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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
Comparison of the in-ground performance of pigment emulsified creosote (PEC) and high temperature creosote (HTC)
2000 - IRG/WP 00-30217
A long-term field trial was conducted in Australia to compare the in-ground performance of two oil-borne preservative formulations, conventional high temperature creosote (HTC) and a modified creosote formulation, pigment emulsified creosote (PEC). Three retentions (50, 100 and 200 kg/m³) were targeted for each formulation. An additional retention of PEC formulation (308 kg/m³), which contained 200 kg/m³ of creosote, was also included in the trial. Treated and untreated Eucalyptus regnans sapwood specimens were exposed horizontally below-ground to a range of economically important species of subterranean termites and wood decay fungi at two tropical and one semi-arid test sites. After 11 years of exposure, specimens treated with 200 kg/m3 of HTC and specimens treated with PEC containing 200 kg/m3 of creosote continue to perform well. Results of the field trial demonstrate that PEC will perform comparably to HTC on an equivalent creosote retention basis.
J W Creffield, H Greaves, N Chew, N K Nguyen
The influence of moisture content and wood pH variation on fungal melanin formation in wood substrates
2011 - IRG/WP 11-10759
Wood decay patterns are strongly influenced by the conditions of the wood substrate, including moisture content and pH. In an antagonistic environment some fungi respond with pigment formation that helps to isolate and protect their mycelium. This is often associated with slower fungal growth and delay of wood mass loss. Dark colored melanin is the most common pigment formed by wood decay fungi, and it is produced in consecutive granule depositions in the lumens of the wood cells to form distinctive zone lines. To investigate the melanin formation, sugar maple and beech samples were inoculated with different strains of Trametes versicolor and Xylaria polymorpha. To test the influence of pH on melanin formation, wood samples were adjusted with buffer solutions to different pH values; to test the influence of moisture content in pigment formation, wood samples were incubated at different vermiculite substrate moisture contents. Maximum pigment production occurred at pH 4.5 for beech and pH 5 for sugar maple inoculated with Trametes versicolor, while Xylaria polymorpha produced external pigmentation in beech treated with buffer at pH 5. Wood samples with the lowest moisture content had higher black pigment accumulation.
D Tudor, S C Robinson, P A Cooper
Potential Use of the Pigment from Scytalidium cuboideum and Chlorociboria aeruginosa as an UV-light Protection Additive in Oil Finishes
2019 - IRG/WP 19-40868
UV-light degradation of wood is one of the top reasons for consumer replacement of outdoor wooden structures. This type of degradation is seldom mechanical, and is instead often motivated by loss of aesthetics (graying). There are numerous commercial products available on the market that deal with this loss of color, many of which contain added pigments to ‘rejuvenate’ or ‘revitalize’ greyed wood. These pigments are almost uniformly synthetic. In contrast, pigments from wood decay fungi (spalting), which have been used in woodworking since the 1400s (intarsia), have remarkable optical (UV-light resistance) properties due to their naphthoquinonic configuration. These fungi have evolved to digest certain wood components and to persist in their environment, making them very stable. In recent years the pigments made from these fungi have been extracted and tested across numerous substrates, from solar cells to textile dyes. In this work, researchers extracted pigments from Scytalidium cuboideum (red pigmentation) and Chlorociboria aeruginosa (blue-green pigmentation), solubilized the pigments in raw linseed oil, and tested the resulting solution on samples of Douglas-fir (Pseudotsuga menziesii) and western white pine (Pinus monticola). These mixtures were compared against a ‘stain and coat’ treatment (utilizing an aniline stain and coated with raw linseed oil), raw linseed oil, and untreated wood. The wood samples were then placed in an accelerated weathering machine (Q-UV), using the ASTM G154 standard, for 500 and 1000 hours. The results showed that while no visible color change occurred to the wood when the pigmented oil was applied, the red pigment oil significantly lowered the coating degradation for both wood types at an exposure of 500 hours. The results show the potential applications for fungal pigments in the wood coating industry, as it offers an increased coating service life. As there is a shift to renewable products, the pigments from wood decay fungi show potential as additives for wood coatings.
S M Vega Gutierrez, D W Stone, R He3, P T Vega Gutierrez, Z M Walsh, S C Robinson
Pigment production by the spalting fungus Scytalidium ganodermophthorum and its industry potential
2020 - IRG/WP 20-10957
Scytalidium ganodermophthorum is best known as a pathogen of cultivated mushrooms, with infected cultures turning yellow in color. The fungus is also used in the art form known as ‘spalting’ to produce yellow, green, and purple colors in wood for decorative purposes. Wood colored by fungus in this manner has been traditionally used in the creation of fine art and woodworking since the 16th century in Europe. However, most fungal species known to spalt wood only produce a single color of pigment, making S. ganodermophthorum unique. Other pigments isolated from fungi in the family Helotiales have shown unique physical characteristics including UV-stability, bioactivity, and semiconduction. This has stimulated research into their use across a range of fields including organic photovoltaics and environmentally friendly dyes. In order to identify the pigments produced by S. ganodermophthorum and allow for research into their physical properties, the growth conditions needed to stimulate production of different pigments by the fungus must be identified. This study characterizes the differential coloration of S. ganodermophthorum cultures, including variation over time and across a range of pHs. Pigment production was found to change with colony age, with initial yellow extractions transitioning through a series of green colors to a purple/red color with time. In addition, growth across multiple pHs was tested for potential changes in pigmentation, and pigment response to pH change was tested to identify if changes in color were due to only one or multiple pigments. Growth was found to vary across pH range, and the presence of multiple pigments was indicated. With the innovative potential of pigments from other spalting fungi established, identification of new fungal pigments from S. ganodermophthorum could lead to development of new forest-based green technologies including textile coloration, optoelectronics, and wood protection
R C Van Court, P Vega Gutierrez, S C Robinson
Extraction of fungal colorants for their use in coloured coatings for wood
2022 - IRG/WP 22-40938
Microorganisms are highly interesting for the production of useful metabolites. Such metabolites are e.g. colorants, that can easily be produced on industrial scale and low material costs. To date some microbial produced colorants are used in textile- and food industry because of their low toxicity and sustainability compared to synthetically produced colorants. However, little is known about the use of such colorants in wood protecting coatings. Therefore, the present work focused on the isolation of colorant producing fungi, cultivation of these fungi and extraction of their colorants to produce coloured coatings for wood protection. About 10 interesting organisms have been isolated from soil, air and water samples, mainly producing the colours yellow/brown and red/pink. They have been grown for colorant production and extraction of colorants took place by simple extraction with a suitable solvent or Soxhlet extraction. With the colorant of the fungus HFA 136 Scytalidium cuboideum crystals from around 1,5 cm of length with high purity could be produced. Purity was checked by NMR- and mass spectrometry. Received crystals were incorporated in a base coating for wood protection and applicated on wooden samples for testing the stability against photooxidation of the colorant in the coating. Experiments for light-stability are still ongoing but first experiments show promising results. However, the present work shows, that colorant producing fungi are common and can be isolated easily from environmental samples. There is a lot of research to be done on this topic, that is seminal for future trends regarding the increasing environmental and health awareness.
K Kusstatscher, N Pfabigan, M Senoner, L Orlowsky, A Steitz, B Forsthuber, S Niedermayer, R Gründlinger
Questionnaire - Fungal decay types
1985 - IRG/WP 1265
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
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
The accelerated field simulator (= fungal cellar)
1982 - IRG/WP 2170
G C Johnson, J D Thornton, H Greaves
An attempt to evaluate wood resistance against fungal decay in non-sterile conditions by measuring the variation of resistance to bending test
1988 - IRG/WP 2308
The main object of this work was to determine the variation of strength on large test specimens of wood (800 x 45 x 45 mm³) when exposed to accelerated fungal attacks close to natural conditions, out of test vessels. The modulus of elasticity (MOE) and the modulus of rupture (MOR) have been assessed. Thereby, the natural resistance of the wood species to fungal decay, the efficiency of preservative as well as the treatment applied are discussed. The wood tested is a guianese secondary species (Couma guianensis). The fungi tested are two guianese strains of brown and white rot. The exposure time is 12 weeks. No mould contamination has been recorded by use of a selective fungicide. The results obtained show that it is possible to infest in nonsterile conditions large wood specimens. Furthermore, modulus of rupture appears to be the most reliable criterion. The investigation, that requires limited equipment and staff could be performed in any tropical research station as it has been done at CTFT, French Guiana center.
L N Trong
A short note on fungal decay in K33-treated poles
1982 - IRG/WP 1169
Soft rot cavities and erosion of the lumen have been found in K33-treated Pinus sylvestris poles from the years 1956-66 by microscopic studies. Poor treatment quality has been proved for some of these poles. The microscopy showed an unusual pattern of attack, and pre-treatment decay is suspected but not yet proved. Sounding the poles and using the Pilodyn indicated decay, but poking did not. Quantification of the attacks was possible only by microscopic studies.
Biological and chemical observation on the early fungal colonization of TBTO treated Swedish redwood stakes
1984 - IRG/WP 3311
Data on the early fungal colonization of Swedish redwood stakes, impregnated with 1% TBT0 / 0.5% dieldrin solution, both by double vacuum impregnation and immersion processes are presented. Results of chemical analyses of wood samples from the outer 1 mm of separate painted and unpainted stakes, exposed over the same twelve month period, are also discussed.
R Hill, A H Chapman, A Samuel, K Manners, G Morton
A direct method for testing plywood and particle boards against fungal decay
1984 - IRG/WP 2214
A method directly inspired from the French standard testing method of the resistance of particle boards against fungal decay (AFNOR N° 51.295 May 1980) is described. But in that experimentation, the infestation is localized and realized in non sterile conditions. Small blocks of Fagus sylvatica (60 x 20 x 10 mm³) used as " inoculates " are infested with basidiomycetes, in Kolle flask for 4 to 6 weeks, then tightly pressed against the middle part of the test specimens (190 x 15 x 15 mm³). The lower part of the inoculates is plunged in vermiculite kept constantly humid by water containing a selective fungicide. After twelve weeks of exposure in non sterile conditions, in a green house with constant temperature around 20°C, the test specimens are then submitted to a static bending test until fracture. The comparison of the fracture-stress between control test specimens and the specimens exposed to wood rotting basidiomycetes permits to evaluate the resistance of the studied materials against fungal decay.
L N Trong
Are fungal cellar tests really necessary?
1989 - IRG/WP 2333
During the past decade the range of methodology used to evaluate wood preservative potential has significantly expanded. At the forefront of these new tools available to the scientist·is the fungal cellar. This technique, as currently applied, involves the exposure of treated and untreated samples to conditions of moisture and temperature which ensure optimum fungal attack. By comparison data with that obtained on similar preservative systems in conventional stake tests, acceleration factors for predicting performance have been developed. This discussion paper examines the philosophy influencing the development of fungal cellar testing, and provides an alternative viewpoint.
J N R Ruddick
Isolation and identification of the fungal flora in treated wood
1976 - IRG/WP 144
J F Levy
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.
Defining fungal decay types - Final proposal
1988 - IRG/WP 1355
The term soft rot is proposed for all forms of decay caused by Ascomycetes and non-basidiomyceteous Fungi imperfecti. The terms brown rot and white rot should be used only for decay caused by Basidiomycetes. Brown rot is characterized by extensive depolymerization of the cellulose and limited lignin degradation. White rot is characterised by significant degradation of the lignin component in wood.
Targeting fungal proteinases to prevent sapstain on wood
1995 - IRG/WP 95-10097
Discoloration of wood, caused by a variety of sapstaining fungi, leads to periodic losses in the Canadian lumber export industry. Proteolytic enzymes are thought to be necessary for retrieval of nitrogen during fungal growth on wood. The major extracellular proteinase of Ophiostoma piceae, a representative sapstaining fungus, was purified to homogeneity and its inhibition pattern characterised. Classic serine proteinase inhibitors inhibited the activity of the purified proteinase in a dose-dependent manner. Several chelating agents, detergents, heavy metals and PQ-8, a currently used commercial antisapstain formulation, also caused a reduction in proteolytic activity in vitro. Selected inhibitory compounds were then tested for their effect on growth of Ophiostoma piceae in artificial media and on wood. Heavy metals and several chelators inhibited growth on media containing protein or inorganic nitrogen, suggesting that they were toxic to the fungus rather than specific to the proteinase. However, chymostatin and PQ-8 did appear to be specific proteinase inhibitors. These products caused a decrease in growth on a protein-supplemented medium which induces proteinase production, but had little effect on growth on medium containing inorganic nitrogen. Visual assessment of lodgepole pine sapwood samples inoculated with Ophiostoma piceae also identified PQ-8 as an effective inhibitor of fungal growth. Other pure chelators and serine proteinase inhibitors did not perform well on wood. While some compounds showed promise in these tests, definitive testing and commercial application are constrained by the current lack of stable, cheap, non-toxic, specific serine proteinase inhibitors.
L D Abraham, D E Bradshaw, A Byrne, P I Morris, C Breuil
Fungal defacement of water-stored softwoods
1993 - IRG/WP 93-10009
Sapstain, mould and basidiomycete defacement of untreated sawn boards of Scots and Corsican pine was recorded during a 14 week field trial. Boards were cut from freshly felled logs and from logs previously maintained under water sprinklers for 6 months and ca. 4 years. The incidence of sapstain defacement or the freshly felled wood was very servere aftcr 2 weeks and remained so throughout the board trial. Fungal defacement of wood previously stored under sprinklers for 6 months was progressive and was severe by 14 weeks. In contrast, the level of defacement of boards from long lerm water-stored logs remained very low after 14 weeks exposure. The marked differences in susceptibility to fungal infestation of boards from freshly felled and water-stored logs are discussed in terms of wood sugar levels and the bacterial populations present in the wood.
M A Powell, R A Eaton
Efficacy of some extractives from Pinus heartwood for protection of Pinus radiata sapwood against biodeterioration. Part 1: Fungal decay
1995 - IRG/WP 95-30072
Chemical compounds thought to contribute to the natural durability of heartwood of Pinus spp. were either chemically synthesised in the laboratory or extracted from the heartwood of Pinus elliottii or Pinus caribaea. These compounds included the stilbenes, pinosylvin and its mono- and di-methyl ethers, and the flavonoids, pinobanksin and pinocembrin. Small blocks of Pinus radiata sapwood were impregnated with methanolic solutions of pure compounds or heartwood extracts, to a range of retentions extending above and below the concentration of each compound known to occur in the heartwood of Pinus spp.. Fungicidal efficacy of these compounds has been evaluated by exposure of treated blocks to pure cultures of a white and a brown rot, in addition to an unsterile soil test.
M J Kennedy, J A Drysdale, J Brown
Susceptibility of angiosperm sapwood to white-rot fungal colonization and subsequent degradation: a hypothesis
1997 - IRG/WP 97-10211
It has long been recognized that angiosperm sapwood in nature is relatively easily and preferentially degraded by white-rot fungi. This susceptibility to white-rot fungi is generally believed to be mainly caused by the structure and concentration of angiosperm lignin. However, an explicit explanation as to why lignin structure makes a particular wood vulnerable to white-rot colonisation and subsequent degradation has apparently never been given. We propose that free phenolic groups in wood, such as those present in the lignin or heartwood extractives, can act as free radical scavengers (antioxidants) which disrupt the various white-rot free radical degradative mechanisms. Consequently the presence of a relatively high free phenolic "density", such as that present in gymnosperm sapwood or angiosperm heartwood, may inhibit white-rot degradation. Conversely, white-rot fungi may find wood with a relatively low free phenolic content, such as angiosperm sapwood, easy to colonize. The complex structure of angiosperm wood, in which different cell types have different amounts and types of lignin -- and consequently different levels of free phenolic "densities" -- influences the susceptibility of angiosperm wood to initial white-rot colonisation and, perhaps, also the subsequent decay rate. In addition to the free phenolic ``density" other factors, some as yet unknown, undoubtedly also affect the decay resistance of a particular wood.
T Schultz, D D Nicholas