Your search resulted in 845 documents. Displaying 25 entries per page.
Degradation of Carbon-Based Preservatives by Black-stain Fungi
2010 - IRG/WP 10-30533
Some black-stain fungi are known to exhibit resistance to carbon-based preservatives. However, the cause of this resistance is unclear. The fungi may have mechanisms to tolerate these chemicals, or they may be able to degrade and detoxify them. Fungi capable of degrading carbon-based preservatives are of interest for possible bioremediation of carbon-based preservative-treated wood at the end of its service. Moreover, such fungi could potentially facilitate the colonization of carbon-based preservative treated wood by decay fungi. Two strains of Aureobasidium pullulans and two strains of Epicoccum purpurascens were evaluated for their ability to degrade three commonly used carbon-based preservatives: propiconazole, tebuconazole, and DDAC. At low and medium concentrations propiconazole and tebuconazole were found to be vulnerable to degradation by one of the Epicoccum purpurascens isolates. Where biocides are needed to control the growth of black-stain fungi on wood, a combination of biocides with different chemistries should be used to minimize the risk posed by resistant strains.
R Stirling, P I Morris
Black-stain Resistant Acrylic Latexes for Wood Coatings Applications
2017 - IRG/WP 17-40786
Translucent coatings on wood in exterior applications often fail due to photodegradation and colonization by black-stain fungi and require frequent refinishing. This limits competitiveness with alternative materials. In this project, it was hypothesized that an effective dispersion of inorganic nanoparticles will provide a translucent coating with long-term resistance to black-stain fungi. Functionalized silver nanoparticles with a mean particle size of 12 nm were incorporated in acrylic polymer particles by miniemulsion polymerization. This polymerization technique has been selected over the traditional emulsion polymerization to encapsulate inorganic particles into polymer particles and prevent the agglomeration of inorganic nanoparticles. In previous work, it was found that latexes containing silver nanoparticles showed antifungal activity against Epicoccum nigrum, and a mix of Penicillium funiculosum and Aspergillis niger at low silver concentration (0.1% m/m) (Boivin, Ritcey and Landry, 2015). Based on these results, acrylic latexes containing different concentrations of silver nanoparticles were mixed with a commercial acrylic resin. The formulations were applied on ponderosa pine (Pinus ponderosa) sapwood and fungal resistance was evaluated against three species Aureobasidium pullulans, Sclerophoma pityophila and E. nigrum. Latexes with concentrations of silver nanoparticles as low as 0.03% were able to control S. pityophila and E. nigrum, while higher concentrations were needed to control A. pullulans.
G Boivin, A M Ritcey, P I Morris, V Landry
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
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
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.
Blue-stain fungi (Ceratocystis spp.) found in Spain on pine woods
1989 - IRG/WP 1410
So far, there is only a very limited reported description of the different Ceratocystis spp. present on fresh wood in Spain. So, the main goal of this work has been the identification of species of this genus causing blue-stain on Pinus pinaster A. Ait. and Pinus sylvestris L. woods. We have also investigated the relationship between the species found and their propagation vectors (insects and wind). Finally, we have determined the growing velocity of two of the most representative species found and the presence or absence of degradative enzymatic activities.
M T De Troya, A M Navarrete
Relationship between stacking, location and antisapstain preservatives on visible degrade of Eucalyptus regnans and Pinus radiata boards
1999 - IRG/WP 99-20162
An antisapstain trial was established at a Eucalyptus hardwood sawmill in Victoria, Australia. The trial incorporated two commercial formulations of antisapstain preservatives, used at four different concentrations on both hardwood (Eucalyptus regnans F. Muell) and softwood (Pinus radiata D. Don) boards. The trial also utilised different stacking methods (block-stacked, sticker-stacked, and block-stacked and wrapped in black plastic) and included replicates placed both outside in the drying yard, and inside under cover from the elements. The variation in stacking methods and in location was used to provide a variation in the fungal hazard. Worst degrade (mean of 83% at 36 weeks) was obtained for the hardwood block-stacked outside and wrapped in black plastic. Lesser extents of degrade were obtained for sticker-stacked hardwood outside (4.3%) and sticker-stacked hardwood under cover (1.2%). Degrade of softwood was less than that of hardwood under all conditions. Statistical analysis of the trial indicated that the probability of any individual hardwood board deteriorating outside was nearly 4 times greater than for a board kept undercover. In addition, the probability of degrade of a hardwood board which was block-stacked and wrapped in black plastic was 3.4 times that of a hardwood board which was block-stacked but not wrapped, which in turn was 10 times that of a hardwood board which was sticker-stacked. The probability of degrade in untreated hardwood timber was 20 times that of degrade in preservative-treated hardwood timber, with variations in preservative concentration having an insignificant effect. Over all conditions the probability of hardwood timber deterioration was 5 times that of the softwood. The results of this trial confirmed that timber stored closely stacked and under poorly ventilated conditions suffered a higher visible degrade, as expected for sapstain fungi. However, although preservatives effectively reduced visible degrade under all storage conditions and at all concentrations tested, selection of correct storage conditions was also an important part of minimising degrade.
J Snow, P Vinden, S M Read
Tentative method of testing wood preservatives against blue staining
1977 - IRG/WP 259
The blue stain of sawn wood is still a real problem in Poland. Although a preservative based on sodium orthophenylphenoxide has been introduced into sawmill practice, and the technology of wood protection developed with it, new information has been obtained concerning blue stain in wood material destined for export. In order to select new chemicals or to improve the effectiveness of the ones in current use it is necessary initially to carry out laboratory tests of the prepared chemicals to determine their efficiency.
E Tarocinski, O Lewandowski, M H Zielinski
Characterisation of growth and stain of different groups of sapstain fungi on lodgepole pine
1999 - IRG/WP 99-10326
Canada is the world's largest exporter of softwood lumber. These softwood shipments are susceptible to a variety of wood-inhabiting fungi that can lead to sapstain discolouration, which in turn decrease the product value. Furthermore, the presence of these microorganisms may be unacceptable to the importing countries. The objective of this work is to assess the sapstaining capability and basic nutrition of thirty-four fungi isolates representing nine species that were isolated from sawmills across western Canada. The isolates were infected onto fresh lodgepole pine billets and assessed for staining ability, longitudinal growth, host-nutrient consumption, and host viability. The results indicated that the most aggressive saptain species on fresh logs was Ceratocystis coerulescens, followed consecutively by Leptographium spp, Ophiostoma minus, O. piliferum, O. piceae, Ophiostoma spp (D and E) and Aureobasidium pullulans. Preliminary HPLC analysis of soluble sugars indicated that mannose was the free monomer carbohydrate of choice for most of the staining fungi, followed by glucose. Arabinose and galactose were not well utilised. Gas chromatography of infected wood extracts that Leptographium sp. and C. coerulescens significantly reduced the triglyceride fraction.
C Fleet, C Breuil, A Uzunovic, A Byrne
Detection of semi-quantitative and qualitative enzymatic activities of blue-stain fungi
2000 - IRG/WP 00-10347
Blue-stain, produced in forests, continues to be a problem in countries of moderate climate. In forestry, in certain geographical areas of Spain, it has been observed that anti-sapstain products have not always been efficient, as their fungicidal effectiveness varies on occasion, depending on the species of wood and microbiota that exist in the region. It is not always easy to identify the species causing this damage. Therefore, the object of this study was the grouping of diverse isolates according to the detection of simple enzymatic activities, following a simple and rapid method of application such as API-ZYM. 36 strains of Ceratocystis spp, isolated from divers species of Pinus spp., have been tested. The results were contrasted with the activities detected in the same conditions in Pullularia pullulans and Sclerophoma pityophila. To do this, these strains were inoculated in culture broths with a basic saline Eggins and Pugh medium, to which 1% sawdust of Pinus sylvestris was added in one trial. Another test was made with a mixture of the most frequent monosaccharides in woody cell-walls (glucose, mannose, galactose, arabinose, and xylose) at 1%. After 20 days of incubation, the extracts were centrifuged, and inoculated in microtubes series of API-ZYM. The analysis of the principal components, carried out with the results obtained, showed that the sawdust induces enzymatic activities implicated in the degradation of polysaccharides such as in a-mannosidase, a-galactosidase, b-glucuronidase, b-glucosidase and b-galactosidase, which appeared as the most weighty specific factors in the dispersion of data on the first two principal axes. Different strains of Ceratocystis also showed similar or greater activity than those of P. pullulans and S. pityophila, which suggests that the latter might be more virulent than the rest of the strains assayed.
M T De Troya, F Llinares, D Muñoz-Mingarro, M J Pozuelo, N Acero, C Rodríguez-Borrajo, A M Navarrete
Effects of some essential oils on wood destroying organisms
1993 - IRG/WP 93-10047
Three wood destroying fungi: Botryodiplodia theobromae Pat. (stain), Gloeophyllum sepiarium (brown rot), and Pycnoporus sanguineus (white rot) were exposed to six plant essential oils: the peppermint, kaffir lime or leech lime, lavender, tarragon, holy basil, and the eucalyptus. The peppermint oil showed most effective to inhibit fungal growth, while eucalypus oil was the least effective. The other oils inhibition rate varied according to the species of fungi. In the experiment of the powder post beetles Heterobostrychus aequalis Waterh., the insects were killed within three days in the oil of tarragon, eucalyptus and holy basil, while in lavender oil they could live to ten days the same as controls. But on the contrary in the oil of peppermint and kaffir lime, some of them could even lived longer than the controls.
K Atisongkroh, C Anantachoke, P Lekuthai, S Pensook, T Kittirattrakarn
Antagonistic effect of some mycorrhiza fungi as biological control of blue-stain
1987 - IRG/WP 1314
This report discussed the possibility of using some mycorrhiza fungi as biological control of blue-stain. The results show that new bio-technological possibilities are opening, because, by cultivating antibiosis fungi in fermentor, it is possible to prepare extracts which can then be used as the natural preservative to control the blue-stain in wood.
Wood extractive concentration and sem examination of pretreated southern yellow pine wood chips with blue-stain fungi for mushroom production
2001 - IRG/WP 01-10407
Mushroom-producing white-rotting basidiomycetes either do not colonize or else colonize very poorly on freshly prepared southern yellow pine wood chips. This study evaluates the resinous extractive content of southern yellow pine before and after treatment with colorless mutant blue-stain fungi. The blue-stain fungi penetrate into the sapwood of southern yellow pine and utilize nonstructural resinous extractives, simultaneously reducing the total resinous extractive content. Scanning electron microscopic examination showed that heavy mycelial growth with good sporulation occurred on the surface of wood chips within 2 days and in parenchyma cells within 6 days. Ophiostoma spp. removed 61.1% to 99.9% of the extractives from the southern yellow pine wood within a period of 4 to 5 days. We conclude that white-rot basidiomycetes can easily colonize and produce fruiting bodies on treated southern yellow pine wood wastes.
S C Croan, J Haight
Fungicidal properties of boron containing preservative Borosol 9
2004 - IRG/WP 04-30348
The fungicidal properties of new boron containing wood preservative Borosol 9 is described in this paper. These properties were of particular interest as this new boron containing preservative, exhibit very good performance against wood damaging insects. But because the tested boron formulation contain also nitrogen compounds, we wanted to verify if nitrogen as a nutrient could promote growth of wood rotting and blue stain fungi. Fungicidal activity of the boron based wood preservative Borosol 9 was evaluated according to the standard EN 113 procedure. Samples made of Norway spruce were brushed two times with 10% aqueous solution of Borosol 9, air dried, steam sterilized and exposed to the following wood rotting fungi: Coniophora puteana, Gloeophyllum trabeum and Lentinus lepideus. After 16 weeks of exposure the specimens were isolated and their mass losses were determined. After this respective period, the treated wood samples lost on an average less than 1 % of their initial mass. Parallel to this experiment, blue stain testing according to the EN 152-1 procedure was performed. Specimens brushed with Borosol were for six weeks exposed to blue stain fungi Aureobasidium pullulans and Sclerophoma pithyophila. After testing period the specimens were isolated and anti blue stain efficacy was determined visually. Both tests showed that Borosol 9 has fungicidal properties. Preservative, containing the boric acid - alkanolamine complex did not enhance fungal decay or growth. On the contrary, they showed high activity against wood decay and blue stain fungi.
G Babuder, M Petric, F Cadež, M Humar, F Pohleven
Variation in infection rates of blue-stain, mould and white rot tropical fungi on mixed light Malaysian woods
2000 - IRG/WP 00-10334
The modified 3-week FRIM laboratory method for screening of anti-sapstain formulations against three representative tropical fungi causing blue-stain (Botryodiplodia theobromae), mould (Paecilomyces variotii) and white rot (Schizophyllum commune) infection of sapwood species was used to examine the relative resistance of the sapwood of eight mixed light Malaysian woods, Scots pine (Pinus sylvestris), medium density fibreboard produced from Rubberwood (Hevea brasiliensis) and the heartwood of Sentang (Azadirachta excelsa), to infection by these organisms. After 21 days it was found that Ramin (Gonystylus spp.), Rubberwood, Mersawa (Anisoptera sp.), Ludai (Sapium spp.), Yellow meranti (Shorea spp.), Scots pine and Jelutong (Dyera costulata) were highly susceptible to the pooled combinations of blue-stain, mould or white rot infection often sustaining >50% overall mean fungal coverage or when at least one of the infection types has reached maximum mean coverage (75.5%) of the wood samples. However, the Rubberwood-based fibreboard, and particularly Sentang, and the softwood Agathis spp. from Kelantan (trade name: Damar minyak) and Sarawak (trade name: Bindang), were relatively moderately susceptible to infection, sustaining between 9 and 47% overall mean fungal coverage after 21 days, or even considerably less susceptible (5 - 20% overall coverage) after 14 days. There was absence of both blue-stain and white rot fungal growth on all samples dipped in a low (0.03%/0.03%) fungicide concentration of a MBT/TCMTB anti-sapstain formulation. Such laboratory test results could have significant implications to field or industrial sapstain control of sapwood timbers concerning the lag time between tree felling and anti-sapstain treatment and seasoning.
A H H Wong, S Ahmad
Preventive effectiveness of petroleum derivatives against blue-stain fungi. Part 2
1993 - IRG/WP 93-30001
Solvex-Tar, a product derived from the distillation of petroleum could be suitable for the treatment against blue-stain fungi in wood used in exterior carpentry, due to its effectiveness as a fungicide. The aim of this work has been to optimize the application of this product, modifying it as necessary, so as to improve its physical characteristics without interfering with its preventive effectiveness. To this end, six different Solvex-Tar based products have been tested, adding to them alkyd resin in different proportions, and toluene as solvent. The results demonstrate that the modification tested avoid its incompatibility with traditional coatings, decrease the viscosity and maintain its effectiveness against blue-stain fungi of wood in service.
E Sanchez, M T De Troya, A M Navarrete, A Guijarro
Preventive effectiveness of petrol derivatives against blue-stain fungi
1992 - IRG/WP 92-3716
A possible application of fractions obtained on petrol pyrolysis is their use as a wood preservative against wood-decay and sap-stain fungi. From two of these fractions were prepared three different products (ST, STL and SST). The aim of this work has been the possibility of utilizing these products in the treatment of wood used for external joinery, determining their effectiveness against blue-stain fungi and their compatibility with existing surface coatings. Test blocks of Pinus sylvestris and Pinus pinaster were used, treated with a brushed application of the above products, and then two different kinds of coating. The wood blocks were then exposed to 3 months of weathering. After this time they were placed in contact with pure cultures of Pullularia pullulans and Sclerophoma pityophila in sterile conditions, for 6 weeks. After the period of weathering the degree of varnish adherance was evaluated. The effectiveness of the preservatives was assesed by determining the penetration depth of the hypha into the wood face. The results obtained revealed that only ST and SST were effective against blue-stain fungi for wood in service, whereas the degree of compatibility with the coatings varied.
A M Navarrete, M T De Troya, E Sanchez, A Guijarro
Which fungi should be included in the laboratory evaluation of anti-stain chemicals?
2001 - IRG/WP 01-20236
Test fungi for efficacy tests of anti-stain formulations were selected based on the assumptions that test fungi should be fungicide-tolerant antagonists and fungi resistant to both fungicides and fungicide- tolerant antagonists, and such fungi should be re-isolated from treated samples with the highest fungicidal concentration used for laboratory evaluation of fungicides. This paper discusses the results of the study performed to assess the above assumptions using the fungi re-isolated from treated samples used for the laboratory efficacy tests of NP-1 Plus against all fungal isolates from green radiata pine logs.
Hyung-Jun Kim, Jae-Jin Kim, Gyu-Hyeok Kim
Laboratory screening to determine the preventive effectiveness against blue stain fungi and moulds
1991 - IRG/WP 3677
This paper reports results of preservative treatment and leaching experiments, using borax, polybor and boracol 20, on small wood blocks of English oak and American pitch pine heartwood. Earlier experiments on the performance of various biocides as possible additives to bilgewater to prevent fungal decay of shipping timbers had suggested that some formulations of boron might be associated with physical changes to specific types of timber. Since samples of oak and pitch pine were to be supplied for remedial work on the historic ship RRS Discovery it became important to investigate more critically the effects of boron on such timbers. Variable factors investigated in this study included temperature, sample type, soaking time in preservative and time of leaching. Weight changes and dimensional changes were measured. Preliminary results indicate that there was little effect, at 10°C, on block weight or dimension. Some changes were found at 45°C indicating that the results obtained in earlier experiments may be unrepresentative of those which might be obtained when the biocide is used under service conditions.
M T De Troya, A M Navarrete
Association of contents of nitrogen and sugars in rubberwood (Hevea brasiliensis) clones with susceptibility to sapstain by Botryodiplodia theobromae, Aureobasidium pullulans and Aspergillus niger
1999 - IRG/WP 99-10307
The purpose of this study was to determine if nitrogen and sugar contents in rubberwood from three selected varieties (clones) rubber trees would affect the rate of colonisation by Botryodiplodia theobromae (a tropical sapstain fungus), Aureobasidium pullulans (a temperate sapstain fungus) and Aspergillus niger (a common mould fungus). Sapstain growth was rated daily until at least 50% mycelial coverage was achieved for 40x20x5mm3 samples from three rubberwood clones (GT1, PB217 and RRIM600) inoculated with the test fungi and incubated in a humidified petri dish assembly under aseptic conditions. All samples had more than 50% coverage of mycelium after 9 days of incubation. The results indicate that the nitrogen content of clone RRIM600 (1.06lmg/g) was significantly higher when compared to that of clone GTI (0.73mg/g) and clone PB217 (0.78mg/g). After oven drying (45°C), clone PB217 contained significantly higher amounts of fructose (5.55mg/g), glucose (2.30mg/g) and total sugar (13.15mg/g), as compared to clone GTI and RRIM600. Clone GTI had the lowest fructose (0.23mg/g), glucose (0.14mg/g), sucrose (2.20mg/g) and total free sugar (2.56mg/g). RRIM600 however had the highest amount of sucrose. B. theobromae spread significantly faster on RRIM600 (4.3 days when >50% mycelial coverage is achieved) than PB217 (5.6 days) or GTI (5.8 days) which is associated with the overall higher nutrient availability in clone RRIM600. Light sanding (down to 1-2mm depth) of sapstain infected samples revealed that deep sapstain typical of B. theobromae remained in the wood, contrasting with the absence of stain by A. pullulans and A. niger (both are typical superficial stainers) in the sanded material.
A J Ashari, J W Palfreyman, A H H Wong
Fungi causing sap stain in wood
1980 - IRG/WP 199
The present paper is a revised edition of former Document No: IRG/WP/125. It contains some additions and an explanation of terminology, as was suggested at a previous meeting of the Group. The paper is a compilation based mainly on available literature. Some of my own unpublished results have been added together with other unpublished data which have been received from the Bundesanstalt für Materialprüfung in Berlin and from colleagues at the Department of Forest Products, Swedish University of Agricultural Sciences, which are acknowledged with thanks. Fungi, described in the text, have been selected according to the following principles: a) the most common and important blue stain fungi, b) less common fungi which have been found in several countries or on several host trees, c) fungi which seem to be of minor interest as blue stain fungi, but which have been used recently in experimental work considering their physiological characters, susceptibility for toxic substances etc. The author regrets that this paper does not cover the tropical fungi, as there have been only a few notes about these in reviews and as the original papers have not been available to our library.
Invasion and colonisation of bamboo culm material by stain and decay fungi
2002 - IRG/WP 02-10453
Two distinct stages of the fungal infection of bamboo culms can be identified: entry into the culm itself (invasion) and further colonisation by spread within the culm wall tissue. This laboratory study aimed to characterise different invasion strategies of a variety of fungi. Well-known isolates of white- (Coriolus versicolor, Schizophyllum commune), brown- (Coniophora puteana, Gloeophyllum trabeum, Poria placenta), soft-rotting (Chaetomium globosum) and stain fungi (Lasiodiplodia theobromae) were used as test organisms in culm wall material of Moso Bamboo (Phyllostachys edulis). By giving the fungus defined “entrances” into the specimen and by introducing a “baiting” method, routes of entry taken by fungal hyphae during infection of the culm tissue were investigated using light and scanning electron microscopy. he results show clearly that typical bamboo decay fungi such as S. commune and C. globosum can infect the fresh, undamaged culms via the dense outer epidermis if growth conditions are optimal. No part of the culm was identified as a barrier. Small bore holes in the epidermis, caused by penetrating hyphae were identified using scanning electron microscopy. It is proposed that this was the main pathway of entry into the culm tissue.
G Kleist, I Morris, R J Murphy
Effect of volatiles from bacteria and yeast on the growth and pigmentation of sap-stain fungi
2000 - IRG/WP 00-10331
Sapstain fungi cause deterioration of wood due to colonisation by pigmented hyphae but without producing significant strength losses. This is due to the production of melanin in the fungal cell walls of the staining fungi. Any biological control strategy targeted against this type of deterioration would therefore be considered successful if it inhibited either fungal growth or pigment production. Previous work has established that specific bacterial and yeast isolates selected on the basis of agar screening studies could significantly reduce levels of staining in wood block tests. This paper presents the results of a study to examine the role of volatile organic compounds (VOCs) produced by three bacterial and three yeast isolates on the growth and pigment production by a range of five sap-stain fungi on three media types. Results were variable and dependent on media type. Of all combinations tested Sclerophoma pityophila showed greatest levels of inhibition when exposed to bacterial VOCs when grown on tryptone soya agar. On some occasions, although no significant inhibition of growth was produced, the level of pigmentation of the sapstain colony as measured using image analysis equipment was significantly reduced compared with corresponding controls. The implications of this work for the biological control of sapstain fungi are discussed.
A Bruce, R E Wheatley, S Verrall
The influence of fungi causing blue – stain on absorptiveness of Scotch pine wood
2005 - IRG/WP 05-10565
The blue-stain fungi cause discoloration of the wood. In the course of their development in wood may have an effect on wood structures and properties influenced on its use value. Investigation has been undertaken to clear the influence of blue-stain fungi on wood absorptiveness as indicators for the wood ability to impregnation with water diluted wood preservatives. The wet sapwood samples of fresh cut Scots pine (Pinus sylvestris L.) were infested with pure cultures of fungi: Ceratocystis penicillata (Grosm.)C.Moreau, Cladosporium herbarum Pers. ex Fries, Discula pinicola (Naum.) Petr. or their mixture. The samples of the wood were than exposed into thefungi action through 1, 3 and 12 month period. The absorptiveness of blue stained wood samples and their twin control samples were determinate and compared after each incubation period. The absorptiveness of the stained wood increased greatly particularly after 3 and 12 month of being infected by fungus or fungi. The mean increase of infected wood absorptiveness was great. It reached several dozen percent more than control wood. Such differences showed on grater ability of blue-stained wood to impregnation with water diluted wood preservatives than control wood not infested by the blue-stained fungi.
Black Stain of Western red-cedar by Aureobasidium pullulans and its Relationship with Tropolone Depletion
2005 - IRG/WP 05-10564
Western red-cedar is valued for its natural durability conferred by fungicidal tropolone chemicals. However, weathered surfaces of WRC products are still susceptible to ‘black stain’ caused by fungi such as Aureobasidium pullulans. The effect of weathering on the tropolone content of heartwood was characterized and correlated with the ability of this fungal species to colonize the same weathered surfaces. UV plus water spray severely reduced tropolone content but did not lead to increased fungal colonization compared to un-weathered wood. When WRC was treated with UV only, the tropolone content was less affected but the fungal colonization increased significantly. A.pullulans exhibited high tolerance to the tropolone β-thujaplicin in vitro; thus loss in tropolone content may not be required for colonization. In addition to UV resistance from melanization and ability to use lignin breakdown products as a carbon source, resistance to tropolones may confer considerable competitive advantage to A.pullulans growing on WRC exposed to weather. The application of water spray most likely washed away products of lignin photo-degradation, leaving the wood surface void of accessible carbon sources which resulted in decreased colonization.
R Chedgy, R Daniels, P I Morris, C Breuil