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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

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

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

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

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

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

Tolerance of Wood Decay Fungi to Commercial Copper Based Wood Preservatives
2002 - IRG/WP 02-30291
Due to the use of copper based preservatives like CCB or CCA for more than a century, copper tolerant fungi have appeared in some European countries in recent times. It is therefore important to find out whether this phenomenon is specific for only classical copper ingredients, or generally for all copper based formulation. Thus, we tested the tolerance of three commercial copper based preservatives and copper(II) sulphate as well as potassium dichromate for comparison. In this research, seven copper tolerant Antrodia isolates and copper intolerant fungus Gloeophyllum trabeum were tested using a screening test and standard laboratory test SIST EN 113. Screening test were performed on potato dextrose agar (PDA) with copper concentration between 5.0×10-4 and 2.5×10-2 mol/l. The tolerance determined by the screening test was not always comparable with results obtained with the standard laboratory test. However, results obtained on wood samples showed that various fungal isolates exhibited different levels of copper tolerance depending on the copper based biocide. Tolerant strains were able to decay copper sulfate as well as copper naphthenate preserved wood samples. On the other hand, even the most tolerant fungi could not decompose wood preserved with classical CCB or copper amine preservative. It can therefore be concluded that various fungal isolates exhibited different copper tolerance regarding copper formulations. This finding is very important for remediation of waste treated wood by fungi. For a successful detoxification of waste wood impregnated with multi salt preservatives like CCA or CCB the suitable tolerant fungal strains have to be used, simultaneously for synergistic action.
F Pohleven, M Humar, S A Amartey, J Benedik

Influence of acidification on decay processes of CCB treated wood
2004 - IRG/WP 04-10514
The phenomenon of copper tolerance by brown rot fungal strains has been known for a long period but the complete mechanism of copper tolerance by these fungi is not understood yet. Copper tolerance has previously been linked to oxalic acid excreted by copper tolerant brown rot fungal strains. This acid reacts with copper in the wood to form an insoluble and therefore less toxic copper oxalate. There has been a suggestion that copper tolerance had more to do with lowering of the pH of the substrate rather than the low solubility of copper oxalate. In order to elucidate this presumption CCB treated wood samples were acidified with organic (oxalic, acetic, lactic, formic) and inorganic (sulphuric) acids and afterwards exposed to copper tolerant (Antrodia vaillantii, Leucogyrophana pinastri) and copper sensitive (Poria monticola, Gloeophyllum trabeum) brown rot fungal strains according to the mini block procedure. After eight weeks of exposure, the samples were isolated and their mass losses were determined. In addition, electron paramagnetic resonance (EPR) measurements on the exposed samples were performed. The EPR spectra of the samples decayed by A. vaillantii were very similar to those of the samples acidified with oxalic acid. Furthermore, acidification of the CCB impregnated samples made them significantly more susceptible to copper tolerant and copper sensitive brown rot fungi what can be clearly seen from weight losses.
M Humar, S A Amartey, M Šentjurc, F Pohleven

The Copper Tolerance of Mycelium vs. Spores for Two Brown Rot Fungi
2002 - IRG/WP 02-10422
The copper tolerance of two brown rot fungi, Gloeophyllum sepiarium and Oligoporus placentus, has been tested using both mycelia and basidiospores as inoculum sources. Mycelial growth of O. placentus on agar medium was shown to be much more tolerant to copper (as copper sulfate) than that of G. sepiarium. However, there was no difference in copper tolerance of basidiospores between the two species. Spores were much more sensitive to copper than mycelia in both species. This may explain why copper-based preservatives without co-biocide perform well in stake tests unless there is copper tolerant fungi mycelium in the soil.
S Choi, J N R Ruddick, P I Morris

Characterization of Poria indoor brown-rot fungi
1995 - IRG/WP 95-10094
The heterogeneous group of "Poria" fungi causing brown rot in buildings and also of wood in ground contact comprises Antrodia vaillantii, Antrodia serialis, Antrodia sinuosa, Antrodia xantha and Tyromyces placenta. These fungi have similar morphological appearance and biology. Their nomenclature has a confusing history and is still not uniform. As a consequence, misinterpretations may occur. SDS polyacrylamide gel electrophoresis showed a species-specific protein pattern for different cultures of Antrodia vaillantii separating the species from the other pore fungi as well as from Coniophora puteana and Serpula lacrymans. Electrophoresis also detected misidentifications. Investigations on growth rate, response to temperature, copper tolerance and wood decay revealed: Radial growth extension reached from 4 to 9 mm/d. Temperature optimum was 25 to 31°C. All withstood 1 hour at 60°C and some even 3 h at 65°C. Antrodia vaillantii was copper tolerant up to 0.05 M Cu. Wood weight loss after 20 weeks was higher by Tyromyces placenta (35%) and Antrodia sinuosa (33%) than by Antrodia xantha (21%), Antrodia serialis (16%) and Antrodia vaillantii (14%). Dual cultures revealed various inter- and intraspecific interactions and detected identity of differently coded cultures of a species. The former Poria vaporaria sensu Liese 'Normstamm II' for testing wood preservatives and the recent Poria placenta EN 113 strain FPRL 280 were shown to be either identical or at least sister monokaryons originating from the same individual.
O Schmidt

The effect of copper/chrome/arsenic (CCA) treated timber on soil fungi
1981 - IRG/WP 1131
The aim of this investigation was to study the effect of CCA treated wood on the microflora of soil with particular reference to copper tolerant soft rot fungi. The IRG collaborative field experiment was designed to monitor the performance of a range of preservative treated hardwoods with particular reference to soft rot in CCA treated timber (Dickinson 1976) and site 33 of this experiment was used in this investigation. The results clearly show that CCA impregnated timber affects the mycoflora of adjacent soil leading to increased frequency of isolation of copper tolerant fungi and particulary Phialophora spp.No significant increases in occurrence of copper tolerant fungi were noted in soil 1 cm from the wood surface indicating that the effect of treated timber is confined to a small area of soil.
R J Murphy, D J Dickinson

Influence of fungal exposure on the redistribution of copper in treated spruce wood
2002 - IRG/WP 02-10450
The redistribution of copper in treated wood after exposure to basidiomycete decay fungi is described. The micro-distribution of copper in copper(II) sulphate or copper(II) octanoate/ethanolamine treated Norway spruce wood before and after exposure to 3 different wood decay fungi was studied using transmission electron microscopy with X-ray microanalysis. The copper content of the mycelium and the nutrient medium was also determined by atomic absorption spectroscopy. Finally, light microscopic analyses of decayed samples was performed. Both copper-tolerant (Antrodia vaillantii) and copper-sensitive fungi (Trametes versicolor and Gloeophyllum trabeum) changed the distribution of copper in the treated wood after 16 weeks of exposure. The redistribution of copper in copper sulphate treated samples exposed to tolerant A. vaillantii was characterised by the excretion of oxalic acid and formation of copper oxalate in the cell lumens, on the surface of treated wood blocks and on the fungal hyphae. In the presence of ethanolamine, the formation of copper oxalate by A. vaillantii did not occur but instead diffusion of copper into regions of lower copper concentration (centre of the blocks and nutrient medium) took place. This type of redistribution/diffusion of copper was also observed when treated wood specimens were exposed to the copper-sensitive fungi.
M Humar, F Pohleven, R J Murphy, D J Dickinson, I Moris, M Zupancic, P Kalan, M Petric

Correlation between modulus of elasticity, mass losses and FTIR spectra of copper treated decayed wood
2006 - IRG/WP 06-10580
The composition of copper-based preservatives will change from copper-chromium to copper-ethanolamine, due to environmental demands. The most important drawback of copper-impregnated wood is the presence of tolerant fungal organisms that have developed an ability to degrade such preserved wood. In order to elucidate these processes, specimens (0.5×1.0×15 cm) made of Norway spruce (Picea abies) were vacuum-impregnated with copper-, chromium-, and copper-ethanolamine-based aqueous solutions (cCu=0.5%), and afterwards exposed to copper-sensitive Gloeophyllum trabeum and copper-tolerant Antrodia vaillantii for various times, between one and eight weeks. After incubation, specimens were isolated, and modulus of elasticity (MOE) losses determined using a nondestructive technique. Mass losses, FTIR spectra, and color changes were measured as well. The results showed that there is significant difference between brown rot decay caused by G. trabeum and A. vaillantii. Decay caused by A. vaillantii is more selective than that caused by G. trabeum. Additionally, it was proven that copper effectively protected spruce from G. trabeum, but not completely against A. vaillantii. Decay of copper-impregnated wood by copper-tolerant fungi is similar to decay of control, unimpregnated wood. Whereas decay of copper-impregnated specimens by G. trabeum, was effectively stopped in its initial stage.
M Humar, B Bucar, F Pohleven

Sensitivity to Copper of Basidiospores from Copper Tolerant Fungi: Fomitopsis palustris and Oligoporus placentus
2010 - IRG/WP 10-10707
Copper continues to be an important fungicide in wood preservation. It is the primary component of the preservatives that have replaced chromated copper arsenate for treated wood in residential construction in North America. However, a co-biocide is normally needed to protect against copper tolerant organisms. Previous work has shown that the spores of at least one copper tolerant fungus, Oligoporus placentus, were not very tolerant of copper. This explained the unexpectedly good performance of copper-only preservatives when just exposed to spores and not exposed to mycelium of such fungi. This work was designed to determine if the same was true of another copper-tolerant fungus that produces basidiospores in agar culture. An agar medium bio-assay was used to assess inhibition of basidiospore germination and mycelial growth of Fomitopsis palustris (Berk. et Curt) with O. placentus (Fr.) Gilb. & Ryvarden, as a known reference. The spores of F. palustris and O. placentus had the same copper sensitivity. The basidiospores were sensitive to copper concentrations between 20 and 50 times lower than their corresponding mycelium. These data confirm that spores of copper tolerant fungi are not very tolerant of copper.
C S Woo, P I Morris

Laboratory study of toxicity or tolerance of CCA preservative and heavy metal constituents copper, chromium and arsenic to Malaysian tropical fungi
2011 - IRG/WP 11-30579
CCA preservative and its constituent heavy metal tolerance and toxicity to 3 Malaysian isolates Phialophora fastigiata (soft rot fungus), Paecilomyces variotii (mould fungus) and an unidentified white rot Basidiomycete, was investigated by the modified ‘Strange-Smith’ agar-well-plate technique with 1.6% CCA concentration and the malt-agar-plate bioassay technique with a range of CCA and constituent metal salt concentrations of 0.0024 – 5%m/m. Daily linear hyphal extension was measured between 6 and 22 days depending on relative fungal growth rates. The slow growing Phialophora fastigiata sustained mean daily hyphal growth (mm) at relatively higher concentrations of CCA preservative (toxic limits: 0.24 – 0.48%m/m) and their heavy metal constituents (copper-salt: 5.0 – 10.0%m/m; chromium-salt: 0.076 – 0.24%m/m) than the faster growing mould isolate Paecilomyces variotii (CCA: 0.019 – 0.076%m/m; chromium-salt: 0.076 – 0.24%m/m) and the white rot Basidiomycete of intermediate growth rate (CCA: 0.076 – 0.24%m/m; copper-salt: 0.076 – 0.24%m/m; chromium-salt: 0.0095 – 0.019%m/m) except for arsenic-salt (Phialophora fastigiata: 0.076 – 0.24%m/m; Paecilomyces variotii: 0.48 – 0.95%m/m; Basidiomycete: 0.24 – 0.48%m/m). The results showing varying efficacies (toxicity versus tolerance) in vitro of CCA and their metal constituents between these fungi can have implications to ground-contact wood protection capabilities of CCA.
A H H Wong, T Mark Venås, N Morsing, C C L Tan, P K F Chong

Effectiveness of Copper Indicators in Treated Wood Exposed to Copper Tolerant Fungi
2014 - IRG/WP 14-20554
Wood treated with a copper based wood preservative will typically turn a green color. While the depth of copper penetration can be readily discerned from the green color of the copper it is standard practice in research and commercial treating plants to make use of a color reagent such as Chrome Azurol S, Rubeanic acid or PAN indicator to reveal the penetration more clearly. When copper treated wood is exposed to copper tolerant fungi discoloration of the original green color can occur. Reactivity of the treated wood with the color reagents can also be impaired. In this paper, the effectiveness of copper color indicators in detecting copper in wood attacked by copper tolerant brown rot fungi at early and late stages of decay was evaluated. Neither Chrome Azurol S nor PAN indicator could detect copper in the area where incipient and severe decay took place, even when chemical analysis showed significant levels of copper in these areas. Rubeanic acid was the only indicator which provided positive identification of copper in these samples. An FTIR study demonstrated that the loss of green color in copper treated wood by copper tolerant fungal attack is closely related to the formation of copper oxalate. The finding supports the theory that copper oxalate detoxifies copper and acts as a precursor for decay since a significant amount of copper oxalate was found in the area with discoloration but no visual decay, as well as in the area with severe decay. The results from this study suggest that the ineffectiveness of Chrome Azurol S and PAN indicators may be due to their inability to replace oxalate ion to form the colored complex with copper.
L Jin, K Brown, A Zahora, K Archer

Untreated and copper-treated wood soaked in sodium oxalate: Effects of decay by copper-tolerant and copper-sensitive fungi
2017 - IRG/WP 17-10888
Copper is widely used as the primary component in wood protectants because it demonstrates a broad range of biocidal properties. However, a key concern with using copper in wood preservative formulations is the possibility for brown-rot basidiomycetes to resist the toxic effect. Many brown-rot basidiomycetes have evolved mechanisms, like the production and accumulation of oxalate, which helps these fungi to tolerate copper-treated wood by detoxifying copper. The purpose of this study was to determine if untreated wood and copper-treated wood soaked in sodium oxalate influenced the rate of decay by brown-rot basidiomycete fungi. Both untreated and 1.2 % ammoniacal copper citrate-treated test blocks were subjected to an additional sodium oxalate treatment via two soaking methods (ten minute and two hour). Test blocks were exposed to two Fibroporia radiculosa isolates (FP-90848-T and L-9414-SP) and one isolate of Gloeophyllum trabeum isolate (MAD 617) and evaluated for weight loss at four and eight weeks. Decay was between 40-43% weight loss at week eight for F. radiculosa L-9414-SP when untreated blocks were soaked with sodium oxalate. F. radiculosa L-9414-SP demonstrated decay of 38% at week eight when copper citrate-treated blocks were soaked with sodium oxalate. F. radiculosa FP-90848-T decay was much lower for untreated blocks soaked with sodium oxalate (12-13%) and only slightly higher on copper-treated blocks soaked with sodium oxalate (19%) by week eight. G. trabeum MAD 617 decay was between 40-46% when untreated blocks were soaked with sodium oxalate. G. trabeum was unable to successfully decay the copper citrate-treated blocks soaked with sodium oxalate (0.5%) by week eight. The copper-tolerant and copper-intolerant test fungi used in this study demonstrated no major increase in decay when untreated and copper-treated wood was amended with oxalate.
K M Ohno, G T Kirker, A B Bishell, C A Clausen

Activity of Two Strobilurin Fungicides Against Three Species of Decay Fungi in Agar Plate Tests
2017 - IRG/WP 17-30704
The objective of this study was to examine the toxicity of strobilurin fungicides against wood decay fungi in order to assess their potential to act as a co-biocide for copper-based wood protection. Two strobilurin fungicides, Heritage (50% azoxystrobin active ingredient) and Insignia (20% pyraclostrobin active ingredients), and copper sulfate pentahydrate were tested against one white rot fungus (Trametes versicolor) and two brown rot fungi (Gloeophyllum trabeum and Fibroporia radiculosa). SHAM (salicylhydroxamic acid) was also included in the study because it is a known potentiator of strobilurin activity. All treatments were incorporated in an agar-based media and evaluated for their effects on mycelial growth rate. Based on minimum inhibitory concentration values found for F. radiculosa (a copper-tolerant fungus), Insignia was 5.5x more toxic than Heritage. SHAM at 100 ppm, increased toxicity 9x for Heritage and 1.2x for Insignia. In a 20-day toxicity screening study, the four one-compound treatments tested were: copper sulfate (5000 ppm), Heritage (20 ppm), Insignia (20 ppm) and SHAM (100 ppm). The two two-compound treatments were: Heritage + SHAM and Insignia + SHAM. The two three-compound treatments were: copper sulfate + Heritage + SHAM and copper sulfate + Insignia + SHAM. For the two copper-susceptible fungi (T. versicolor and G. trabeum), the treatments that caused complete growth inhibition were copper sulfate alone and the two three-compound treatments (copper sulfate + Heritage + SHAM and copper sulfate + Insignia + SHAM). For F. radiculosa, the two- and three-compound treatments were the most toxic, with maximum daily average growth rates statistically similar to the copper sulfate treatment. A key result, however, was that only the three-compound treatment of copper sulfate + Insignia + SHAM completely inhibited growth of the copper-tolerant fungus. Thus, it appears that pyraclostrobin, which is the active ingredient in Insignia, has greater potential than azoxystrobin to act as a co-biocide for completely inhibiting growth of a copper-tolerant fungus.
J D Tang, T Ciaramitaro, M Tomaso-Peterson, S V Diehl

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

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

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

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

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

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

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

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