IRG Documents Database and Compendium


Search and Download IRG Documents:



Between and , sort by


Displaying your search results

Your search resulted in 77 documents. Displaying 25 entries per page.


Laboratory tests on light organic solvent preservatives for use in Australia. - Part 6: Soft rot resistance of three fully formulated preservatives on different timber substrates
2000 - IRG/WP 00-30245
The above-ground soft rot resistance of substrates treated with three fully formulated light organic solvent preservatives (Cuprivac Green WR, Impresol WR 205 and Vacsol) was studied using a modified vermiculite burial method. The substrates were sapwood of Pinus elliottii and P. radiata and heartwood of Eucalyptus regnans, Pseudotsuga menziesii, Shorea sp. (a lower and a higher density source) and Thuja plicata. Following artificial weathering, replicate test blocks were exposed to either Chaetomium globosum or Lecythophora mutabilis. C. globosum caused 3% or more mass loss of the water and solvent (white spirit) impregnated controls of all three hardwoods and two of the four softwoods, whereas L. mutabilis caused similar attack in only E. regnans and P. radiata. The P. menziesii and T. plicata heartwoods were naturally durable to both soft rot fungi and, hence, no further conclusions can be drawn. None of the preservatives, at the highest retention tested, protected E. regnans from attack by C. globosum, whereas the highest retentions of both the Cuprivac Green WR and Impresol WR 205 protected all other timbers from this fungus. At the highest retention, the latter preservative was the only one to protect E. regnans from L. mutabilis.
G C Johnson, M A Tighe, J D Thornton


Physical properties of ß-1,4-Xylanase produced by Postia (=Poria) placenta: Implications for the control of brown rot
1987 - IRG/WP 1318
The degradation of hemicelluloses is an early event in wood decay by brown-rot fungi. An understanding of the physical properties of hemicellulases may suggest target mechanisms for the development of new control agents. Endo-b-1,4-xylanase was partially purified by column chromatography from wood decayed by Postia (= Poria) placenta. The enzyme was extremely resistant to denaturing conditions; no loss of activity was detected after 2 h in 9 M urea or 6 M guanidine-HCl. Boiling the enzyme for 5 min in 2.5% SDS + 0.5% b-mercaptoethanol reduced its activity by 65%, as measured by the production of reducing sugars. The activity of a-D-galactosidase, another enzyme detected in large quantities in the decayed wood, was reduced by 98% under these conditions. Optimum pH and temperature ranges were pH 2-6 and 50-60°C, respectively. The enzyme appears to be a glycoprotein containing 50-60% carbohydrate (w/w); the carbohydrate moiety may protect the enzyme from adverse environmental conditions. The control of brown rot by in situ inactivation of xylanase may not be feasible because of the enzyme's extreme stability.
J A Micales, F Green III, C A Clausen, T L Highley


Report of Section 1 2003
2003 - IRG/WP 03-10502
F Green III


Treatment of fresh green round bamboos culms (Dendrocalamus strictus) by sap-displacement (wick) method
2005 - IRG/WP 05-40311
Sap displacement method has great potential for treating short length bamboos as it does not require any technical equipment. The process is simple and large nos. of bamboos can be simultaneously treated in relatively short period. There is no wastage of chemicals as the remnant solution reused. Bottom ends and middle portion had better treatment in compared to lop end portion. With increasing length of the flow of preservatives is impaired. The method culms can conveniently 3m length.
R Lal, C N Vani


Analysis of organotin fungicides in wood preservative solutions and double-vacuum treated wood
1983 - IRG/WP 3250
A new analytical method using high-performance thin-layer chromatography (HPTLC), for the assay of organotin compounds in preservative-treated wood, is presented. The organotin compounds are extracted from the ground wood sample with a mixture of hydrochloric acid and ethanol. After HPTLC-separation, exposure of the thin-layer plate to ultraviolet light, and dipping of the plate into a 0.1% pyrocatechol-violet solution, the different organotin compounds are quantitated using a scanning densitometer.
W Hintze, S V Ohlsson


Protection of Ochroma pyramidale from fungal decay with N,N-napthaloylhyroxylamine
1998 - IRG/WP 98-30182
Fungal decay of wood in service results in billions of dollars (U.S.) in losses annually. Recent environmental restrictions, both U.S. and international, are limiting and eliminating the use of broad-spectrum, heavy metal biocides for wood preservation. Restrictions result primarily from problems with disposal. New wood preservatives need to be developed and tested which specifically target key elements in the sequence of fungal decay mechanisms. Our laboratory has been experimenting with chemicals which inhibit pectin hydrolysis during incipient brown-rot and white-rot decay in southern pine sapwood (Inter. Biodeter. Biodegrad. 39:103). In the present paper these results are extended to include the tropical hardwood Ochroma pyramidale (balsa). Balsa blocks (24x18x12mm) were exposed to two brown-rot fungi and one white-rot fungus in ASTM soil block tests for 10 weeks. CCA (6.4 km/m3 ) was compared with the calcium binding agent N,N-napthaloylhydroxylamine (NHA; 1.6, 3.2 & 6.4 km/m3 ) in leached and unleached blocks. CCA protected balsa with minimal weight loss (> 7.4%) with no leaching effects. NHA (6.4 km/m3 ) protected balsa (0.3-1.2%) weight loss but leaching raised the weight losses to 25% with the brown-rot fungus Tyromyces palustris. We conclude that NHA can protect balsa against G. trabeum and T. versicolor with comparable efficiency to CCA (leached and unleached) but not T. palustris.
F Green III, T L Highley


Observations on the penetration of preservatives into green timber
1985 - IRG/WP 3335
Differences in the rate and extent of diffusion of MBT and NaPCP-based preservatives following a short dip treatment were observed. The importance of preservative distribution as well as toxicity to the target organisms in governing the ultimate performance of any anti-sapstain compound is discussed.
G R Williams, R A Eaton, D A Lewis


Oxalic acid production of fifteen brown-rot fungi in copper citrate- treated southern yellow pine
2001 - IRG/WP 01-10388
Non-arsenical copper-based wood preservatives have grown in number since the 1980's as a response to environmental concerns posed by arsenicals. Interest in copper tolerant decay fungi has increased accordingly. Oxalic acid (OA) production by brown-rot fungi has been proposed as one mechanism of copper tolerance. Fifteen brown-rot fungi representing the genera Postia, Wolfiporia, Serpula, Gloeophyllum, Laetiporus, Coniophora, Antrodia, and Tyromyces were evaluated for OA production bi- weekly in southern yellow pine (SYP) blocks treated with 1.2% AI copper citrate (CC). Ten fungi were designated copper tolerant and produced 2 to 17 times more OA in the CC-treated blocks than in untreated SYP after 2 weeks. Weight losses ranged from 20 to 55% in CC-treated SYP after 10 wks. Five fungi were copper-sensitive, producing low levels of OA and low weight losses on CC-treated blocks. In this study, early induction of OA appears to closely correlate with copper tolerance. We conclude that brown-rot fungi able to exceed and maintain an OA concentration of >400 mM in this study effectively decayed SYP treated with copper citrate.
F Green III, C A Clausen


Inhibition of wood decay and termite damage by calcium precipitation
1996 - IRG/WP 96-30111
Fungal decay of wood in service, especially brown rot, results in billions of dollars (US) of losses annually. Recent environmental restrictions, both U.S. and international, are limiting or eliminating the use of broad spectrum biocides for wood preservation, primarily due to problems with disposal. In order to design new, environmentally benign methods for control of wood decay fungi, it is essential to understand the precise sequence of biochemical events as wood is colonized. The production of polygalacturonase (PG) and hydrolysis of bordered pit membranes during incipient brown-rot decay has recently been described by our laboratory. One key to pectin hydrolysis by plant pathogens has been shown to be fungal production of oxalic acid which lowers the pH of the substrate and chelates calcium ions. Production of oxalic acid may serve a similar role during incipient wood decay as calcium oxalate has been visualized by scanning electron microscopy during both brown-rot and white-rot decay. Therefore, it was hypothesized that in situ precipitation of existing calcium ions in wood may prevent the cascade of biochemical events involved in colonization of wood by brown-rot fungi, expecially hydrolysis of bordered pit membranes. Preliminary experiments in our laboratory have shown that brown-rot fungi, white-rot fungi, and termites are inhibited from effecting weight loss of wood following pretreatment of wood blocks with the selective water soluble calcium precipitating agent N,N-naphthaloylhydroxylamine (NHA).
F Green III, T A Kuster, L Ferge, T L Highley


Inhibition of termite damage by N'N-napthaloylhydroxyamine (NHA): Reticulotermes flavipes (Kollar) vs. Coptotermes formosanus Shiraki
2000 - IRG/WP 00-10354
The calcium precipitating agent NHA has been shown to protect southern yellow pine (SYP) from wood decay and termite damage comparable to CCA in field tests (Gulfport, MS) for two years (Crawford and Green, 1999). In a collaborative study, SYP wood blocks were vacuum treated with three concentrations of aqueous NHA and exposed in a no-choice test to Eastern subterranean termites (FPL, USA) and Formosan subterranean termites (WRI, Japan) to determine protection against termite damage. Individual blocks (leached and unleached) were exposed to R. flavipes (AWPA) or C. formosanus (JWPA) for 3-4 weeks. Mean weight loss of wood blocks after termite exposure ranged from 0.0 to 18.0% for R. flavipes and 6.0 to 20% for C. formosanus. Wood blocks exposed to R. flavipes were completely protected by 0.5 and 1.0% NHA, but weight loss in similar blocks challenged by C. formosanus were 6.0% and 6.2% respectively at the same concentrations. NHA acted as an effective termiticide for R. flavipes with 100% mortality after 3 weeks, but only soldiers were preferentially killed in C. formosanus. Formosan subterranean termite workers showed enhanced resistance to NHA treatment when compared to Eastern subterranean termites.
F Green III, S T Lebow, T Yoshimura


Treatability problems - Relationships between anatomy, chemical composition and treatability
2001 - IRG/WP 01-40213
This report documents the results of phase 1 and 2 of a 3-phase research program. In phase 1, two hundred and fifty-six (256) Southern pine (pinus spp.) nominal 2 x 6's (38 mm x 140 mm) from a single mill in Georgia (southeastern US) were evaluated for treatability with CCA preservative. After treatment, 128 pieces representing a broad range of treatment characteristics were selected and more fully evaluated for anatomical and chemical composition. No direct correlation was noted between CCA treatability and any of the anatomical characteristics evaluated in this study. Neither did a direct correlation between chemical composition and treatability seem to exist. The pit tori of all pits evaluated in this study were aspirated against the pit wall for this difficult to treat Southern pine lumber. This pit aspiration might have resulted from pre-treatment kiln drying. Later reductions in kiln temperature and increased kiln humidity (i.e., lowered wet-bulb depression temperature) reportedly resulted in improved treatability. In Phase 2, a methodology was developed to assess treatability after 3 treating schedules and then compare those results to permeability measurements and anatomical characteristics of matched material from 7 growth regions.
J E Winandy, F Green III, D Keefe


Evaluating the natural durability of native and tropical wood species against Reticulitermes flavip
2004 - IRG/WP 04-10539
Environmental pressures to eliminate arsenate from wood preservatives has resulted in voluntary removal of CCA for residential applications in the United States. A new generation of copper organic preservatives has been formulated to replace CCA for decking and in-ground applications but there is no guarantee that these preservatives represent a permanent solution to all related problems. Therefore, it is still necessary to evaluate alternative treatments, as well as naturally durable wood species, in order to be prepared for future changes in the field. In this study, six hardwoods and six softwoods have been evaluated for their ability to resist termite damage by Reticulitermes flavipes in a 4-week laboratory no-choice test. In addition, moderately resistant Douglas-fir and southern pine wood blocks were evaluated after treatment with copper borate, copper naphthanate, and N,N-naphthaloylhydroxylamine (NHA). Erisma, juniper, ipe and white-cedar were shown to be highly resistant. NHA protected Douglas-fir and southern pine as effectively as copper borate or copper naphthanate. These results suggest that some naturally durable wood species, both tropical and native, can inhibit R. flavipes as effectively as preservative treatment.
R A Arango, F Green III, K Hintz, R B Miller


Commercial potential of the four-cycle method for the impregnation of green beech sleepers in Yugoslavia
1975 - IRG/WP 347
This paper was presented to the Conference on Wood Protection held in Sarajevo (Yugoslavia) in 1973. The paper was based partially on the report prepared by J. Struhar and G. F. Franciosi, who were appointed in 1972 as FAO consultants to demonstrate the new impregnation process for green beech sleepers in Yugoslavia. The so-called 4-cycle method was developed at the State Forest Research Institute in Bratislava (Czechoslovakia). The demonstration treatment was carried out at the Kolasin plant, where the double Rueping method is currently used. Comparing the double Rueping method with the 4-cycle method, the author discusses the possibility of introducing the new method into existing impregnation plants in Yugoslavia. Analysis has shown that the production costs of impregnated beech sleepers under the new method would cost 44 Dinars per m³ more for sleepers, or 530,000 Dinars annually (based on the Kolasin plant capacity). On the other hand, formation of tyloses and doat in "white" sleepers during seasoning, estimated to be 10%, would be completely avoided, saving 972,000 Dinars annually at the Kolasin plant. Besides the stock of untreated sleepers would be considerably reduced which would enable the saving of working capital at the Kolasin plant of about 2,5 mill of Dinars. It is also expected that due to higher creosote oil consumption and its even spreading through the wood, the service life of sleepers would be extended by 10 years (from 30 to 40). In such a way the Yugoslavian Railways would decrease the purchasing and installation costs by about 10 Dinars per m³ of sleepers or 1,270,000 Dinars annually (in 1972 USA$ 1 equalled 15 Dinars).
N Vidovic


Application of roller-pressing method to the novel liquid impregnation treatment of green timber
2001 - IRG/WP 01-40198
A transverse compression technique enabled us to impregnate liquid into green timber through replacement of the free water in the timber with a treatment liquid without any critical physical damage to the timber by the roller-pressing method. The roller-pressing is supposed to remove free water the cell cavities and to concurrently introduce the treatment solution into green timber in the treatment vessel. This process seems applicable to the preservative treatment of timber without drying prior to the treatment, and definitely contributes to both the reduction of production costs and the greater yield of the products due to the occurrence of the fewer undesirable checks. When Cryptomeria japonica D. Don was treated with an aqueous solution of phenolic-resin according to this process, weight gain exceeded 40% and anti-swelling efficiency went up to over 60% even for 1 min immersion period after pressing. Further trials are planned to evaluate biological resistance of the treated timber when fungicide(s) and/or termiticide(s) are incorporated into the treatment solution(s).
M Inoue, K Adachi, K Tsunoda, Y Imamura, S Kawai


Serpula lacrymans, The Dry Rot Fungus and its Tolerance towards Copper-based Wood Preservatives
2005 - IRG/WP 05-10555
Serpula lacrymans (Wulfen : Fries) Schröter, the dry rot fungus, is considered the most economically important wood decay fungus in temperate regions of the world i.e. northern Europe, Japan and Australia. Previously copper based wood preservatives were the most commonly used preservatives for pressure treatment of wood for building constructions. Because of a suspicion about tolerance toward copper components, a soil block test was undertaken to clarify the effect of two copper based preservatives, copper citrate and ACQ-D, on the dry rot fungus, Serpula lacrymans compared to an alternative non-copper containing wood preservative. The extensive use of copper-based wood preservatives has hastened the need for understanding why some fungi are able to attack copper-treated wood. The copper tolerance of S. lacrymans and other brown-rot fungi is thought to be due in part to oxalic acid production and accumulation. Oxalic acid has been implicated in copper tolerance by the formation of copper oxalate crystals. Twelve isolates of the dry rot fungus, S. lacrymans and four other brown rot species were evaluated for weight loss on wood treated with 1.2% copper citrate, 0.5% ACQ-D and 0.5% N’N-naphthaloylhydroxylamine (NHA). Eleven out of 12 S. lacrymans were shown to be tolerant towards copper citrate. ACQ-D and NHA, on the other hand, were both effective against the dry rot isolates. These wood preservatives are less toxic toward the environment than traditional copper based preservatives.
A C Steenkjær Hastrup, F Green III, C A Clausen, B Jensen


Transformation of Ophiostoma picea and Trichoderma harzianum with green fluorescent protein (GFP)
2003 - IRG/WP 03-10477
While microbial colonization of wood is presumed to be characterized by a myriad of interactions between numerous organisms, studying these processes is often difficult owing to the opaque nature of the wood and the inability to readily distinguish among the many species colonizing the material. One method for enhancing the ability to distinguish organisms is to induce specific proteins in one or more organisms that can be detected using fluorescence or other light microscopic techniques. The insertion of genes for the production of green fluorescent proteins produced by the jellyfish, Aequora victoria, has been widely used to visualize a variety of organisms. In this report, we describe transformation of two fungi, Ophiostoma picea and Trichoderma harzianum using a green fluorescent protein (SGFP) gene under the control of the ToxA promoter of Pyrenophora tritici-repentis. The growth and wood colonization by two transformed fungi were compared to their non-transformed strains. The expression of gfp was particularly useful for studying the spatial distribution of young hyphae in wood.
Ying Xiao, L M Ciuffetti, J J Morrell


Gas chromatographic determination of 1,8-naphthalimide, N-Hydroxy-1,8-naphthalimide (N,N-naphthaloylhydroxylamine) and the sodium salt of N-Hydroxy-1,8-naphthalimide
2003 - IRG/WP 03-20259
A number of naphthalimide (NI) derivatives are used as efficient laser dyes, in medicine or in scanning electron microscopy. Only N,N-naphthaloylhydroxylamine (NHA) has been shown to be an effective wood preservative against wood decay fungi and termite damage. However, limited information is available concerning the analytical detection of NI-derivatives in treated timber. There is a clear need for the analytical characterisation; e.g. with regard to the penetration depth or the assessment of retention after leaching. This paper describes the development of a gas chromatographic method for determination of NI and their derivatives in timber. These investigations were carried out by means of direct thermal desorption-gas chromatography-mass spectrometry (TD-GS-MS) using the pure substances in solution, as well as direct analysis of treated southern yellow pine (SYP). It was shown that the identification of NHA in treated SYP is possible using this analytical technique. Furthermore first evidence is given for determining quantitative data. Surprisingly, the chromatograms and especially mass spectra obtained for NHA and the sodium salt of NHA are identical to the mass spectra of NI. The first results show that TD-GC-MS can be an option in determining the retention levels of NI and their derivatives in wood.
E Melcher, F Green III


Proposed model for the penetration and decay of wood by the hyphal sheath of the brown-rot fungus Postia placenta
1989 - IRG/WP 1391
Scanning electron microscopy (SEM) of Pinus sp. decayed by the brown-rot fungus Postia placenta confirmed the existence of extracellular membranous structures previously described by transmission electron microscopy (TEM). These structures appear to be an integral part of the hyphal sheath and assume a variety of forms including lamellar sheets, fibrils, and vesicles. These structures were observed (a) on the surface of hyphae, (b) extending from hyphae into the wood surface and covering the S3 layer, (c) embedded in the hyphal sheath and, (d) penetrating into the wood cell wall layers from S3 - S3. We conclude that penetration of the wood cell wall by the complex, multistructured hyphal sheath facilitates the decay process in an orderly and linear progression. The directionality of the decay process appears to alter the fiber orientation of individual wood cell wall layers. This model offers an alternative hypothesis to simple diffusion of wood degrading agents during wood decay by Postia placenta.
F Green III, M J Larsen, L L Murmanis, T L Highley


Early detection of brown-rot decay in southern yellow pine using immunodiagnostic procedures
1990 - IRG/WP 2356
Immunodiagnostic procedures have been used to detect incipient decay of southern yellow pine by six common brown-rot fungi. Rabbit polyclonal antibodies were raised to liquid culture fractions of the six fungi. The antibodies, after preadsorption to sawdust, were tested in particle agglutination assays, immuno-dot blot, and ELISA for their·ability to detect the decay organisms when they were grown in southern yellow pine. Results were correlated to wood block weight loss. Each method specifically detected five of the six test organisms at very low wood block weight loss. Agglutination assays were the least effective and lacked the sensitivity of the other assays, even though the latex particles were more sensitive and reproducible than charcoal particles. Cross-reactivity was only noted for one of the control organisms and only in the charcoal agglutination assay. Both dot blot and ELISA were sensitive test methods, but ELISA had the advantage of quantification. We feel that two of these assays, latex for presumptive results and ELISA for definitive results, could effectively detect incipient decay of common brown-rot fungi.
C A Clausen, F Green III, T L Highley


Steam/hold/APM boron treatment - Treatability trials with green gauged radiata pine
1987 - IRG/WP 3439
Freshly sawn 100 x 50 mm radiata pine was green gauged, steam conditioned and preservative treated with a mixture of borax and boric acid using a modified Alternating Pressure Method (APM) treatment schedule. A 12 hour holding period between steam conditioning and treatment resulted in the necessary moisture loss and moisture re-distribution to facilitate treatment to NZ Timber Preservation Authority preservative retention and distribution requirements.
P Vinden


Protection of southern pine using N,N-Napthaloylhydroxylamine: Field tests, soft-rot cellars and aquatic bioassay leach testing
1999 - IRG/WP 99-30204
Recent environmental restrictions are limiting the use of broad-spectrum biocides for wood preservation. There is an urgent need for new, sharply targeted, environmentally benign wood preservatives. N'N-Napthaloylhydroxylamine (NHA), a water-soluble calcium-precipitating agent, has been shown to inhibit decay by brown-rot and white-rot fungi in soil-block tests and prevent damage by Eastem subterranean termites under lab conditions. In order to further evaluate the capacity of NHA to prevent decay and termite damage, SYP stakes were pressure treated with three concentrations of NHA (0.1, 0.5 and 1.0%) and CCA (1.0%) and placed in-ground at the Harrison Experimental Forest, Gulfport, Mississippi, in June, 1997. Similarly, treated sticks were placed in soft-rot fungal cellars at FPL. One percent NHA-treated stakes were also leached for 72 hours in water and the leachates tested by an acute, five dilution bioassay using Ceriodaphnia dubia in EPA Protocol 600/4-90/27F. Results to date: 1) NHA stakes (0.5 and 1.0%) are as durable as CCA; 2) NHA does not inhibit soft-rot fungi and, 3) NHA is a relatively benign molecule with LD50 130-fold less than copper for C. dubia.
D M Crawford, F Green III


Hemicellulosic induction of oxalic acid in Postia placenta
1994 - IRG/WP 94-10060
Most studies suggest that enzymes produced by brown-rot fungi are too large to penetrate sound wood structures, even after decay begins. Thus, nonenzymatic agents have been proposed to initiate brown-rot decay. We have reported that the brown-rot fungus Postia placenta MAD-698 initiates a 2-fold decrease in wood pH within 7 days of colonization which is mediated by production of oxalic acid. Strain ME-20, essentially a non-decay isolate of Postia placenta, does not accumulate oxalic acid when colonizing wood. Our lab has been investigating potential inducers of oxalic acid production, and we have been comparing hemicellulose-like substrates with cellulose-like substrates in liquid culture. Potent inducers of oxalic acid include xylan, glucomannan, chitin, uronic acids, pectin and compounds containing acetyl sidechains. Although cellobiose also induces oxalic acid in MAD-698, utilization of cellulose is considered a relatively late event, therefore not influencing incipient decay. We conclude that oxalic acid induction is an early event in the decay and is initiated by hemicellulosic substrates and by-products.
F Green III, M Larsen, T L Highley


The long road to understanding brown-rot decay. A view from the ditch
1995 - IRG/WP 95-10101
Interest in understanding how brown-rot fungi decay wood has received increasing interest in recent years because of a need to identify novel targets that can be inhibited for the next generation of antifungal wood preservatives. Brown-rot fungi are unique in that they can degrade holocellulose (cellulose and hemicellulose) in wood without first removing the lignin. Furthermore, they degrade holocellulose in an unusual manner, causing a rapid decrease in degree of polymerization at low weight loss. Despite the increased research effort, the mechanism of brown-rot decay remains unclear and, furthermore, this research has not provided biochemical targets for inhibition and development of new wood preservatives. In viewing the brown-rot literature, it became apparent that many of the beliefs about brown-rot decomposition of wood are based more on tradition or conjecture than on facts. These myths tend to cloud our understanding of brown-rot decay and as a result may contribute to a misdirection of research efforts. The purpose of this paper is to attempt to identify and clarify some of these misconceptions about brown-rot decay that have become dogma.
F Green III, T L Highley


Preservative treatment of green timber by diffusion
1984 - IRG/WP 3291
The preservative treatment of green timber by diffusion is reviewed together with criteria which influence the economics of the process. New process options are described which should overcome some of the technical and economic disadvantages of double diffusion. These include the use of coagulating agents which increase the viscosity of the preservative solution and facilitate treatment by momentary immersion. It is anticipated that the main application for the diffusion treatment process will be for the treatment of refractory timbers for both ground contact and above ground exposure. The system is most suitable for low density and higher heartwood moisture content wood species - for example Sitka spruce, and is ideally suited for use in the tropics for treating both plantation grown softwoods and mixed tropical hardwoods.
P Vinden


Targeted inhibition of wood decay (Using everything but the kitchen sink)
1997 - IRG/WP 97-10203
Low molecular weight oxidative decay agents have been implicated in the degradation of wood by brown-rot decay as evidenced by chemical analysis of brown-rotted wood and detection of oxalic acid and hydroxy radicals. Fenton chemistry (H2O2 / Fe++) is often proposed as the mechanism for generating hydroxy radicals. Previous authors have shown iron to enhance the brown-rot hydrolysis of wood, while others have shown suppression of brown-rot by organic and inorganic metal chelators. We have attempted to inhibit brown-rot and white-rot decay of southern pine and maple wood blocks in a series of soil block decay tests using a variety of chemicals targeted specifically at key components of proposed brown-rot mechanisms. Included in these tests were inorganic and organic chelators, calcium coordinating compounds, wood binding dyes, microbial siderophores and common antioxidants -- some previously tested. All chemicals were screened at 1% aqueous (w/v). Only 2 of 28 compounds were effective in significantly reducing wood weight loss by all fungi tested in 12 weeks: napthaloylhydroxylamine (NHA) -- a calcium precipitating agent; and ruthenium red (RR) -- a pectin stain. Both compounds bind preferentially to pit tori and ray parenchyma cells as observed by light microscopy. Targetting the woody substrate for inhibition of decay looks more promising than targetting fungal physiology
F Green III, T A Kuster, T L Highley


Next Page