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Preliminary note on the fungal problem of rubber wood
1983 - IRG/WP 3246
Susceptibility of rubber wood to fungal attack limits its wider utilisation. Fungal problems encountered in treating rubber wood with boron compounds by diffusion process have been discussed. Sodium pentachlorophenoxide and 2-thiocyanomethylthio benzothioazole (TCMTB) were investigated for possible control of fungal growth during diffusion storage and their performance has been reported.
R Gnanaharan

Preventing fungal attack of freshly sawn lumber using cinnamon extracts
2007 - IRG/WP 07-30432
The potential for using cinnamon oil as an anti-mold and stain compound was investigated on ponderosa pine sapwood. Cinnamon oil was highly effective when used in ethanol, but its activity declined when it was mixed with only water. Attempts to enhance water solubility with surfactants improved solution stability, but had no apparent effect on biological activity. Further studies with other co-solvents are planned
Shujun Li, C Freitag, J J Morrell

Fungal Stain Development in Canadian Hardwood Logs
2004 - IRG/WP 04-10505
In most sawmills around the world, trees are harvested into logs and stored in the forest or in a log yard for a period of time before being sawn into lumber. These logs may be attacked by various pigmented fungi, which results in staining of the wood. Since hardwood species are used to a great extent in furniture manufacturing and in the making of other valuable wood products, the reduction of wood staining in these species has a significant economic impact. This study investigated storage time limits in sawmill yards for the major Canadian hardwood species, with and without water sprinkling. Sugar maple, yellow birch, and white birch trees were selected and felled in summer and winter and transported to two sawmills in Quebec, Canada. At each site, one group of logs was dry-stacked and another was stored under water sprinkling in the sawmill yard. Until October, inspections of dry-stacked logs were conducted every 2 weeks and the water-sprinkled logs were inspected every 4 weeks. The logs were cut into discs and wood moisture content was measured; fungal stain and check development were also examined. The results showed that 3 weeks after harvesting, fungal stain had not occured on summer-harvested sugar maple or yellow birch logs. Minor staining was measured in logs of both species after 5 weeks in storage. Significant staining was found after 7 weeks of storage and serious staining occurred after 9 weeks or more of storage. After 13 weeks in storage, most sapwood of the dry-stacked logs was stained. Log ends had more staining than internal sections. On exposed wood without bark protection, most fungal infections started within 5 weeks of felling. However, after 5 weeks of storage, when wood moisture content had decreased to a certain level, thus providing less protection, staining fungi began to attack bark-covered wood. The results of the second trial showed that winter-harvested logs were more resistant to fungal stain than summer-harvested logs. Moreover, those harvested in the winter did not sustain much staining the following spring. Until the end of June of the following year, only 1.9% wood of dry-stacked sugar maple logs, 2.2% wood of yellow birch logs, and 2% wood of white birch logs were stained. Stain development in the logs increased rapidly in July and August. White birch was most affected by stain, followed by yellow birch, and, finally, sugar maple. Water-sprinkled logs were well protected from stain. Check development on logs under the two storage methods showed that, in dry storage, sugar maple logs developed more physical checks than the yellow birch and white birch. Most checks formed on the ends rather than in internal sections of the logs. Water sprinkling limited check formation on all logs. Fewer checks developed in winter-harvested logs (site two) than in summer-harvested logs (site one).
Dian-Qing Yang, M-C Bisson

Using image analysis to rate wood stain trials
1993 - IRG/WP 93-10034
Assessing the extent of fungal discoloration on wood during laboratory trials is a subjective process which provides an opportunity for considerable variation between individual evaluators of specimens. The development of reliable systems for automatically assessing discoloration would minimize evaluator bias and permit comparisons between results from different laboratories. The use of image analysis for this purpose was explored on specimens treated with selected concentrations of an anti-stain chemical and inoculated with an array of stain fungi. The results indicated that ratings by the image analysis system were comparable to those produced-by a human evaluator. Further studies are contemplated to refine this system and improve the correlations with human ratings.
C M Sexton, A G Maristany,C C Brunner, J J Morrell

Sapstain development on Jack pine logs in Eastern Canada
2000 - IRG/WP 00-10358
During 1998-99, a study was initiated to investigate the influence of seasons, log types and storage time on the sapstain development on jack pine logs at two sites in Eastern Canada. Jack pine trees (Pinus banksiana) were harvested into whole-tree and cut-to-length logs in spring and in autumn. Sapstain development was examined in these logs at 2 to 4 week intervals after felling. The mean stain coverage and maximal radial penetration of stain in wood were measured from the discs of the sampled logs. The spring trial showed that sapstain did not develop significantly on jack pine logs within four weeks after trees were cut; however, the severity of stain increased proportionally with the storage time. For both test sites, the full-tree stems were stained more than the cut-to-length logs. All logs were seriously stained after the three months summer storage. The main fungus isolated from stained wood was Ceratocystis coerulescens. Bark beetle attack was found in logs within four weeks after the trees were cut. The bark beetle was Ips pini. After three months in the summer storage, decay started to develop among these logs and the main causal species was Schizophyllum commune.
Dian-Qing Yang, R Beauregard

Evaluation of white-rot fungal growth on Southern Yellow pine wood chips pretreated with blue-stain fungi
2000 - IRG/WP 00-10349
White-rotting basidiomycetes do not colonize on southern yellow pine. This study seeks to reduce the resinous extractive content of southern yellow pine by treating it with blue stain fungi. The mycelial growth of wood-inhabiting ligninolytic white-rot fungi can be achieved on pretreated southern yellow pine wood. Aureobasidium, Ceratocystis, and Ophiostoma spp. removed 70% to 100% of the extractives from the southern yellow pine wood within a period of 3 to 6 days. Griofora fondosa, Hericium erinaceus, and Pleurotus ostreatus colonized readily after the treatment. As a result, ligninolytic white-rot fungi can be easily colonized on southern yellow pines pretreated with blue stain fungi.
S C Croan

The role of chitinase in bioprotectant activity against staining fungi
1996 - IRG/WP 96-10175
Chitin is an important structural component of the hyphae of many wood staining fungi and its disruption can lead to dramatic declines in their growth. A number of bioprotectants have been shown to produce chitinases in liquid cultures, but the role of these enzymes in bioprotection remains poorly understood. The levels of these enzymes was studied by inoculating ponderosa pine sapwood wafers with liquid cultures of either Serratia plymuthica or Trichoderma harzianum. The wafers were then inoculated with a mixture of wood staining fungi and incubated for 4 weeks at 23 to 25°C. The wafers were then evaluated for degree of stain prior to extraction and analyzed for chitinase activity. Chitinase activity appeared to increase with increasing degree of bioprotection for several isolates of Trichoderma harzianum, while the relationship was less clear with Serratia plymuthica.
J Liu, J J Morrell

Effects of microclimate, wood temperature and surface colour on fungal disfigurement on wooden claddings
2012 - IRG/WP 12-20490
Wooden claddings are common in façades in Norway, and Norway spruce (Picea abies) is the most frequently used species. The cladding is a major part of the facade, and it has visual requirements that may define the aesthetic service life. The visual changes that occur during weathering can be colour changes, abrasion or wear, blistering, flaking, and even cracks in the wood or coating, but more often growth of mould and blue stain fungi are the main challenge. A field test with synchronous monitoring of relative humidity, air temperature, material temperature and wood moisture content in Norway spruce claddings has been established in southern Norway as part of the ClimateLife project. Visual evaluation of blue stain and mould growth according to EN 927-3 was performed, and evaluation data after 10 months exposure is presented. The objectives were to study the effect of 1) environment, 2) cardinal direction and 3) colour of the cladding on growth of blue stain and mould fungi, and further study the variation in relative humidity, air temperature in front of a surface and the material temperature due to change in 1) environment, 2) cardinal direction and 3) colour of the cladding. After 10 months exposure, the red coating system had lowest mould ratings and the uncoated claddings had the highest. Claddings facing south tend to have higher mould ratings than those facing north. No difference was found between shaded and open environment. The relative humidity was higher in front of the claddings exposed in a shaded environment compared to an open environment, and in an open environment the relative humidity was lower against south than north. The temperature in front of the red coloured claddings was highest. Except for the red-coated claddings, the air temperature was higher than the material temperature.
L Ross Gobakken, G I Vestøl

Fungal growth on coated wood exposed outdoors: influence of coating pigmentation, cardinal direction and inclination of wood surfaces
2017 - IRG/WP 17-10896
The objective of the SERVOWOOD project was to develop and establish European Standards that will facilitate the prediction of service life for exterior wood coatings. One of the objective of this project was to study fungal growth of the field exposed panels. Two coatings applied in 2 and 3 coats were exposed for one year outdoors at 45° south: one solventborne (alkyd based) and one waterborne (acrylic based) both in clear and pigmented versions. Fungal growth visually assessed was compared to fungal enumeration and the influence of exposure time on the main fungal species was studied. Results clearly showed that a lower fungal growth was observed on pigmented coatings. Despite the clear solventborne coating included a higher amount of biocide it was more susceptible to blue stain than the pigmented recipe. A new multifaceted exposure rig (MFER) designed for the project also contributed to the study of fungal growth. It allowed samples to be exposed with 9 different exposure directions and angles. The exposure using this MFER has shown that the worst cases (high area and high intensity of blue stain) were for samples with the clear coating exposed to north 45° and at the top of the MFER (horizontal surfaces). For any cardinal direction all surfaces inclined at 45° displayed more blue stain than vertical surfaces due to higher moisture content.
L Podgorski, C Reynaud, M Montibus

Plasma-assisted bleaching of blue-stain from lodgepole pine wood
2017 - IRG/WP 17-40799
We hypothesize that plasma will etch wood and fungal hyphae in blue-stained lodgepole pine, and increase the ability of hypochlorite bleach to remove discolouration from blue-stained wood. Blue-stained lodgepole pine wood was exposed to a glow-discharge plasma derived from water, and the surface wettability, permeability and colour of the treated wood was measured. Plasma-treated wood was dipped in sodium hypochlorite bleach and the colour of the blue-stained wood was re-measured. Scanning electron and light microscopy was used to observe changes in the microstructure of plasma-treated blue-stained wood. We collected hyphae from the blue-stain fungus Grosmannia clavigera and used scanning and transmission electron microscopy to examine the effects of plasma on the structure of fungal hyphae. Plasma treatment increased the wettability and permeability of blue-stained lodgepole pine sapwood and removed some of the blue-discolouration from the wood. Plasma modified the microstructure of lodgepole pine wood by etching bordered pits and cell walls at wood surfaces. Bleaching of blue-stained wood by sodium hypochlorite bleach was significantly improved by plasma pre-treatments. The effectiveness of the plasma pre-treatment at removing blue-stain was influenced by the duration of the treatment. Plasma etched hyphal walls of the blue-stain fungus and degraded melanin. Our results demonstrate that plasma treatments are able to remove the discolouration from blue-stained wood, and increase the effectiveness of a bleaching agent because they degrade and remove blue/black fungal hyphae, open-up bordered pits and enable more of the bleach to be absorbed by wood. The development of plasma etching devices capable of operating at high speed and atmospheric pressure are needed to develop plasma-assisted bleaching processes that can be used commercially to remove fungal staining from wood.
A Jamali, P D Evans

Questionnaire - Fungal decay types
1985 - IRG/WP 1265
T Nilsson

Screening potential preservatives against stain and mould fungi on pine timber in Zimbabwe
1995 - IRG/WP 95-30063
The search for environmentally and toxicologically safer chemicals for use in the timber preservative industry against stain and mould fungi has been intensified during the past few years. Results of field tests with two chemicals previously evaluated in the laboratory are presented. The conventional sodium pentachlorophenate was the more efficacious chemical against stain and mould fungi, providing up 90% control at a concentration of 2.5%. A potential alternative, Stopstain a borate-based chemical, gave results only slightly better than the untreated control timber, at a concentration of 5%. Unless the environmental cost and toxicological hazards of traditional chemicals are highlighted the newer and safer chemicals will be reluctantly accepted by industry as they are regarded as being prohibitively expensive.
A J Masuka

Improvements of monitoring the effects of soil organisms on wood in fungal cellar tests
1996 - IRG/WP 96-20093
Accelerated testing the durability of preservative treated timber in a so called "fungal cellar" or "soil-bed" to evaluate its performance in ground contact is widespread practice. In order to obtain a more accurate and reproducible estimate of preservative performance, several institutes, among them the BAM in Berlin, have routinely carried out static bending tests in addition to visual examination. These tests were usually performed with a defined maximum load or deflection path regardless of the remaining degree of elasticity of the test specimens. Recent studies at the BAM revealed that by modifying the method, i.e. by restricting the applied load to the non-destructive interval for each individual test specimen, the calculated modulus of elasticity (MOE) reflect the changing strength properties caused by biological deterioration and allow within a relatively short time valuable predictions on the service life of the treated timber in soil contact.
I Stephan, S Göller, D Rudolph

The restricted distribution of Serpula lacrymans in Australian buildings
1989 - IRG/WP 1382
Temperature data has been gathered over a number of years, not only for flooring regions of various buildings in Melbourne, but also within roof spaces and external to the buildings. Findings are discussed in relation to the distribution of Serpula lacrymans within Australia, its restriction to certain types of building construction and its restriction to flooring regions. The subfloor spaces of badly-ventilated, masonry buildings are highlighted as being better suited than are the subfloor spaces of, for example, Japanese buildings for the activity of this fungus. Hence Serpula lacrymans is very restricted in its distribution in Australia, yet where it is active it does grow rapidly and causes rapid flooring failures.
J D Thornton

Blue stain in service on wood surface coatings. Part 3: The nutritional capability of Aureobasidium pullulans compared to other fungi commonly isolated from wood surface coatings
1993 - IRG/WP 93-10035
The nutritional capability of Aureobasidium pullulans was previously examined, using agar plate tests, with regard to nutrient sources that are potentially available in fresh and weathered wood (Sharpe and Dickinson, 1992). This study compared these findings with the nutritional capability of four other fungi (Alternaria sp., Cladosporium cladosporoides, Stemphylium sp. and Trichoderma sp.) commonly isolated from wood surfaee coatings. The liquid culture techniques were used to assess the relative abilities of the fungi to utilise a range of simple sugars, wood sugar alcohols, hemicelluloses, cellulose and lignin degradation compounds. The observations were used to explain why Aureobasidium pullulans is able to occupy so successfully, often in monoculture, the wood-paint interface niche.
P R Sharpe, D J Dickinson

Report on the activities of the European Standardization Committee CEN/TC 38 'Methods of Testing wood preservatives'
1980 - IRG/WP 279 E
G Castan

The accelerated field simulator (= fungal cellar)
1982 - IRG/WP 2170
G C Johnson, J D Thornton, H Greaves

Mould resistance of lignocellulosic material treated with some protective chemicals
1984 - IRG/WP 3294
Effectiveness of preserving lignocellulosic material against moulding by treatement with water solutions of commercial wood preservatives and mixtures of various inorganic salts was investigated and compared with the effectivenes of sodium pentachlorophenoxide and boric acid.
K Lutomski

Field trials of anti-sapstain products. Part 1
1991 - IRG/WP 3675
The results obtained in two field tests of anti-sapatain products, carried out in four locations in Portugal, are presented. Boards from freshly cut logs were hand-dipped, close staked and left to dry for periods from four to six months. The results obtained seem to indicate that some of the products tested performed at least as well and sometimes better, than a 3% NaPCP solution which was used as control product.
L Nunes, F Peixoto, M M Pedroso, J A Santos

Evaluation of the effectiveness of three microbiocides in the control of sapstains
1982 - IRG/WP 3212
Results of field test on the effectiveness of BUSAN 30, CAPTAN, FOLPET against mould and sapstain in Pinus elliottii are presented. The viability of use of FOLPET in Brazil as an alternative to sodium pentachlorophenate is also discussed.
S Milano, J A A Vianna Neto

Low temperature drying conditions of Pinus radiata wood for avoiding internal stain
1989 - IRG/WP 3507
It has been observed that, if in little sawmills, timber is dried with a low temperature schedule, it arrives at destination with internal sapstain besides of superficial mould. In this study, the lowest drying temperature at which wood should be exposed for sterilization, which results to be 52°C, is searched. It is not possible to avoid entrainment of pentachlorophenol, even though a waiting period of 72 hours after dipping the wood in a pentachlorophenate/borax solution before drying is considered. The residual content of pentachlorophenol in wood should be at least 400 µg/cm² or the moisture content less than 23% for avoiding the development of mould.
M C Rose

Evaluation of new creosote formulations after extended exposures in fungal cellar tests and field plot tests
2000 - IRG/WP 00-30228
Although creosote, or coal tar creosote, has been the choice of preservative treatment for the railroad industry since the 1920s, exuding or "bleeding" on the surface of creosote-treated products has been one incentive for further enhancements in creosote production and utility (Crawford et al., 2000). To minimize this exuding problem, laboratories such as Koppers Industries Inc., USA, and Commonwealth Scientific and Industrial Research Organization (CSIRO), Division of Chemical and Wood Technology, Melbourne, Australia, have developed changes in processing of coal tar that produce distillates with fewer contaminants. This "clean distillate" is then used to formulate "clean creosote" as a preservative. These new, unique creosote formulations are being investigated as part of a program to enhance the use of regionally important wood species in the United States. Four retention levels of each of two new creosote formulations creosote, one pigment-emulsified creosote (PEC) and one creosote formulation that meets the AWPA Standard C2-95 for P1/P13 creosote (AWPA, 1995a), were applied to two softwood species and two hardwood species. Two laboratory procedures, the soil-block and fungal cellar tests (accelerated field simulator), were used to evaluate the four creosote formulations. These procedures characterized the effectiveness of the wood preservatives. The soil-block tests were used to determine the minimum threshold level of the preservative necessary to inhibit decay by pure cultures of decay fungi. In general, the soil block tests showed there was little difference in the ability of the four creosote formulations to prevent decay at the three highest retention levels as summarized in a previous report by Crawford and DeGroot (1996). The soil-block tests will not be discussed in this report. Fungal cellar tests expose treated wood to mixtures of soil-borne fungi that promote accelerated attack. Crawford and DeGroot (1996) discussed the evaluation of the creosote formulations after 17 months of exposure in the USDA Forest Service, Forest Products Laboratory (FPL), fungal cellar. At that point in time data from the fungal cellar tests showed that softwoods are protected better than hardwoods for all four formulations of creosote tested. This report will discuss exposure of the fungal cellar stakes upto 36 months. In addition, field stake tests are being used to verify service life of the new creosote formulations in vivo. Results from accelerated tests are indicative of field performance, but the correlation between laboratory and field results is still being investigated. Field stake tests are regarded as critical, long-term evaluations that provide results most directly related to the performance of treated products in service. In this study, we report on the performance of the creosote formulations after five years of exposure in field tests.
D M Crawford, P K Lebow, R C De Groot

Fungal and bacterial attack of CCA-treated Pinus radiata timbers from a water-cooling tower
1991 - IRG/WP 1488
Transmission electron microscopy of decaying CCA-treated Pinus radiata timbers from an industrial water cooling tower showed presence of a thick biofilm covering some areas of the wood. The biofilm contained various morphologically distinct forms of microorganisms embedded in a slime. The study provided evidence of the activity of soft rot fungi and tunnelling and erosion bacteria in wood cells. The extent of damage to wood cells due to microbial activity varied, combined fungal and bacterial attack having the most damaging impact.
A P Singh, M E Hedley, D R Page, C S Han, K Atisongkroh

Rapport sur l'activité du CNE/TC 38 'Méthodes d'essais des produits de préservation du bois'
1980 - IRG/WP 279
G Castan

Blue stain in timber in service. Results of co-operative tests to compare different artificial weathering systems 1981-82
1983 - IRG/WP 2193
The paper describes results of the third phase of co-operative laboratory experiments comparing the effects of different artificial weathering systems on chemicals to control blue-stain in service. Atlas, Xenotest and Marr equipments are shown to give essentially the same results for 5 of the 6 chemicals tested.
A F Bravery, D J Dickinson

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