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Movement and persistence of chloropicrin, Vapam, Dazomet and methylisothiocyanate in red and white oak timbers
1992 - IRG/WP 92-3728
This study describes the movement and persistence of four fumigants in sawn red and white oak timbers exposed out of ground contact for 2 years. Chloropicrin moved the furthest from the point of application, and was the most persistent. Vapam was next best, followed by Dazomet. Methylisothiocyanate (MIT), applied as pellets, was not effective, probably because MIT was lost from pellets prior to treatment. The fumigants did not move as far or persist as long in white oak as in red oak. Wrapping the timbers prior to treatment enhanced the distance chloropicrin and Vapam moved in both red and white oak. However, in white oak, persistence of the fumigants was rather poor in both wrapped and unwrapped timbers.
T L Highley


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


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


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


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


Chemical Analysis of Southern Pine Pole Stubs Sixty Months Following Treatment with a Methylisothiocyanate-Based Solid Fumigant Stick
2019 - IRG/WP 19-30740
Methylisothiocyanate-based fumigants have been commercially used in the United States for over 35 years to control internal decay in utility poles and other wooden structures with little technological advancement. The most recently commercialized methylisothiocyanate-based fumigant is chemically known as dazomet. Dazomet is a free-flowing powder or granule that decomposes in the presence of moisture within a utility pole to release methylisothiocyanate. As a means to accelerate the decomposition to methylisothiocyanate, a copper solution can be applied to dazomet during the time of fumigant application. Laboratory and field studies conducted as part of the Utility Pole Research Cooperative at Oregon State University have demonstrated the long-term efficacy of dazomet. Concerns with applicator safety, inefficient copper-dazomet interaction, accurate dosing and a high potential for accidental spills, has led OSU researchers to develop several solid forms of dazomet. While long-term field testing by the OSU-UPRC has generated positive results, the prototype forms of solid dazomet had little commercial value. Recently, a commercially viable solid-stick dazomet product was introduced to the remedial wood preservative market to prevent and arrest active decay within in-service wood utility poles. To demonstrate the long-term performance characteristics of this solid form of dazomet, a field study was established in January 2014 in southern pine utility pole sections. At the fourth inspection conducted 60 months following fumigant treatment, chemical assay borings were removed at various pole heights and depths and analyzed for concentrations of methylisothiocyanate using GCMS. The 60-month results showed the concentrations of methylisothiocyanate were greatest in the pole sections treated with the copper amended solid-stick dazomet. When compared to previous chemical assay results at 12, 32 and 46 months following fumigant treatment, the 60-month results showed a sharp increase in concentrations of methylisothiocyanate in the copper amended solid-stick dazomet treated pole sections. The granular dazomet showed a slight increase in methylisothiocyanate production, where the unamended solid-stick and copper amended granular dazomet showed little change from 46 to 60 months of exposure. When compared to a methylisothiocyanate threshold value for decay fungi proposed by Oregon State University, the chemical assay results at 60 months indicated all fumigant treatments are effectively protecting the zone of fumigant treatment (15.2 cm below to 15.2 cm above groundline) of southern pine pole sections. However, the greatest protection within and above the zone of treatment was provided by the copper amended solid-stick dazomet treatment. Future sampling and chemical analysis of the southern pine pole sections are planned to monitor long term efficacy of the fumigant treatments.
D J Herdman, T Pope, R R Browning