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Fungal degradation of wood treated with metal-based preservatives. Part 2: Redox states of chromium
1996 - IRG/WP 96-10164
Concerns have arisen about the leaching of heavy metals from wood treated with metal-based preservatives, such as chromated copper arsenate (CCA). Of particular concern is the toxic redox state of chromium and arsenic in aging and decayed CCA-treated wood. Generally, hexavalent chromium is more toxic than trivalent chromium and trivalent arsenic is more toxic than pentavalent arsenic. The desired outcome from treating wood with CCA is total change of Cr(VI) to Cr(III) and As(III) to As(V). As part of an on-going study to determine the fate of copper, chromium and arsenic during aging and decay of CCA-treated wood, we detected Cr(III) and Cr(VI) in situ in CCA-treated southern yellow pine lumber. The redox states of Cr were determined using synchrotron X-ray fluorescence spectroscopy (SXRF). An SXRF microprobe was used to to detect Cr redox states by measuring X-ray absorption near-edge structure (XANES). The ratio of Cr(III) to Cr(VI) was determined (1) on the surface and interior of lumber two years after CCA treatment and (2) in lumber during decay by a CCA-tolerant fungus, Meruliporia incrassata TFFH-294. The XANES spectrum for Cr(VI) has a strong pre-edge feature that is not present in the spectrum for Cr(III). Only the Cr(III) XANES spectrum was detected on the surface and in the interior of the wood, indicating total reduction of Cr(VI). The XANES spectrum for Cr(III) was detected in wood after 12 week decay by Meruliporia incrassata TFFH-294, indicating that the fungus does not oxidize Cr(III) to Cr(VI) during the decay process. We are currently using XANES spectroscopy to detect and map in situ redox states of As in CCA-treated wood.
B Illman, S Bajt, T L Highley


Preliminary study of the fungicidal and structural variability in copper naphthenates and naphthenic acids
1996 - IRG/WP 96-30114
Copper naphthenates, an oil-borne wood preservative listed by the American Wood-Preservers' Association (AWPA), is manufactured by complexing copper(II) with naphthenic acids. Prior to AWPA listing as a wood preservative, field experiments showed that copper naphthenates generally had good stability and were active against wood-destroying organisms. Recently, however, there have been reports of some copper naphthenate-treated poles rapidly failing. One possible explanation for the varying effectiveness could be that the structure, and resulting biological activity, of the naphthenic acids used to make copper naphthenate may vary. To test this hypothesis several naphthenic acids and copper naphenates were obtained and their fungicidal activity against three wood-destroying fungi measured. In addition, the chemical structure of the naphthenic acids were examined by proton- and carbon- NMR. Different activities were observed, especially against a copper-tolerant fungus. Some apparent correlations were seen between the fungicidal activity and chemical structures for the few samples studied.
T Schultz, D D Nicholas, L L Ingram Jr, T H Fisher


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


AAC preservatives: Recent New Zealand and Australian experience
1982 - IRG/WP 3188
This paper outlines the present commercial situation in New Zealand, presents results of current research undertaken at FRI and CSIRO, Division of Building Research (DBR), and comments on parallel research carried out elsewhere. Finally, some general comments are made on the limitations of present technology.
J A Butcher, H Greaves


Test procedure to determine the effect of timber substrate on the effectiveness of different preservatives in sea-wate
1975 - IRG/WP 414
R A Eaton


Collaborative experiments in testing the toxicity of wood preservatives to soft rot fungi
1970 - IRG/WP 25
Eight Institutes from seven countries, Austria, England, France, Germany, Holland, Sweden and Switzerland have collaborated in an attempt to assess the suitability of various laboratory test procedures for acceptance as standard methods of determining the toxicity of wood preservatives to the cellulose-attacking micro-fungi which cause 'soft rot' of wood. Pure culture methods with Chaetomium globosum have been tested together with soil burial methods in which the mixed fungus flora of unsterilised local soils has been used as inoculum. The results obtained with a copper/chrome/arsenate preservative have been presented and discussed. It is concluded that the information available is not yet adequate to permit definition of a reliable standard test method. The work has however demonstrated the unsuitability of Chaetomium globosum as a test organism in pure culture tests on softwood and has given indications that soils low in organic matter content may be most suitable for mixed culture tests.
J G Savory, A F Bravery


Fungicidal and termiticidal effectiveness of alkylammonium compounds
1983 - IRG/WP 3232
This paper is related to effectiveness of several AAC's against wood decay fungi and termites by Japanese standardized test methods.
K Tsunoda, K Nishimoto


Proposed test procedure to determine the effect of timber substrate on the effectiveness of a copper/chrome/arsenic preservative in seawater
1975 - IRG/WP 411
R A Eaton


Proposed degradation pathway for quaternary ammonium compounds by mould fungi
1996 - IRG/WP 96-10166
One group of chemicals that has attracted considerable attention as potential wood preservatives are the quaternary ammonium compounds (QACs). Based upon results of previous research this study confirmed the degradation pathway employed in QAC-tolerant fungi. For this experiment the two dialkylammonium compounds didecyldimethylammonnium chloride and dioctyldimethylammonium chloride were used. QAC-treated wood blocks were inoculated with the tolerant fungi Gliocladium roseum and Verticillium bulbillosum. After incubation the remaining QACs were extracted with acidified acetonitrilic and HPLC was used to quantify and detect the degradation products.
J L Bürgel, J Dubois, J N R Ruddick


Biological effectiveness of ground-contact wood preservatives as determined by field exposure stake tests
1984 - IRG/WP 3297
Field exposure tests conducted on stakes treated with different creosotes, mixtures of creosote and waxy oil as well as different CCA wood preservatives over a period of 25 years, gave the following results: The CCA preservatives provided excellent biological protection to treated stakes, especially against fungal attack. The CCA Type I, currently approved for use under South African conditions is not inferior to the CCA Type II during long-term ground-contact exposure if the active elemental contents and effective retentions are taken into consideration. The creosotes provided good protection against termite attack but showed fairly poor fungal resistance during long-term ground-contact exposure under wet conditions. The addition of waxy oil greatly improved the effectiveness of creosotes against fungal attack. The CCA preservatives proved to be a better overall ground-contact preservative compared with the creosotes.
W E Conradie, A Pizzi


The use of chlorothalonil for protection against mold and sapstain fungi. Part 1: Laboratory evaluation
1989 - IRG/WP 3515
Laboratory screening of chlorothalonil alone and in combination with other fungicides was conducted against six mold and sapstain fungi. The most promising treatments appear to be chlorothalonil supplemented with CCA or copper-8-quinolinolate. Field tests have been implemented.
J A Micales, T L Highley, A L Richter


Standardisation of tests of toxicity of preservatives to soft rot fungi
1978 - IRG/WP 2119
J G Savory


Fungi associated with groundline soft rot decay in copper/chrome/arsenic treated heartwood utility poles of Malaysian hardwoods
1992 - IRG/WP 92-1567
Copper-chrome-arsenic treated heartwood from Malaysian hardwood utility poles in service for 8-23 y at two localities in the wet tropical Peninsula Malaysia were surveyed for soft rot in the ground-contact region. Soft rot decay was detected in all the poles. Isolation studies indicated the ability of a variety of microfungi and basidiomycetes to colonize treated heartwood. Most isolates exhibited variable soft rot ability based on a combination of soft rot tests. A few of the isolates formed soft rot cavities (decay types 1 & 2) and belonged to genera previously found associated with soft rot decay. In particular, isolates of Chaetomium globosum and Phialophora occurred frequently on the surface of sampled poles, while Paecilomyces variotii occurred at all sampling depths from the wood surface. It appeared that soft rotting ability of selected isolates (determined from both mass loss and dilute alkali solubility of degraded native cellulose) was affected by the choice of incubation temperatures.
A H H Wong, R B Pearce, S C Watkinson


An interim report on trials with 'Boliden K33' and 'Celcure A' in water of different salinities in the Baltic Sea and in the UK
1974 - IRG/WP 406
It was felt necessary to undertake field trials using large test samples exposed in natural water of different salinity in order to determine preservative leaching and to assess the degree of biological attack.
R A Eaton, D J Dickinson


The performance of CCA treatment in bamboo against decay fungi
1993 - IRG/WP 93-30027
Samples of culm wall material from young (< 6 month age) and mature (> 3 years age) culms of the bamboo, Phyllostachys virideglaucescens were treated to equivalent% w/w retentions of a CCA preservative. After fixation and leaching the treated samples were exposed to decay by Chaetomium globosum FPRL S70K, Coriolus versicolor FPRL 28A and Coniophora puteana FPRL 11E. Thin section samples of untreated and CCA treated bamboo were also exposed to Chaetomium globosum PPRL S70K for visual assessment of decay. The results indicated that CCA could control all three decay types in the mature culm but, in the young material, no dose response to the treatment was found at%w/w retentions equivalent to those in the mature culm. The results are discussed with respect to the development of bamboo cell walls and suggest a significant role for the presence of lignin in determining CCA effectiveness.
O Sulaiman, R J Murphy


Premature decay of CCA-treated pine posts in horticultural soils - An overview
1984 - IRG/WP 1241
The recent discovery in New Zealand of early decay in CCA-treated pine posts set in horticultural soils led to the establishment of a comprehensive research programme. The objectives and outline of this programme are presented together with an overview of research progress to date. Results suggest that premature decay of CCA-treated timber is restricted to material placed in highly cultivated soils. The wide spectrum of decay organisms present in these soils, together with high soil fertility and ionic status, presents an extremely harsh biological and chemical environment for treated wood. Tentative conclusions are drawn from interim results and the options for overcoming the problem are discussed.
J A Butcher


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


Optimum growth conditions for the metal-tolerant wood decay fungus, Meruliporia incrassata TFFH 294
1999 - IRG/WP 99-50142
There is a worldwide need for alternative methods for the treatment and disposal of CCA-treated waste wood. Illman and Highley (IRG/WP 96-10163) reported the isolation of a unique strain of Meruliporia incrassata (TFFH 294) with tolerance to CCA. The strain is capable of degrading CCA treated waste wood, giving a 40% weight loss in the ASTM soil block test. The strain is an ideal candidate for degrading CCA-treated waste wood, which is accumulating in landfills at a rapid rate. In this study, we report the optimum growth conditions of the fungus, including the effect of chemically defined liquid media, growth temperature, light sensitivity, oxygen requirement and nutrient supplements. The results of a metal-tolerance test and SEM evidence of fungal growth on CCA-treated wood are given to support M. incrassata TFFH 294 tolerance.
V W Yang, B Illman


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


Comparative performance of several ammoniacal copper preservative systems
1997 - IRG/WP 97-30151
The efficacy of several ammoniacal copper-based wood preservative systems was evaluated in this study. The selection of potential co-biocides was based on the results of an agar plate test. Following this, the most promising systems were evaluated in a standard field stake test. Good correlation was found between the agar plate and field stake test results. Of the preservative systems tested, copper/tribromophenol, copper/naphthenic acid, copper/DDAC, and copper/propiconizole were found to be superior against copper tolerant fungi in comparison to the other systems tested after three years of field ground-contact exposure. The performance of copper/benzoic acid was mediocre. Copper/citric acid was ineffective against copper-tolerant fungi, with its performance being no better than copper alone.
D D Nicholas, T Schultz


A serial exposure technique for estimating probable service life of treated timber
1978 - IRG/WP 2111
This paper briefly describes part of our preliminary work aimed at developing a test procedure that culd be adopted as a standard method. A detailed version of the work has been submitted for formal publication. In both papers, the aim is to promote interest in extended laboratory testing of wood preservatives. It is believed that this work may provide the basis of a laboratory test procedure from which predictions of field performance could be made. The results of the experiment showed that (a) decay of treated blocks increased with successive soil-jar exposure, and (b) the progressive increase in decay was greatest in blocks to the lower retention of CCA.
J A Butcher


A light and electron microscopic study of decayed CCA-treated radiata pine (Pinus radiata) wood from a cooling tower
1994 - IRG/WP 94-10056
An inspection of an industrial cooling tower in New Zealand showed surface decay of 12 year old Pinus radiata wood panels treated with CCA preservative to a retention of around 15 kg/m³ of salt. Wood decay micromorphology typical of that caused by soft rot fungi, white rot fungi, &apos;stripy&apos; and &apos;v-shaped&apos; erosion bacteria and cavitation bacteria were all commonly seen using a light microscope (LM). Some evidence of the presence of tunnelling bacteria was also seen but was not as common. Soft rot was largely absent from the wettest regions sampled such as spray-line supports and side panels in close proximity to the spray lines, and erosion bacteria attack was the predominant type in these areas. Transmission electron microscopy (TEM) showed that unusual patterns largely consisting of troughs, depression and granulations in wood cell walls, were in most instances, almost certainly caused by erosion bacteria, but in others, tunnelling bacteria were also present. Several decay patterns seen under light microscope as matrices of fine troughs parallel and perpendicular to the cellulose microfibres were difficult to characterise in terms of previous classification but were also thought to have been caused by erosion bacteria. The distinction made by previous classification between patternms formed by erosion and cavitation bacteria needed to be questioned on the basis of observations made. Whilst the TEM showed that erosion and tunnelling bacteria were often present in close association within the wood cell walls, light microscopy suggested that, in the majority of section examined, all the types seen were clearly seperated by regions of undegraded cell wall. The observations underscore the importance of erosion bacteria in wood decay under the conditions of a cooling tower where in-service timbers are kept constantly wet by the spray from water sprinklers. Also of significance is the great diversity of decay types seen, in particular the presence of cavitation bacteria and white rot fungi has not previously been recorded for high retention CCA treated cooling tower timbers.
A P Singh, R N Wakeling, D R Page


Durability of Bamboos in India against termites and fungi and chemical treatments for its enhancement
2005 - IRG/WP 05-10553
Bamboo is a very important forest resource that benefits the life of people in a myriad ways including meeting the need for structural uses like posts, pole fencing, scaffoldings, house building, etc. Although it is one of the strongest structural material available, often succumbs to fungal decay and biodeterioration by insects (termites and powder post beetles) during storage and usage. Studies were undertaken on the natural durability of some selected bamboo species against termites in the field condition and against decay under accelerated laboratory conditions. Also the efficacy of CCA treatment by two methods of applications and two organosphosphorous, three synthetic pyrethroid insecticides and cashew nut shell liquid (CNSL) were evaluated for enhancing the durability of bamboo against subterranean termites. The studies indicated that the durability of different species varied greatly and flowered bamboos more durable than nonflowered bamboos against termites and fungi. Boucherie process of treatment with CCA was found more effective than sap displacement method. Among the insecticides evaluated Chlorpyriphos was found most effective in enhancing the durability. The findings were discussed in the present communication.
O K Remadevi, R Muthukrishnan, H C Nagaveni, R Sundararaj, G Vijayalakshmi


Microscopic characteristics of microbial attacks of CCA-treated radiata pine wood
1993 - IRG/WP 93-10011
Light and electron microscopic observations were made of CCA-treated radiata timbers, which had been placed in service in a vineyard soil as supporting poles and as part of a house pile, to determine the cause of their deterioration. The house pile had failed in service after between 9 and 13 years and was of particular interest because decay was more severe in deeper regions than at the surface and attack was present up to 750 mm above the groundline. It was clear from transmission electron microscopy (TEM) that the predominant type of attack in the house pile was caused by erosion bacteria. The erosion patterns seen under the light microscope as troughs, pits and shallow depressions in the cell wall were almost certainly caused by erosion bacteria. However it was not entirely clear what had caused degradation patterns seen as fine channels under the light microscope. Soft rot was seen in outer regions of the post at the groundline but was very rarely seen in deeper regions. The vineyard posts had been attacked by tunnelling bacteria and soft rot. These studies demonstrated the importance of using both the light microscope and TEM in evaluating the cause of wood decay.
A P Singh, R N Wakeling


A study of the colonization of wood blocks in a laboratory unsterile soil test
1988 - IRG/WP 2318
CCA treated and untreated beech blocks were exposed to a defined horticultural loam using the method proposed for the collaborative soft rot test in the soft rot sub-group of Working Group Two. At intervals during the incubation wood samples were removed and fungal isolations were made using selective media. Fungi were identified and tested for their cellulolytic ability and their decay capacity in beech in pure culture. Replicate wood samples were examined by microscopy for colonisation and decay.
M T De Troya, S M Gray, D J Dickinson


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