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The identification and preservative tolerance of species aggregates of Trichoderma isolated from freshly felled timber
1992 - IRG/WP 92-1553
The surface disfigurement of antisapstain treated timber by preservative-tolerant fungi remains a major problem in stored timber. Identification of a range of isolates of Trichoderma based on microscopic morphological characteristics was found to be imprecise due to the variable nature of this organism. In addition, studies to compare visual (morphological) characteristics of these isolates with their tolerance to the antisapstain compound methylene-bis-thiocyanate (MBT) using minimum inhibition concentration (MIC) tests showed no clear correlations. Isoenzyme electrophoresis was used to investigate the taxonomic relationships between species aggregates of Trichoderma isolated from antisapstain field trials and to identify physiological differences between 30 isolates of Trichoderma which show tolerance to MBT at concentrations ranging from less than 4 ppm to 34 ppm. Results indicate that there is considerable variability in the preservative tolerance of different Trichoderma isolates from particular locality. This highlights the need for field testing of an antisapstain compound in the same locality and under the same conditions in which it will be used in practice.
R J Wallace, R A Eaton, M A Carter, G R Williams

A new concept of oxalic acid biosynthesis in physiology of copper-tolerant brown-rot fungi
2001 - IRG/WP 01-10394
Recently, a wide variety of roles of oxalic acid (oxalate) in wood decay systems have been receiving much attention. Copper tolerance of wood-rotting basidiomycetes has been believed to be due to the detoxification of copper wood preservatives by oxalate produced by these fungi. However, biochemical mechanism of oxalate biosynthesis in relation to physiology of wood-rotting fungi has not been elucidated although two oxalate-forming enzymes, oxaloacetase and glyoxylate dehydrogenase, have been studied in our laboratory. Recently, a new role of glyoxylate cycle in oxalate biosynthesis in wood- rotting fungi has been presented, and the cycle commonly occurred to varying extents among the fungi although they were grown on glucose. Enzymatic analyses showed that isocitrate was cleaved by isocitrate lyase in the glyoxylate cycle rather than oxidized by isocitrate dehydrogenase in tricarboxylic acid (TCA) cycle, and the fungi were found to lack a normal TCA cycle due to the absence of - ketoglutarate dehydrogenase. It is noteworthy that glucose was efficiently converted to oxalate in a theoretical yield of about 80%, accumulating in the culture media of F. palustris. The results further indicate that acetyl-CoA derived from glucose was not completely oxidized to CO2 in TCA cycle but was mainly converted to oxalate with help of the other coupling metabolic cycles, including glyoxylate cycle. Formation of oxalate from several intermediary metabolites using cell-free extracts of F. palustris confirmed that oxalate is also the final product of the metabolic pathway in the in vitro system. Thus, it is proposed as a new concept that most of copper-tolerant brown-rot fungi may acquire the energy by oxidizing glucose to oxalate, i.e. oxalate fermentation expressed in the following equation; Glucose + 5O2 --> 2 Oxalate + 2CO2 + 4H2O.
E Munir, T Hattori, M Shimada

Types of decay observed in CCA-treated pine posts in horticultural situations in New Zealand
1984 - IRG/WP 1226
The few reported failures of 11-12-year-old horticultural posts in New Zealand in 1982 were caused by brown-rot. A subsequent survey of CCA-treated posts in all the major horticultural areas has revealed decay of many posts. A microscopic examination of these posts has shown decay by brown-rot, white-rot, soft-rot and bacteria. Several types of bacterial decay have been observed.
J A Drysdale, M E Hedley

Leaching of the new boron based biocide from coated wood
2001 - IRG/WP 01-30267
We investigated leachability of the new boron based biocide - a complex of an amine and boric acid - from vacuum impregnated spruce wood samples. It was determined by the standard ENV 1250-2 procedure that the new biocide is susceptible to leaching so from the water borne as well as from the ethanol borne boron containing preservative treated wood. Leaching may be retarded by application of surface coatings. The ability of a surface finish to prevent leaching is correlated to its water vapour permeability.
M Petric, M Pavlic, F Cadez

Screening-method for the examination of the resistance against contact-insecticides of Lyctus brunneus Steph. beetles
1981 - IRG/WP 2148
A serie of filter-paper rondelles is treated with different concentrations of an organic insecticide dissolved in aceton. Beetles of Lyctus brunneus are put onto the dry surfaces. During the impact of the poison the knock-down is observed and after a following poisonfree holding, the knock-down and mortality are registred.
E Graf, B Lanz

Detoxification of preservatives: Tri-n-butyltin oxide as a biocide
1982 - IRG/WP 1156
T E Dudley-Brendell, D J Dickinson

Extracellular layers of wood decay fungi and copper tolerance
1983 - IRG/WP 1180
Extracellular layers around the hyphae of brown, white and soft rot fungi have been examined using electron microscopy. These layers were isolated for identification. Particular interest was directed towards the extracellular layers of copper-tolerant soft rot fungi.
D M Francis, L E Leightley

The effect of didecyldimethylammonium chloride on growth of different strains of mould fungus Gliocladium roseum
1995 - IRG/WP 95-10105
The tolerance and degrading ability of different strains of Gliocladium roseum towards didecyldimethylammonium chloride (DDAC) were studied. All four of the strains of Gliocladium roseum were tolerant to DDAC and after their growth on amended malt agar, the retention of DDAC in the medium was reduced.
Yu Zheng, J N R Ruddick

An interim report on studies of the tolerance by Sphaeroma (Crustacea: Isopoda) of CCA-treated timber
1982 - IRG/WP 491
In Papua New Guinea any untreated timber exposed to seawater close to mangrove stands is liable to be attacked in the intertidal zone by the crustaceans Sphaeroma terebrans or Sphaeroma triste. Even CCA-treated timber is sometimes vulnerable. The mouth-parts of these animals are adapted for boring, but whether wood particles are ingested remains to be resolved. Some limbs of Sphaeroma terebrans appear to be adapted for filter-feeding. In both species a portion of the gut, the hepatopancreatic caeca, contains cells in which large quantities of copper are concentrated. Specimens of Sphaeroma terebrans taken from CCA-treated piles had an average of 35 mg copper per gram dry weight of hepatopancreatic caeca: the corresponding figure for Sphaeroma triste was approximately 7 mg/g. Specimens of Sphaeroma terebrans taken from mangroves had much less copper in them than those from treated wood. No such clear-cut difference was evident in the case of Sphaeroma triste. Analyses of CCA-treated piles infested with Sphaeroma showed that Cu, Cr and As levels were high at the surface, but that levels in the interior of the pile had dropped since installation Further studies of Sphaeroma gut function are in progress.
S M Cragg, J D Icely

Copper based water-borne preservatives: The biological performance of wood treated with various formulations
1987 - IRG/WP 3451
Wood samples treated with the various components of CCA preservative singly and in combination were tested against a soft rot organism, a copper tolerant brown rot organism and in soil burial both unleached and after leaching. The results suggest that, of the elements tested, fixed copper is essential for preventing soft rot attack and fixed arsenic is essential for preventing attack by a copper tolerant brown rot organism in leaching environments.
S M Gray, D J Dickinson

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

Variation in Canadian bluestain fungi: Tolerance to DDAC and DOT
1999 - IRG/WP 99-10303
Bluestain in Canadian wood products results in significant and unpredictable losses each year. In order to develop rational methods to eliminate or reduce the sapstain problem, a more complete knowledge of the causal organisms must be gained. This includes a knowledge of the variability in tolerance of different fungal species and strains to commercially used chemicals. In British Columbia, the majority of anti-sapstain chemicals are based upon the quaternary ammonium compound DDAC, either as the sole active ingredient or in formulation with co-biocides such as disodium octaborate tetrahydrate (DOT). Ten strains each of the three most prominent blustain fungi found in Canada (Ophiostoma piceae, Ophiostoma piliferum, and Graphium (species C)) were evaluated for their tolerance to DDAC and DOT. The main findings showed there was little or no variation in the tolerance to the chemicals within the strains of each species tested. In the screening tests it was found that DDAC was less effective in inhibiting fungal growth than DOT. However, further examination revealed that the ineffectiveness of DDAC was due to interactions with the media components - a reminder that care must be taken when evaluating results especially with surfactants such as DDAC. Additional work with other sapstain control chemicals is underway.
J Dubois, A Byrne, J E Clark, A Uzunovic

Biocide Treatments for Wood Composites - A Review
2006 - IRG/WP 06-40323
This paper reviews the biocidal treatment of wood composites. Included are in-process and post-process treatments. Various biocides are covered as are methods of application. Novel treatments and technologies are also presented.
J W Kirkpatrick, H M Barnes

Comparison between the Hylotrupes bajulus strains of different European laboratories
1980 - IRG/WP 1118
In several European countries, wood preservatives of the same formulation are subjected for the quality label to particular tests according to standards established by the CEN. The different laboratories which carry out these tests have had their cultures for many years. The insects are kept in optimal nutritional and climatic conditions and have always mated amongst themselves. On the one hand, eradicant tests made with the same preservative in different laboratories have not always yielded the same results, and on the other hand, the Comitte of European Homologation has been trying to establish a single label for the European Community according to which it will be possible to carry out tests by any national laboratory of the participating countries. If the results are satisfactory, this will enable an approval certificate to be provided for the sale of these products throughout the countries of the Community. It is very important to be certain that the behaviour of insects and the insecticide resistance of the different insect strains are identical. For this, the best test seemed to be the determination of the toxic value of the wood preservatives against Hylotrupes bajulus (Linnaeus) new-hatched larvae, according to the European standard EN 47.
M-M Serment

A behavioral assay for measuring feeding deterrency of a slow-acting biocide, A-9248, against the Formosan subterranean termite (Isoptera: Rhinotermitidae)
1988 - IRG/WP 1366
Concentration-dependent feeding deterrency of a slow-acting compound, A-9248 (diiodomethyl para-tolyl sulfone) was studied in a choice test against the Formosan subterranean termite, Coptotermes formosanus Shiraki. A-9248 was a feeding deterrent at concentrations ³8,000 ppm. Initially, Coptotermes formosanus fed on wood treated with 1,000-6,000 ppm A-9248 but learned to avoid the treatment as a result of ingesting sublethal doses of A-9248. Only those groups exposed to wood treated with <1,000 ppm continued feeding on the treated substrates, and ingestion of these concentrations resulted in 85-100% mortality at the end of the 4-week experiment.
N-Y Su, R H Scheffrahn

Soft rot studies on CCA treated eucalypt power transmission poles
1981 - IRG/WP 1132
Initial results found for sixty CCA treated eucalypt poles, from a soft-rot survey are discussed. Retentions of CCA within above and below ground pole samples were variable. The variation was attributed mostly to biodegradation and effect of soil environment, rather than leaching. Bacterial decay was found in many poles and was severe in some cases. Although found in the presence of soft-rot decay, bacterial attack also dominated in regions of the CCA treated sapwood. Timber suffering such attack was appreciably softened. Extracellular layers have been observed around fungal hyphae from agar cultures and within soft-rot cavities. Fungal isolates were used to produce such polysaccharides. This material was used to observe the effect of addition of copper and quaternary ammonium compound. Solutions of extracellular polysaccharides exhibited some ability to bind copper and remove it from solution. In the presence of a quaternary compound polysaccharide was precipitated from solution.
L E Leightley

International standards and the biocide debate - Potential contribution
2000 - IRG/WP 00-20196
Downstream the European 98/8/EEC directive on biocides, a working party of O.E.C.D. has been developing a tremendous work to put together the background information necessary to assess wood preservative efficacy, environmental and human exposure. Standardization may contribute to those efforts, using traditional experience and methodology. Among them, the hazard classification system may be extended to human beings and their environment, in all situations of uses. While primary exposure to biocides seems to be a matter related to classes of processes, the situation differs with secondary exposure to treated wood, related to use categories: in principle, the doses are already restricted to targets in a given class. Additionally, those uses have been , until now, practically limited to construction products. The first need is to extend the hazard class system to all kinds of biocidal wood preservation and their related uses. A methodology is proposed to get access to biocide concentrations and flows in priority compartments, assessment of intake by non-targets and their ratio to no-effect values in order to quantify safety factors. This route could allow to select further priorities for risk reduction at the pre-marketing stage.
G Ozanne

CCA modifications and their effect on soft rot in hardwoods. Part 2
1983 - IRG/WP 3244
The work outlined in this document is a continuation of that presented in Document No: IRG/WP/3201. The findings described in the previous paper are summarised below: a double treatment of CCB followed by arsenic (CCB+A) is more effective than a double treatment of boron followed by CCA (B+CCA) or a single treatment of CCA, CCB or CCAB in controlling soft-rot due to Chaetomium globosum in birch. CCB+A is as effective as the other formulations in controlling Coniophora puteana and Coriolus versicolor in birch and scots pine. CCB fails to copper tolerant basidiomycetes such as Coniophora puteana (F.P.R.L. 11E). A further investigation into the relative activities of CCA and CCB+A was carried out in a soil-bed using loss in strength and loss in weight as the criteria of decay. At the same time some aspects of the chemical nature of the formulations were examined in an attempt to explain the different performances of the treatments in birch. Amongst these tests, gross chemical analysis of the treated woodblocks and observation of the progressive fixation of the preservatives were the most significant.
S M Gray, D J Dickinson

Effect of soil parameters on biocide depletion: laboratory and field studies of water- and emulsion-borne preservatives
2000 - IRG/WP 00-30234
Two field test sites with different soils were selected. Soil analysis showed that the soil at the two sites had considerable texture, base saturation, acidity, and cation exchange capacity differences. Five sets of field stakes were treated as follows: three with water-borne CCA to about 0.4 pcf (6.4 kgm-3) retention, one with 0.75% DDAC, and one with 0.75% DDAC:0.25% chlorothalonil. The last two sets were treated using oil-in-water emulsions. Samples from all five sets were installed at both field sites. In addition, wood samples which had been co-treated with the five sets of field stakes were installed in a lab environment in fungus cellar tubs using soils from the two sites. All wood samples were defect-free southern yellow pine (SYP) sapwood, with the field stakes measuring 19 x 19 x 457 mm3 and the fungus cellar samples measuring 5 x 19 x 250 mm3. The field samples were exposed for two or three years and the fungus cellar samples for 36 weeks, after which depletion of the various biocides was measured. No consistent pattern in CCA depletions between the two soils were observed in either the fungus cellar or field exposure tests, despite the large chemical and physical differences between the two soils. The fungus cellar method may be useful to conduct relatively rapid depletion studies. The authors also discuss problems with depletion studies, including possible influences by soil, wood, and microorganisms present in the soil.
T Schultz, D D Nicholas, D E Pettry, M G Kim

Susceptibility of CCB treated wood to fungal colonization
2003 - IRG/WP 03-10492
CCB treated wood is generally resistant to all wood decay fungi. However, like CCA impregnated wood, susceptibility of CCB treated wood to copper tolerant fungi have been observed. The ability of various brown rot fungal hyphae to penetrate and overgrow the wood samples was investigated. Samples made of Norway spruce (Picea abies) were impregnated with 5 % CCB solution according to the EN 113 procedure. After conditioning, part of the samples was leached according to the EN 84 method. Small stick of unimpregnated wood (r = 1.5 mm, l = 25 mm) was inserted into a hole, bored in the center of the samples, and after that sealed with epoxy coating. Sterilized, leached and non-leached impregnated and unimpregnated specimens were exposed to two copper-tolerant (Antrodia vaillantii, Leucogyrophana pinastri) and two copper sensitive (Poria monticola, Gloeophyllum trabeum) brown rot fungi for one, two or four weeks. After exposure, the inserted wood pieces were removed from the specimens and put onto nutrient medium in petri dishes. Growth of the hyphae from those wood pieces was then visually determined. Rate of colonization by the fungi were determined by measurement of CO2 production. After that, mass losses of parallel specimens were also determined. The fastest colonization of the unimpregnated specimens was by G. trabeum (one week). On the other hand, no fungal growth could be detected on non-leached CCB impregnated specimens even after four weeks of exposure. However, significantly more intense colonization by the copper tolerant fungi were detected on the leached CCB treated samples.
F Pohleven, U Andoljsek, P Karabegovic, C Tavzes, S A Amartey, M Humar

Long-term efficacy of wood dip-treated with multicomponent biocides
2005 - IRG/WP 05-30379
Biocides designed for prevention of indoor mold growth on wood-based materials need to provide long-term protection under conditions of high humidity. Specimens of kiln-dried southern pine and unseasoned southern pine, aspen, and Douglas-fir were dip-treated with borate-dimethylcocoamine (DMCA) supplemented with voriconazole, thiabendazole, or thujaplicin and evaluated at 4-week intervals for inhibition of three mold fungi, Aspergillus niger, Penicillium chrysogenum, and Trichoderma viride, using the ASTM D4445 mold test. After 8 weeks, all treatments of aspen and Douglas-fir inhibited growth of test fungi, while kiln-dried pine only inhibited A. niger and unseasoned pine only inhibited T. viride despite average chemical retentions in pine up to four-fold greater than those in aspen and Douglas-fir. After 12 weeks, aspen and Douglas-fir treated with the thiabendazole-containing biocide continued to provide protection against growth of the test fungi. The thujaplicin-containing biocide provided partial protection of aspen and Douglas-fir for 12 weeks but failed to protect pine samples beyond 4 weeks. A comparison of tebuconazole, propiconazole, voriconazole, and thiabendazole in the borate-DMCA biocide system showed that thiabendazole and voriconazole provided superior protection against the test fungi, particularly T. viride. We conclude that multicomponent biocides with thiabendazole protect aspen and Douglas-fir against growth of test fungi for at least 12 weeks under the conditions of the ASTM 4445 mold test.
C A Clausen, V W Yang

Determination of absorption, accumulation and transport of copper in mycelium of some wood decay fungi
1999 - IRG/WP 99-10323
Copper compounds are common wood preservatives. However, tolerance of some wood decay fungi to copper compounds has been observed recently. Therefore, we tried to elucidate possible causes of this phenomenon. We investigated uptake, accumulation and secretion of copper in the mycelium of potentially copper tolerant fungi (Antrodia sp.) and non tolerant fungus Trametes versicolor. We observed that potentially tolerant fungi have lower uptake of copper to the mycelium than non tolerant species. They also do not transport copper into the medium. That means that copper tolerance of fungi is probably based on low uptake of copper to the mycelium and not on the active transport from the mycelium to the medium.
F Pohleven, S Breznikar, P Kalan, M Petric

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

Wood preservation using furanones derived from marine algae
2004 - IRG/WP 04-10506
Halogenated furanones that are analogues of natural compounds extracted from the red seaweed Delisea pulchra were examined in the laboratory for activity against termites and decay fungi. The furanones were found to have broad spectrum activity, some with solution strengths of 0.01% controlling Coptotermes acinaciformis in a filter paper trial, while 2% solutions impregnated into Pinus radiata blocks also gave control. Some furanones prevented growth on filter papers by Perenniporia tephropora (white rot) and Coniophora olivacea (brown rot) at 1% solution concentration. In treated P. radiata specimens, one of the furanones prevented decay by P. tephropora and Trametes lilacino-gilva while there was some decay by C. olivacea. When blocks were artificially weathered and leached, fungi were not controlled. Furanones have potential as termiticides for the protection of house framing, while further research is required for protection against decay fungi in exposed leaching environments.
L J Cookson, R de Nys, P Steinberg, N Chew

Accelerated laboratory testing of preservatives on 13 North American wood species
1999 - IRG/WP 99-30201
The ability of selected water and solvent based biocides to protect wood against fungal attack was evaluated on 13 North American wood species using 7 decay fungi in a modified soil block test. Most preservatives were capable of providing protection at their recommended above ground and soil contact use levels. Many decay fungi caused substantial weight losses on blocks treated with chlorothalonil, copper citrate or copper dimethyldithiocarbamate. Most other preservatives performed well against a majority of fungi, but were susceptible to one or two of the test isolates. Aspen was the most difficult of the 13 species to protect against fungal attack. The results illustrate the need to confirm performance of new wood preservatives on the range of wood species to which they will be applied prior to field use.
J J Morrell, C M Freitag

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