for assessment of remaining ability to prevent reestablishment of decay fungi in fumigated wood. This assay is sensitive both to bound wood residues contributed by the fumigants as well as to fumigant vapor.
J Bjurman, B Goodell


Preliminary modelling of methylisothiocyanate movement through Douglas fir transmission poles
1988 - IRG/WP 3466
Methylisothiocyanate is a volatile solid that is the active ingredient of several registered and experimental wood fumigants. Information on the sorption and diffusion of this chemical in Douglas-fir heartwood and sapwood was used to develop a two-dimensional model of fumigant movement within a single horizontal cross-section of a transmission pole. The model indicated that dry wood (14% MC) strongly sorbed MIT, which resulted in lower rates of MIT movement. Conversely, it was predicted that wetter wood (22 or 40% MC) held MIT less strongly and had a more rapid rate of chemical movement. In addition, predictions suggest that the presence of an oil-treated peripheral shell had a strong influence on loss of fumigant from the surface of the pole, but had little effect on concentration which developed in the heartwood zone. The results indicate that MIT movement can be effectively modeled. Further studies are underway to account for longitudinal movement of MIT in the model and to simulate extended time periods.
A R Zahora, P E Humphrey, J J Morrell


Effect of wood species on decomposition efficiency of metham sodium
1992 - IRG/WP 92-3699
The effect of wood species and temperature on efficiency of metham sodium (32.1% sodium N-methyldithiocarbamate) decomposition to methylisothiocyanate (MITC) was investigated on 10 hardwoods and 9 conifers over a 144 hour period. Gas chromatographic analyses of headspace samples and ethyl acetate extracts of the wood revealed that decomposition never approached the theoretical decomposition efficiency (40%). Decomposition was generally better with hardwoods and at higher temperatures, although there were exceptions with some species. The results suggest that there is some potential for improving the performance of metham sodium through the use of additives which enhance decomposition efficiency.
J J Morrell


On the effectiveness of fumigants against wood-destroying insects and fungi in wooden cultural property
1993 - IRG/WP 93-10030
Based on a survey of the history of the use of fumigants the actual agents are mentioned in relation to their biogenic effect on wood-destroying insects and fungi as well as their corrosive behavior on cultural property. Furthermore the conditions for the use of reactive fumigants in buildings are discussed. Trials to control wood-destroying insects and fungi by nitrogen and bromomethane are the main aspect. The extermination of larvae of wood-infesting insects depends on the time of diffusion of nitrogen through wood. The mycelium of the tested Basidiomycetes is eradicated by a dose of 25 mg/l bromomethane, but the dose for the tested Ascomycetes has to be more than 50 mg/l bromomethane.
W Unger, A Unger


Ability of chloropicrin, Vorlex, or methylisothiocyante to prevent marine borer attack of Douglas fir piling
1989 - IRG/WP 4153
The preservative-treated shell around Douglas-fir piling is an excellent barrier to attack by marine borers; however, damage to this shell can permit marine borer attack. The feasibility of using fumigants to enhance piling performance was examined by exposing fumigant-treated Douglas-fir sections in marine waters off Newport, OR, or Port Hueneme, CA. The piling were inspected annually and increment cores were removed for chemical assays. Fumigant treatment protected the exposed, untreated wood at the end of the pile for the first year, but marine borer activity generally increased after an additional year of exposure. The fumigants appeared to be most effective against shipworm attack. Chemical levels were generally lowest near the attacked region. Fumigant treatment does not appear to be a long-term solution for preventing marine borer attack of untreated wood exposed during construction or usage; however, the treatment does provide short-term protection and may have some use in ports where a regular maintenance program would insure that damage to treated wood was repaired within one year.
M A Newbill, J J Morrell


Cell wall microdistribution of chloropicrin and methylisothiocyanate in treated spruce
1989 - IRG/WP 3548
Chloropicrin and methylisothiocyanate (MIT) residues were observed using SEM/EDXA and TEM/EDXA in treated spruce wafers that had been exposed to the vapors of the two fumigant preservatives. Chlorinated residues from chloropicrin were found throughout the wood cell wall, even in acetone extracted material. The residues were most heavily concentrated in extractive materials in the rays, but unlike previous work, no preferential binding to the middle lamellae lignin was noted. This could be a reflection of the different wood species used, or because of the SEM techniques used previously. Sulfur residues from MIT were also observed throughout the wood cell wall of wood treated with this fumigant. Preferential binding of MIT residues to the middle lamellae cell corners was noted in the TEM/EDXA analysis of the samples, suggesting possible preferential binding of MIT residues to the lignin component of the middle lamellae.
G F Daniel, B Goodell


Efficacy of fumigants in the eradication of decay fungi implanted in southern pine timbers
1986 - IRG/WP 3365
Southern pine timbers (15.2 cm x 15.2 cm x 4.26 m) were fumigated at midlength to evaluate the effectiveness of the fumigants chloropicrin, Vapam, Diazomet, Busan 40, Vanicide 51, Vanicide TH, sodium bisulfite, and ethanolamine in eradication of decay fungi. The fumigants were introduced into 2.54 cm holes which were closed immediately with rubber stoppers. Movement and persistence of lethal concentrations of the vapors were monitored using eight important wood-decay fungi as the vapor-sensing agents. Residual fumigant in the timbers was determined by a bioassay with Gloeophyllum trabeum. Chloropicrin was the most effective of the eight fumigants. Diazomet was the second most effective followed closely by Vapam. The remaining fumigants were ineffective in eradication of the fungal cultures. Fumigant toxicity was generally greatest during the first 4 months following treatment. None of the fumigants were particularly effective at 0.61 m and 1.22 m from the base of fumigation. Bioassay of wood removed from the timbers 1 year after treatment showed no residual toxicity to Gloeophyllum trabeum. Fumigant efficacy varied between timbers. Movement and longevity of the fumigants in the southern pine timbers was not as great as that observed previously in Douglas fir timbers.
T L Highley, W E Eslyn


Chemical Analysis of Southern Pine Pole Stubs Thirteen Months Following Treatment with Three Methylisothiocyanate Based Commercial Fumigants
2002 - IRG/WP 02-30294
Agricultural fumigants have been commercially used in the United States for over 20 years to control internal decay in utility poles and other wooden structures. Of the four fumigants which are currently used in the remedial treatment of utility poles, three are based on methylisothiocyanate (MITC) as being the principal fungitoxic component. Two of these MITC based fumigants, liquid metham sodium and granular dazomet, chemically decompose within a utility pole to release methylisothiocyanate. The third MITC based fumigant consists of 97% methylisothiocyanate in a solid melt form. Laboratory and field studies conducted as part of the Cooperative Pole Research Program at Oregon State University have demonstrated the efficacy of all three MITC based fumigants. However, studies conducted to date have not evaluated the three fumigants under the same experimental conditions. As a result, a field study of the three commercial MITC based fumigants was established in June, 2000 in pentachlorophenol treated southern pine utility pole sections. At the first inspection conducted 13 months following fumigant treatment, chemical assay borings were removed at various pole heights and depths and analyzed for concentrations of MITC using GCMS. The 13 month results showed the concentrations of MITC were greatest at all pole heights and core depths in the pole stubs treated with the 97% MITC product. In addition, higher concentrations of MITC were found in the metham sodium versus dazomet treated pole stubs. The results of the initial sampling of the southern pine pole stubs are compared to results of the fumigant efficacy studies conducted at Oregon State University. In addition, the chemical assay results are compared to a proposed MITC threshold value based on the results of the Oregon State University fumigant studies. Future sampling and chemical analysis of the southern pine pole stubs are planned.
R J Ziobro, T C Anderson, D J Herdman, J Guzzetta, T Pope


Protection of pile tops using combinations of internal treatments and water shedding caps
1993 - IRG/WP 93-30020
Preservative treatment produces an excellent barrier against fungal, insect, and marine borer attack; however, fabricators often disrupt this barrier during construction, creating avenues for entry of decay agents. This problem is particularly acute in marinas along the coastal United States. Standards recommend the application of a water-shedding cap at the time of installation to prevent pile top decay, but this practice is often ignored because the preservatives are sloppy and difficult to apply. As a result, piles along the cost have a high incidence of top decay. In this report, we describe the results of field trials of a variety of simple capping devices in combination with remedial chemical treatments at a marina located near Newport, Oregon. In general, capping alone significantly reduced the incidence of decay fungi in the piles as did application of remedial chemicals. Combinations of both caps and biocides provided the highest degree of protection.
P Schnieder, M A Newbill, J J Morrell


Effect of wrapping on movement of chloropicrin, Vapam, and Vanicide TH in southern pine timbers
1987 - IRG/WP 3411
Important fungi that decay wood protucts were "inoculated" into nonpressure-treated southern pine timbers as vapor-sensing agents to evaluate the effect of wrapping on the movement and persistence of fungitoxic concentrations of chloropicrin, Vapam, and Vanicide TH in the timbers. Fumigant movement and persistence in the timbers was enhanced by wrapping the timbers in polyethylene after fumigation. Chloropicrin moved fastest and exhibited the highest fungitoxicity at the greatest distance from the treatment center (CL). Almost 100% of fungal cultures implanted into chloropicrin-treated timbers died up to 1.22 m (4 ft) from CL by 4 months after treatment. Vapam was the next best with good fungitoxicity at 0.61 m (2 ft) from CL within 4 months; most cultures were killed at 1.22 m from CL by 8 months. Vanicide TH killed most cultures at 0.30 m (1 ft) from CL by 4 months and at 0.61 m from CL by 8 months. Fungitoxicity of Vanicide TH at 1.22 m from CL was variable. By 12 months, fungitoxicity decreased for all treatments, although chloropicrin and Vapam continued to kill all cultures at 0.30 m from CL. Bioassay of cores extracted from chloropicrin- and Vapam-treated timbers at 12 and 24 months exhibited a fungistatic effect at 0 30, 0.61, and 1.22 m from CL. Cores from Vanicide TH-treated timbers exhibited little fungistatic effect at 12 months but good fungistatic effect up to 0.61 m from CL at 24 months.
T L Highley


The use of fumigants for controlling decay of wood: a review of their efficacy and safety
1989 - IRG/WP 3525
Volatile agricultural chemicals (fumigants) such as chloropicrin (trichloronitromethane) and sodium n-methyldithiocarbamate have been used in the United States for controlling internal decay of large dimension wood products for over 20 years. This usage has been concentrated in the electric utility industry, but fumigants are increasingly applied to protect bridge timbers, marine piling, and even living trees. This document will review the characteristics of fumigants in relation to other available chemicals, particularly the water-soluble pastes that are commonly employed in Europe. Studies to improve the handling safety of fumigants and future research needs will also be addressed.
J J Morrell


Gelatin encapsulated fumigants for wood fumigations: Current research status
1985 - IRG/WP 3336
The fumigants chloropicrin (trichloronitromethane) and methylisothiocyanate (MIT) were encapsulated in gelatin as an alternative to liquid fumigant treatments for control of decay fungi in wooden utility poles. Gelatin-encapsulated MIT was stored for over 2 years under dry conditions without significant fumigant leakage. Gelatin encapsulated MIT and chloropicrin were released from capsules when placed in wood above the fiber-saturation point, although capsules were more permeable to MIT than chloropicrin. In field treatments, the addition of small quantities of water along with capsules was sufficient for fumigant release. Encapsulated MIT and chloropicrin treatments effectively reduced decay fungus populations in Douglas-fir utility poles.
A R Zahora, M E Corden, J J Morrell


Selecting fumigants for treatment of internal decay in wood
1986 - IRG/WP 3370
A number of potential fumigants were screened with respect to their toxicity to decay fungi, (Poria carbonica, and Lentinus lepideus) and their sorption characteristics on Douglas Fir (Pseudotsuga menziesii Mirb. Franco) wood. Wafers of infected wood were exposed to different fumigant concentrations for various times then cultured to determine viability. The lethal concentration X time (ct) factors were determined for each fungus species and fumigant chemical. The "pulse chromatograph technique" was used to determine sorption isotherms for the fumigants to establish the relative degree of interaction between the chemicals and wood. Formaldehyde, chloropicrin (trichloronitromethane), and methylisothiocyanate (MIT) were the most fungitoxic of the chemicals investigated. MIT had the strongest affinity for wood, suggesting that this fumigant should persist longer in treated wood than chloropicrin. The proportion of vapor adsorbed on wood increased greatly with decreasing temperature and was generally higher in decayed wood than in sound wood and in 8% moisture content wood than in dry wood.
P A Cooper


Movement of chloropicrin, Vapam, and methylisothiocyanate in southern pine and Douglas fir timbers
1987 - IRG/WP 3410
Douglas fir and southern pine timbers, 15.2 x 15.2 x 426 cm³ (6-in x 6-in x 14-ft), were "inoculated" with brown-rot and white-rot fungi as vapor-sensing agents to evaluate the movement and distribution of fungitoxic concentrations of chloropicrin, Vapam, and methylisothiocyanate (MIT) over a 20-week period. Residual fumigant in timbers was determined by a bioassay with Gloeophyllum trabeum. The fumigants were introduced into 2.54 cm (1-in) holes at midlength in the timbers. Fumigants diffused throughout the cross-sectional area of both pine and Douglas fir. The brown- and white-rot fungi generally showed similar tolerance to the fumigants. Chloropicrin killed most fungal cultures 0.30 m (1 ft) from the treatment center within 1 week after treatment. Vapam and MIT were effective at 0.30 m by 4 weeks. During the 20-week period, kill of cultures at 0.61 m (2 ft) was quite variable by all fumigants, and almost all cultures 1.22 m (4 ft) from the treatment center survived. Bioassay of cores removed from Vapam-treated timbers showed little residual fungistatic effect beyond 0.30 m. Residual fungistatic effect was detected in MIT- and chloropicrin-treated pine and Douglas fir timbers at 0.61 m.
T L Highley


Use of Internal Remedial Treatment to Extend Wood Life at the Fort Vancouver National Historic Site
2010 - IRG/WP 10-30525
The condition of wood in a reconstructed fur trading fort was assessed over a 30 year period. Poor initial treatment had resulted in the development of extensive early decay. While supplemental treatment with chloropicrin and methylisothiocyanate had arrested the attack, the results suggested that remedial treatments were unable to completely overcome the initial problems associated with treatment. The results show both the value and limitations of using remedial treatments in these applications.
C S Love, C Freitag, J J Morrell


Screening method to test efficacy of fumigants against fungi and preliminary data on the efficacy of sulfuryl fluoride
2014 - IRG/WP 14-20551
Methyl bromide is being phased out and there is an urgent need to find a suitable replacement that is effective in reducing exotic pest establishments via trade in wood products. Efficacy data for established phytosanitary fumigants were mostly developed for arthropods and nematodes, and limited information exists for plant pathogens. Increased interest in developing a fast screening process for fungi has prompted this work. Small scale sulfuryl flouride fumigations were conducted in 10 L chambers at six target concentrations (40-240 mgL-1) at 20 C for 24 h against 23 fungal species. Fungi were grown on barley/grain, which was placed in borosilicate glass tubes covered on both ends with a felt cloth to allow uninhibited gas penetration while minimizing the risk of fungal contamination. This allowed simultaneous testing of numerous species/isolates followed by 100% recovery of controls and without contamination of all other isolates exposed to six target sulfuryl fluoride concentrations. Preliminary data have shown that 13 out of 23 species survived the 240mgL-1 exposure. Additional research is needed to test efficacy against more isolates, and under different temperatures and exposure times before experiments closer to field conditions are conducted.
A Uzunovic, A Mukherjee, R Mack, P Elder, S Myers


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