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Current techniques for screening initial formulations against Basidiomycetes and soft rot
1978 - IRG/WP 2103
J D Thornton, H Greaves


The effect of treatment method on CCA efficacy in Corsican pine
1992 - IRG/WP 92-3723
As part of a study into the influence of application method on preservative efficacy Corsican pine (Pinus nigra) samples (50 x 50 x 400 mm³) were treated with a CCA formulation using Bethel, Steam/Bethel or Lowry processes. Full penetration of the preservative at a gross level was confirmed using a copper disclosing reagent. The preservative was allowed to fix and then samples were converted into mini-blocks (30 x 10 x 5 mm³) to produce decay test samples from various locations within the larger samples. After leaching, sets of replicate mini-blocks were exposed to the decay fungi Coniophora puteana FPRL 11E, Coriolus versicolor FPRL 28A, and Chaetomium globosum FPRL S70K. Equivalent sets of leached blocks, were analysed using atomic absorption spectrophotometry to determine preservative concentration and balance. The results of this study have been used to assess the effect of preservative application method on CCA efficacy. They also indicate how treatment method affects the distribution of the active elements of the preservative throughout the treated wood.
P R Newman, R J Murphy


Essais mycologiques sur poteaux traités à la Wolmanit C B
1974 - IRG/WP 339
D Ollier, C Jacquiot


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


Evaluation of the decay caused by Chaetomium globosum Kunze, in the course of time
1987 - IRG/WP 2288
The main research done on soft rot has been directed to determining, by microscopic study, the different stages of penetration into the wood of the fungi that cause it. On the basis of the information furnished by this research, in this work we have tried to quantify its effect, by evaluating the weight loss caused by Chaetomium globosum Kunce in wood of Pinus sylvestris L. and Fagus sylvatica L. in the course of time. The results obtained corroborate the existence of succesive stages of decay which is shown by large differences in the weight loss.
M T De Troya, A M Navarrete


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


Results from soft rot tests in vermiculite jars
1976 - IRG/WP 272
T Vihavainen


Some experiments with hexabutylditin against fungi
1977 - IRG/WP 388
The investigation was carried out in 1972 and 1973 to collect experimental data about the poisonousness of hexabutylditin (HBDT) against the woodrotting fungi Coniophora puteana (Coniophora cerebella), strain 15, and Chaetomium globosum, strain hexabutylditin was being manufactured by the Organisch Chemisch Instituut (O.C.I.) TNO, at Utrecht.
J W P T Van der Drift


Antagonism to spore germination in Scots pine
1990 - IRG/WP 1458
Germination of Lenzites trabea and Chaetomium globosum spores was observed directly on wood blocks, on water soluble extracts and on organic solvent soluble extracts from pine wood. In all cases pine heartwood was found to be antagonistic to spore germination but pine sapwood varied in its antagonism according to the method of drying. Chromatography revealed that extracts from antagonistic wood differed from those of non-antagonistic wood in their composition.
S M Gray


The use of image analysis to quantify soft rot decay
1992 - IRG/WP 92-2410
Image analysis techniques can provide quantitative information from visual images. As part of a wider interest in decay assessment methods we have investigated the application of image analysis techniques for quantifying soft rot decay by Chaetomium globosum in transverse sections of birch wood and bamboo. A method for reducing contamination of the section (and image) by the fungal hyphae and of staining prior to image analysis was developed. Decay cavities could be accurately detected and the extent of decay expressed in several different forms, with decay as a proportion of the wall area under analysis being the standard notation. Using a thin section exposure system it was found that, after a four day lag phase, soft rot decay in bamboo fibres increased at a constant rate, reaching 60% of wall area after fourteen days. The image analysis technique is rapid and straight forward to use, enabling the collection of both quantitative and qualitative data from the same area. It also allows different regions of a sample to be analysed separately. Further work with the technique is in progress to quantify decay in a wider range of timbers and to assess the effect of preservative treatments.
P J Wickens, R J Murphy


The effect of treatment temperature on the biological performance of CCA treated wood
1990 - IRG/WP 3624
Birch and Scots pine sapwood blocks were treated with several concentrations of CCA at three different temperatures: 5, 20 and 35°C. The treated wood was maintained at the appropriate temperature for the fixation period. Leached and unleached samples were then exposed in a soft rot monoculture test using Chaetomium globosum and a brown rot monoculture test using Coniophora puteana. The treatment temperature had little effect on the performance against brown rot but the performance of birch against the soft rot improved as the treatment temperature increased particularly after leaching.
S M Gray


Mapping soft rot decay distribution using image analysis
1993 - IRG/WP 93-20011
Image analysis has been shown to be a useful technique for the assessment of soft rot decay caused by Chaetomium globosum in birch and bamboo (Wickens and Murphy, 1992). The technique can permit assessment of decay in individual or small groups of cells and this has been used to undertake soft rot decay mapping in thin sections of bamboo. Assessments were made of the extent of soft rot decay with time in different fibre areas within individual vascular bundles. Comparisons were also made between bundles in different parts of the culm wall. The observations made indicated differences in the soft rot susceptibility of fibres depending upon their location in, and the age of, the culm wall. The location of fibres of different soft rot susceptibility could be mapped accurately using image analysis and this distribution compared with the known variation in fibre wall structure and composition. The advantages of image analysis techniques for such research are discussed.
P J Wickens, R J Murphy, G F M Watts


The use of plastic meshes in soft rot monoculture testing
1990 - IRG/WP 2353
Plastic meshes were introduced between the wood blocks and agar medium in a miniaturised soft rot monoculture test in order to minimise transfer of the preservative from the wood and mineral salts from the agar. Although several different sizes and types of mesh were used and the blocks were wetted up to an appropriate moisture content for soft rot attack the amount of decay was substantially reduced compared with the controls. Addition of mineral salts to the wood blocks in similar quantities to those in the agar aided decay but did not provide suitable conditions for maximum loss in weight.
S M Gray


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


Collaborative soft rot tests: Paper for discussion in Working Group II
1970 - IRG/WP II 5A
An account of the major part of the collaborative work on laboratory tests of toxicity of preservatives to soft rot fungi initiated by the European Homologation Committee at Delft in 1966 has been published in ‘Material und Organismen’ (1970) as a report of progress. The main objective of these collaborative tests, namely to establish a reliable and acceptable standard test method was not accomplished. The purpose of this paper is to comment upon the experience gained in order to facilitate discussions, at an IRG meeting, of any further proposals for achieving this objective.
J G Savory, A F Bravery


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


Accelerated decay tests to investigate postulated effects of tannins on CCA efficacy in wood
1988 - IRG/WP 3497
Five groups of blocks (10 x 10 x 5 mm³) viz., Pinus patula, Pinus patula impregnated to 4% (w/w) tannin; Eucalyptus grandis, Eucalyptus grandis with natural tannins extracted; and extracted Eucalyptus grandis with tannins returned as above; were prepared. Blocks from each group were then treated to 0, 5, 10 and 15 kg/m³ CCA and challenged in four 15-week decay tests, viz., soil burial, and exposure to monocultures of Chaetomium globosum, Coriolus versicolor and Coniophora puteana. The effect of tannin on CCA efficacy was evaluated by weight losses produced. The antimicrobial effect of tannin in wood not treated with CCA was demonstrated. However, the presence of tannin did not effect CCA efficacy in wood at the preservative retentions tested, since weight losses in CCA treated Pine and Eucalypt, both with and without tannins, were similar throughout all tests.
U L Scherer, A A W Baecker


Effect of microfibril orientation of bamboo cell wall on soft rot penetration hyphae
1994 - IRG/WP 94-10087
The effect of microfibrillar orientation of bamboo (Phyllostachys virideglaucescence) cell wall on the development of soft rot (Chaetomium globosum) penetration hyphae was investigated. It was found that the soft rot penetration hyphae normally followed the microfibril angle of the cell wall. Bamboo cell walls have alternating broad and narrow lamellae with different microfibrillar angles. The microfibrillar angle of the broad lamellae is mostly oriented vertically, whilst the narrow lamellae are mostly oriented horizontally. Soft rot penetration hyphae normally follow these microfibrillar angles.
O Sulaiman, R J Murphy


Soft-rot control in hardwoods treated with chromated copper arsenate preservatives. Part 3: Influence of wood substrate and copper loadings
1977 - IRG/WP 2100
The hypothesis is proposed that hardwoods need more chromated copper arsenate (CCA) than softwoods to protect them from soft-rot attack mainly because hardwoods are more readily consumed by soft-rot fungi. Simple model systems, using copper-supplemented agar or groundwood pulp treated with CCA showed that fungi tolerated more toxicant (copper) as more available substrate (malt) was provided. Soft-rot tests with CCA-treated hardwood blocks provided typical dosage-response curves when results were expressed as a ratio of substrate to toxicant (wood to copper). Furthermore, hardwoods needed 10 to 20 times more copper as CCA than softwoods to prevent soft-rot attack. When CCA was substituted by ammoniacal copper arsenate in 5 hardwoods, similar threshold values for soft-rot attack were obtained in terms of a wood-to-copper ratio. Hence, CCA may be behaving poorly against soft-rot fungi in our hardwood specimens mainly because the substrate contained too little copper. The practical implications of these results are discussed.
M A Hulme, J A Butcher


Preservative-efficacy of boric acid-triethanol amine solution against wood-decay fungi
1994 - IRG/WP 94-30050
Laboratory preservative-efficacy tests were conducted using boric acid-triethanol amine (BTEA) solution in accordance with the JIS A 9201 (1991) test method excluding the standard weathering process. Sapwood specimens of Picea jezoensis or Fagus crenata to achieve nominal retentions of 0.40-41.2 kg/m³ of boric acid were exposed to Tyromyces palustris, Coriolus versicolor, Serpula lacrymans or Chaetomium globosum, respectively. Mean percentage mass loss data showed the following threshold values: 1.65-2.13 kg/m³ for Tyromyces palustris; 1.60-1.94 kg/m³ for Coriolus versicolor; 0.43-0.83 kg/m³ for Serpula lacrymans; 8.0-23.8 kg/m³ for Chaetomium globosum. The values against Coriolus versicolor and Serpula lacrymans were lower than those of Tim-Bor® as boric acid retention.
S Doi, M Mori, Y Mineki


Application of a novel strength evaluation technique during screening of wood preservatives
1986 - IRG/WP 2262
The effectiveness of CCA and ACA in treated aspen mini stakes tested using a novel bag procedure, with unsterile soil fortified with Chaetomium globosum and Ceratocystis albida, is reported. Good agreement between toxic limits determined using the standard weight loss procedure, and those determined by the strength technique were found, with some indication that the strength loss method is more sensitive. The investigation also showed that the toxic limits for CCA (4.0-8.0 kg/m³) were twice those of ACA (2.0-4.0 kg/m³). In addition, based upon the strength loss, a CCA retention greater than 8.1 kg/m³ was required to prevent decay by Ceratocystis albida in this laboratory screening method.
J N R Ruddick


Influence of CCA and TnBTO on wood decay, under different oxygen levels and various initial moisture content
2001 - IRG/WP 01-10415
Fagus sylvatica (beech) and Pinus sylvestris (Scots pine) were impregnated by TnBTO (tributyl-tin oxide) and CCA (chromated copper arsenate). In wood blocks two levels of moisture content (50% and 100% of saturation point) were used. Three levels of oxygen concentrations (10, 21, and 50%) were chosen. Treated and untreated wood were exposed to three fungi (C. versicolor a white rot, C. puteana, a brown rot, and C. globosum a soft rot). The results showed when TnBTO was used and wood samples exposed to C. versicolor between treated (TnBTO) and untreated specimens was no a big difference in weight losses. Using high moisture content (100%) in wood blocks caused very low weight losses in all treatments to be appeared. When CCA was applied decay by C. puteana was very decreased in Scots pine, therefore, there was a large difference in weight losses between treated and untreated wood. Low oxygen and high moisture content in treated samples caused wood decay by C. puteana did not occur. In the case of C. globosum effect, increasing the moisture content caused that wood decay in all specimens (treated and untreated) to be increased. However, low oxygen concentration in middle moisture content (50% SP) increased decay in beech.
S M Kazemi, R J Murphy, D J Dickinson


Diffuse cavity formation in soft rot of pine
1992 - IRG/WP 92-1541
A new type of soft rot of southern pine longitudinal tracheids is described. In this type, soft rot cavities form by diffuse degradation of the S2 cell wall layer by hyphae growing within the cell wall. Erosion is diffuse and irregular as opposed to the restricted, periodic erosion typical of type 1 soft rot cavity formation. Proboscis hyphae remain small (diameter 0.6 to 0.8 µm) and rapidly autolyze. These proboscis hyphae are not easily recognizable with light microscopy, especially at later decay stages, and require transmission electron microscopy to confirm their presence. This may be an alternative interpretation of the type 2 soft rot of softwoods described previously as being caused by lumenal hyphae through an intact S3.
S E Anagnost, J J Worrall, C J K Wang


Addendum to paper for discussion in Working II
1970 - IRG/WP II 5B
In view of the limited time that will be available for discussions in Nancy, this addendum has been prepared. Arising from the previous collaborative work and Mr Bravery’s visit to most of the co-operating Institutes, a scheme of work entailing tests carried out 1) by a technique chosen by individual Institutes; 2) by an agreed standardised technique would appear to be the best approach. A complete programme of work would embrace a) agar tests; b) soil tests -in sterile soil -in unsterile soil. Clearly allocation of priorities eg to concentrate in the first place on tests in unsterile soil, will be needed. To facilitate discussion on a standardised technique, possible methods for conduct of both agar and soil tests are included in appendix I and II respectively. Full details of practical procedures and methods of computing results have not been included.
J G Savory, A F Bravery


Susceptibility of CCA treated North American hardwoods to Chaetomium globosum decay
1998 - IRG/WP 98-10278
Seven species of hardwood, Beech (Fagus grandifolia), Basswood (Tilia americana), Maple (Acer rubrum), Oak (Quercus rubra), Trembling Aspen (Populus tremuloides), White birch (Betula papyrifera) and Yellow poplar (Liriodendron tulipifera) were vacuum or pressure impregnated with CCA, at four retention levels. The CCA was allowed to fix in the wood at 35°C. Red pine (Pinus resinosa) was also included in the experiment as a control. Each of the wood species was exposed to the soft rot fungus, Chaetomium globosum. There is a marked difference in the CCA fixation time between the wood species. Oak fixed the first followed by beech and maple. Red pine and white birch took intermediate times to fix and the last set of species to fix were the yellow poplar, aspen and basswood. The leaching results of the same revealed that faster fixation resulted in increased leaching losses, especially of arsenic. Relative leaching was higher at lower retention. There was not a direct correlation between mass loss and CCA fixation and leaching properties suggesting that factors other than CCA persistence and initial distribution control soft rot susceptibility of these species.
U Srinivasan, Y T Ung, P A Cooper


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