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Fumigation as a remedial treatment: A review of North American literature
1983 - IRG/WP 3253
The development of the use of fumigants for eliminating decay in timber and roundwood in North America is reviewed. Initial experiments on oak wilt identified volatile chemicals which eradicated decay in roundwood. Subsequently, extensive experimentation on Douglas-fir poles in service showed that treatment with chloropicrin eliminated internal decay for more than ten years. Vorlex was also quite effective, but Vapam appeared to be much less effective, with decay fungi becoming re-established within ten years of treatment. Studies on other wood species indicated that fumigation could be successfully used to treat resistant species such as western red cedar. Fumigation of glulaminated beams and large timbers with chloropicrin, showed that internal decay could also be eliminated in these products, although wrapping the beam in polyethylene was beneficial for optimization of the treatment. Bioassay techniques have been reported for successful monitoring of fumigant vapor concentrations in treated poles.
J N R Ruddick

Studies on the infestation behaviour of the powder-post beetle Lyctus brunneus (Steph.) and its physical control in the wood yards of the Caspian forests of Iran
1985 - IRG/WP 1271
Lyctus brunneus (Steph.) is a pest which has not been previously thoroughly studied in Iran. It severely attacks Iranian hardwoods, especially those used in wooden houses and that have not been treated. Research work was necessary to determine the natural resistance of the most important timber species in Iran against this insect.
P Niloufari

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

Laboratory fumigations to determine the minimum temperature for methyl bromide eradication of the oak wilt fungus in red oak
1983 - IRG/WP 3243
Laboratory chamber fumigations of naturally-infected ret oak log sections exterminatet the oak wilt fungus in sapwood at temperatures down to 0°C. Only low, sporadic fungus survival was observed when log sections were gassed with methyl bromide at -5°C and aired for 4 da. at 0°C. Lower temperature treatments were not effective even if gas levels or exposure times were increased by 50%.
E L Schmidt

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

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

Traitement curatif des bois en place. Hygiène et sécurité
1990 - IRG/WP 3585
P Huré

Remedial treatment of wood attacked by insects
1981 - IRG/WP 3175
A review is presented of remedial treatments against wood-boring insects in wood in service. Preconditions and fundamental principles of insect control are compared with the control of fungal attack and reasons are given for the fact that remedial treatments against insects are more commonly applied than against fungi. With regard to insect control measures with a simultaneous preventive effectiveness, information is given on preservatives, control measures as well as on testing the effectiveness of preservatives with eradicant action. An evaluation of 40 tests according to EN 22 or DIN 52164 revealed that a mean depth of effectiveness of 15 mm is obtained at mortality rates of 80-84% of Hylotrupes larvae. At a mortality rate of below 75% the mean depth of effectiveness was about 10 mm and above 90% it was about 27 mm. Among the control measures without any preventive effectiveness fumigation and hot-air treatments are referred to. With regard to biological control measures, practical results are not yet available.
H Kühne

Methyl bromide eradication of the oak wilt fungus in logs. Laboratory and field fumigation
1981 - IRG/WP 3168
Concern over accidental introduction of the oak wilt fungus (Ceratocystis fagacearum) into oak-importing nations has prompted a study supported by the U.S. National Lumber Exporter's Assn. to assess the efficacy of methyl bromide fumigation to eradicate the fungus from logs and lumber. Laboratory and field fumigation trials to develop a reliable and realistic treatment were performed on red and white oaks at the University of Minnesota in 1980. Introduction of pure methyl bromide at a rate of 240 g/m³ of space under a polyethylene cover kept in place for 3 days eradicated the fungus from short log sections at temperatures down to 5°C in laboratory chamber fumigations. Outdoor trials using 2.4 m logs with intact bark reduced the fungus isolation frequency to a fractional percentage of untreated controls, but reducing the duration of fumigation to 2 days was not effective.
E L Schmidt, M M Ruetze, D W French

Fumigant movement in Canadian wood species
1984 - IRG/WP 3296
Pole sections prepared from seven Canadian wood species (Thuja plicata, Thuja occidentalis, Pinus contorta, Pinus resinosa, Pinus banksiana, Pseudotsuga menziesii, southern yellow pine) were fumigated with chloropicrin, methylisothiocyanate and Vapam and the rates of fumigant penetration determined. All three fumigants were applied directly into holes bored radially into the pole sections. Analysis for fumigants commenced after a few days at various sampling distances from the treating point. After three months the test was concluded. Methylisothiocyanate, diffused equally well upwards or downwards in the pole section from the point of fumigation in all wood species, and appears to offer the best potential of the three fumigants as a pole treatment in Canada. When applied directly, chloropicrin initially moved quickly but then the diffusion rate slowed somewhat. Upward movement was fastest in eastern white and western red cedar while downward movement was also rapid in southern yellow and red pine. Chloropicrin movement was rated as good in Douglas-fir but poor in jack pine. Diffusion of chloropicrin was severely retarded in lodgepole pine. In general Vapam movement was slow at first, and then increased with time. Diffusion rates for all wood species were similar except for relatively rapid upward movement in red and southern yellow pines.
J N R Ruddick

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

Trials of new treatments for prevention of kiln brownstain of white pine (Pinus strobus)
1995 - IRG/WP 95-30068
White pine (Pinus strobus) often develops a surface brown oxidative stain when kiln dried. Such stain downgrades high quality lumber and is most likely to occur when fresh, unseasoned lumber is stacked during warm weather prior to kiln drying. Use of reducing agents or pH alteration has been successful, but may have some practical limitations for general use. This study attempted to prevent brownstain by killing living parenchyma in logs (an approach highly successful for hardwoods in prevention of enzyme-mediated stain) with methyl bromide. In addition, a new fungicide combination was tested for brownstain control. Fumigation of logs did reduce stain in dried lumber up to 45% but was much less effective than the fungicide dip (10 sec or 1 min at 0.3% a.i.). The fungicide formulation was an improvement over use of sodium thiosulfate and similar to sodium azide in trials at 2 laboratories. This co-biocide system should provide protection against both oxidative and fungal discoloration.
E L Schmidt, E Christopherson, T L Highley, M H Freeman

Fumigation of New Zealand grown western red cedar for export markets
2001 - IRG/WP 01-30262
The objective of this study was to demonstrate that methyl bromide fumigant penetrates into the centre of western red cedar (Thuja plicata L.) timber to meet the standard for export markets. Kiln dried western red cedar was used and a cavity (50x 30 x 13mm3) was prepared into the centre of each sample board (500 x 200 x 26 mm3 thick). An absorbent sachet used in industry for cross checking that the concentration of methyl bromide meets the standard during fumigation of export commodities was then inserted into the cavity. Two sample boards with individual sachets separated by aluminium foil and positioned at 13 mm below the wood surfaces, were then glued together. After curing of the glue, an aluminium tape was used to seal the four edges of the sample to prevent penetration of methyl bromide through the boards' edges. Fumigation was performed for 24 hours in the laboratory and also in a commercial environment using 80g of methyl bromide/m3 of wood prior to the cross checking of sachets. The results of this study demonstrated penetration of methyl bromide into the centre of kiln dried western red cedar (26 mm thick) in sufficient quantity to meet the specification for export to overseas markets.
B Kreber, G Durbin, D Wilson

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

Development of a disinfection treatment for oak logs to be imported from the USA
1984 - IRG/WP 3283
The European veneer industry depends greatly on oak supplies from the USA. To prevent the accidental introduction of the American Oak Wilt Disease (Ceratocystis fagacearum) into the member states of the EC, a disinfection treatment was developed for oak logs under consideration of the technical requirements of veneer production. Laboratory experiments and field trials in Germany and in the USA showed that the pathogenic fungus can be eradicated from commercial size oak logs with attached bark by fumigation with 240 g methyl bromide per m³ applied for 3 days at a temperature of 3°C or above. For post-treatment monitoring of the fumigation a viability test using tetrazolium chloride was found to be suitable.
W Liese, M M Ruetze

Reduction of kiln brown stain in radiata pine lumber after log fumigation with methyl bromide
1997 - IRG/WP 97-30129
Methyl bromide fumigation of freshly felled radiata pine log sections effectively killed living cells in parenchyma to at least 75mm into sapwood. Lumber cut from logs (fumigated and control) stored 1 month outdoors (dry) showed slightly reduced brown stain when kiln dried at conventional temperatures. A more dramatic reduction and elimination of brown stain was noted in lumber cut from fumigated log sections stored for 6 months under water. Brown stain prevention was noted at conventional as well as high temperature kiln drying schedules (up to 120° C). Limited inspection of planed samples did not indicate control of "kiln burn" in the high temperature dried lumber. The mode of action of fumigation in control of brown stain remains to be documented.
E Schmidt, M E Hedley, D R Page, D Cross

Log fumigation prevents enzyme-mediated sapwood discolorations in hardwoods
1993 - IRG/WP 93-10003
Non-microbial sapwood discolorations in hardwood lumber can cause economic loss by degrade of quality. Based on the hypothesis that the enzyme-mediated sapstain may develop in part from byproducts of parenchyma cells in wood, reshly felled logs of red oak (Quercus spp.) and sugar hackberry (Celtis laevigata) were fumigated under a plastic tarp with methyl bromide. Log sections were checked after fumigation using triphenyl tetrazolium dye to confirm death of parenchyma cells. Logs were cut into lumber which was bulk-stacked in warm, humid conditions to promote non-microbial stain in the sapwood. Lumber from those logs untarped or tarped but not fumigated developed heavy levels of sapstain whereas lumber from fumigated logs was free of stain. This novel approach is being investigated for prevention of other non-fungal stain in wood (eg. brown stain in softwood) with inclusion of alternate fumigants.
E L Schmidt, T L Amburgey

Fumigation of red beech in New Zealand for prevention of graystain
2000 - IRG/WP 00-10343
The discoloration of sapwood of red beech (Nothofagus fusca) after drying has been an ongoing problem which may lower value of material for certain applications (such as flooring) by as much as 50%. The dark gray stain noted after the drying and planing of lumber is not prevented by fungicide dips, and is most likely similar to the enzyme-mediated stain noted in a variety of commercial hardwoods. Fumigation of hardwood logs has proven successful in prevention of such non-microbial sapwood discoloration by killing of parenchyma cells presumably preventing buildup of stain and or enzyme precursors. Red beech logs were fumigated in New Zealand with sulfuryl fluoride (as a methyl bromide replacement) and graystain evaluations were done after normal commercial lumber processing. Fumigation of logs prior to drying increased yield of highest-grade materials by 300% (based on comparison to non-fumigated control log sections from the same trees). This increase was only noted for logs cut four weeks prior to fumigation, and older logs did not respond to fumigation. It is thought that in older logs, stain precursors had accumulated to a level sufficient to provide stain on drying despite killing of parenchyma cells. Fungicide dip of green lumber is essential for fumigated materials to control mold and fungal stain.
E L Schmidt, B Kreber

A study on insect pests and preservation of fire-damaged timbers in Da Xing An Ling forest region
1991 - IRG/WP 1499
Investigated insect pest of timbers of Da Xing An Ling forest region by means of sampling inspection. Meanwhile we had researched insects pest situation, regularity occurred and biological nature for fire damaged timbers attacked in the log yard. The results showed that the mainly insect species are small black-marmorated longicorn (Monochamus sutor L). We had eagaged in various small tests of timber preservation such as: underwater storage, brushing, spraying and fumigation. The results showed that the fumigant treatment was successful. By means of medium-sized tests of fumigant treatment many times. We had obtained the ideal fumigant and the amount of treatment as well as period of treatment.
Lu Wenda, Li Jian, Shao Jing Wen, Liu Yixing, Cui Yongzhi

Effect of fumigation with Sulfuryl Difluoride on wood inhabiting fungi, a laboratory test
2006 - IRG/WP 06-30410
Special methods are necessary for the control of wood destroying organisms in the preservation of monuments and historic buildings because of the conservation of their originality and uniqueness. The control of wood destroying organisms can be realized with conventional liquid wood preservatives or alternative methods. One of these methods is the fumigation. One fumigant, which was in the past often used for the control of wood destroying insects and also of wood destroying fungi, was Bromomethane. It is very effective, but also influences the ozone layer. Therefore a substitution of this fumigant became necessary. A potential alternative could be Sulfuryl Difluoride. This research project has investigated the effectiveness of Sulfuryl Difluoride concerning fungal control. The effect of Sulfuryl Difluoride on the viability of the wood inhabiting fungi Serpula lacrymans (Wulfen: Fr.) Schroeter , Coniophora puteana (Schum.: Fr.) P. Karsten, Oligoporus placenta (Fr.) Gilbertson et Ryv., Lentinus lepideus (Fr.) Fr. and Ophiostoma piliferum (Fries:Fries) H. & P. Sydow was examined. The fungi were cultivated on MEA medium and infected wood samples. The cultures were exposed to different concentrations of the fumigant. After treatment regeneration of mycelia were tested visually and by determination of mass loss of the wood samples. The fungal tests exhibited a good effectiveness of Sulfuryl Difluoride against fungal mycelium. The different fungal species were differently sensitive to the fumigation, but the results clearly showed that Sulfuryl Difluoride was effective at reducing and eliminating the fungal activity.
A Pfeffer, W Unger, G Fröba, G Binker

ISPM No. 15 and the Incidence of Wood Pests: Recent Findings, Policy Changes, and Current Knowledge Gaps
2011 - IRG/WP 11-30568
Largely as a result of international trade, hundreds of species of bark- and wood-infesting insects have become established in countries outside their native range. Many of these exotic insects have caused severe economic and environmental impact to urban and forest trees in the receiving countries. Most bark- and wood-infesting insects have been transported to new countries by means of the wood packaging material (WPM) pathway, which includes products such as pallets and crating. The international community responded to the phytosanitary risk posed by untreated WPM by approving ISPM (International Standards for Phytosanitary Measures) No. 15 in 2002 that specifies treatments designed to kill wood pests in WPM used in international trade. In response to new research findings, ISPM 15 was revised in 2006 and 2009. The goal of ISPM 15, as stated in the 2009 revision, is to ‘reduce significantly the risk of introduction and spread of most quarantine pests.’ Since 2002, heat treatment and methyl bromide fumigation have been the only two approved phytosanitary treatments for WPM. New treatments are urgently needed given that the use of methyl bromide is being phased out worldwide. This paper presents background information on (a) ISPM 15, (b) changes that were made to ISPM 15 during each of the two revisions, (c) research highlights from projects that were used to support the revisions, (d) incidence of insects of quarantine significance that were found in WPM during surveys conducted before and after implementation of ISPM 15, and (e) research needs to further improve ISPM 15.
R A Haack, E G Brockerhoff