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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
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
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
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
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
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
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
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.
Susceptibility of painted wood to discolouring fungi - influence of binder, solvent and surfactant
1992 - IRG/WP 92-3714
Previous studies have shown that the basic composition of paints, without fungicide addition, can significantly contribute to the varying microbial susceptibility of painted wood. Previously, non-weathered water-borne acrylic paints applied to wood without a primer were shown to be more susceptible to mould attack than solvent-borne alkyd paints. The present study was initiated to reveal if this difference was mainly an effect of the type of binder, solvent or surfactant used. Laboratory made paints, including water-borne acrylic paints, a solvent-borne acrylic paint, a solvent borne alkyd paint and alkyd emulsion paints, with known compositions were tested. It was found that the type of binder was more important than the solvent. The use of different surfactants could lead to different susceptibility of alkyd emulsion paints on wood.
J Bjurman, C Herder
Laboratory studies on control of sapstain and mold on unseasoned wood by bacteria
1991 - IRG/WP 1493
A malt-agar and nonagar laboratory test was used to evaluate the efficacy of bacterial preparations as biological control agents against several sapwood-inhabiting fungi. Both nonsterilized and filter sterilized bacteria preparations prevented attack by the sapwood-inhabiting fungi. Streptomyces rimosus was the most effective bacteria, giving good protection, with a 1-hr soak in a filter-sterilized preparation, against discoloration in Southern Pine and sweetgum during an eight-week exposure.
T L Highley, R Benko, S C Croan
The relationship between blue-stain and bark beetles
1971 - IRG/WP 19
The attack of bark beetles on standing or in newly-felled stems provides special growth conditions to wood-inhabiting fungi. In the wood attacked by bark beetles, a specific and rich fungus flora is found, and from these fungi the economically important group of blueing fungi has been more thoroughly investigated. These fungi live on nutritive substances present in the cells, especially in the medullary rays and other parenchymatous cells. They attack lignified cell walls only to a limited extent but in the ray cells they may cause considerable destruction. Some of these fungi may attack the secondary cell walls where they develop cavities. The blueing fungi attack standing trees when their moisture content is low as well as timber at different stages of storage before it is completely seasoned. They spread very quickly both radially and longitudinally and thus they may cause rapid discolouration and considerable financial losses. The greatest losses are caused by blueing fungi which attack newly felled timber in the forest simultaneously with the infestation of bark beetles. Von Schrenk (1903) has already pointed out the relationship between the attack of the bark beetles and the blueing of the wood which at this time was thought to be caused by one fungus Ceratocystis pilifera. Later.the number of known Ceratocystis species which are, over the whole world, the most common fungi associated with the attack of bark beetles, have amounted to 80-90 at the present time, and they have been studied most thoroughly by R W Davidson (numerous papers between 1935 and 1970) in the USA. The greatest number of species has been found in North America, where the variability in host trees and in climatic conditions is greater than in North Europe.
Enzymatic study of Ceratocystis sp., blue-stain fungi on Pinus nigra
1999 - IRG/WP 99-10315
One of the main problems that the forest exploitation industry has with Pinus nigra wood is the blue-stain fungi, whose causing agent is unknown. Therefore, the objective of this work has been to study, through enzymatic tests of the isolated cultures, if these fungi infect Pinus nigra in any specific way. After the incubations, isolates of Ceratocystis were obtained. These were cultured in a saline medium with sawdust of Pinus nigra and Pinus sylvestris, which were used as reference species. At different incubation times, carboxymethylcellulase, xylanase, cellobiohydrolase, laccase and manganese peroxidase were determinated. The results obtained show that the cellulolytic enzymes and laccase have higher activity on Pinus nigra sawdust than on Scots pine, while the Mn peroxidase showed higher values on the sawdust of the latter. Likewise, the cultures were developed in the same saline base medium with different monosacarides (glucose, galactose, mannose, xylose and arabinose), and in determining the residual sugar content, a marked prefrence for the consumption of pentoses in respect to the glucose was observed. The enzymatic activity tests carried out by APY ZYM also showed qualitative and semiquantitative differences between the isolated fungi and other Ceratocystis species tested, so, in addition to the above results, this could indicate a certain specificity of these fungi for this wood species.
M T De Troya, F Rubio, D Muñoz-Mingarro, F Llinares, C Rodríguez-Borrajo, M Yuste, M J Pozuelo, J I Fernández-Golfín
The importance of blue stain attack for the colonization by wood-rotting fungi of wood not in contact with the ground
1988 - IRG/WP 1349
When used in constructions not in contact with the ground, wood has been shown often to proceed from blue stain to moulds. The appearance of wood rotting fungi is normally delayed. Solid wood artificially inoculated with the blue stain fungus Pullularia pullulans was shown to permit germination of Pycnoporus cinnabarinus basidiospores. This was demonstrated by the use of an indirect and a direct bioassay, where spores were applied directly on the wood surface. Fresh wood did not permit germination. Phenolic compounds were shown to be degraded. In in vitro cultures four other blue stain fungi and one thermotolerant mould were tested for their ability to degrade phenolic spore germination inhibitors extracted from pine sapwood. In addition, the degradation of pure phenolic compounds related to lignin were studied. A marked effect of the medium was revealed. The normal succession during colonization of wood not in contact with the ground by fungi could thereby be partly explained.
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
Growth inhibitory effects on blue-stain fungi of applied electricity fields
1996 - IRG/WP 96-10167
Exploratory laboratory experiments on the effects of electricity on two blue stain fungi Aureobasidium pullulans and Ceratocystis piceae on wood revealed that a potential gradient of 1 V/cm corresponding to a current of 15 mA (DC), applied without interruption during a 2 week experimental period, leads to an inhibition of the growth of these fungi. Germination is somewhat more sensitive than mycelial growth. Experiments also revealed that a potential gradient of 10-25 V/cm applied for 30 sec, 3 times every 24 h also inhibited the growth of Aureobasidium pullulans. The mechanism by which electricity exerts its growth inhibiting effect on blue stain fungi on wood is presently unclear.
Mycoparasitism by some white rot fungi on blue stain fungi in culture
1986 - IRG/WP 1304
When studying biological control of blue stain an interesting phenomenon of parasitism by some white rot fungi on blue stain fungi has been encountered. The majority of the 22 tested white rot fungi act parasitically upon blue stain fungi. The most interesting species among them is Bjerkandera adusta (Willd. ex Fr.) Karst., causing almost complete or complete decoloration of the hyphae of the blue stain fungi in culture on agar substrate. Obviously, complex enzyme reactions are involved; the main role probably performed by peroxidases. Bjerkandera adusta (Willd. ex Fr.) Karst., acted similarly upon blue stained wood, which was rapidly bleached.
R Benko, B Henningsson
Methods of testing anti-stain chemicals for protecting sawn timber during storage and transport
1976 - IRG/WP 273
No international standard method for testing anti-stain chemicals for protecting fresh sawn timber exists. The methods used can be divided into three types: a) Rapid screening tests for finding chemicals effective against blue-stain and mould fungi. The chemicals are tested in agar medium, in pieces of filter paper or on small pieces of wood using pure cultures. b) Laboratory tests for evaluating the effectiveness of a preservative and estimating the minimum concentration for the treating solution. Wooden test pieces of different size and artificial infection are used. c) Field tests for evaluating the effectiveness and performance of a preservative under practical conditions. The fungal infection is mostly natural. There is a need for standardisation of the method especially for the tests of type b, to be able to repeat the tests and have comparable results. The results from field tests are always dependant upon the natural conditions that vary between places and even in the same place. Besides, a field test often tries to simulate the local service conditions. However, standardisation of the techniques and of the principle of evaluation might faoilitate the conduction of tests, and the comparison of the results. In this paper, a short summary is made on the variables in the present tests, that should be subject to unification. The summary is based on literature, that is not complete. The differences in the present methods are so numerous that they cannot be discussed here in detail.
Analysis of the degradation of carbohydrates by blue-stain fungi
1990 - IRG/WP 1457
The topic of the degradative ability of blue-stain fungi literature is not clear. Many authors support the idea that those fungi don't have enzymatic capability to decay the wall of the ligneous cells. However, others have found some decay activity. In this study, we have attempted to analyze which wall cells soluble carbohydrates are metabolized by some blue-stain fungi, found in Spain. The tested fungi have been: Pullularia pullulans and Sclerophoma pityophila (wind-dispersed), and Ceratocystis huntii and Ceratocystis ips (bark beetles transmitted). This study has been realized through the determination of: the growing rate, the amount of biomass produced by these fungi and the chemical analysis of the culture media, with six different carbohydrates (glucose, mannose, rhamnose, arabinose, galactose and xylose).
M T De Troya, A M Navarrete, E Relano
Comparison of bluestain fungi growing in vitro and in vivo
1996 - IRG/WP 96-10149
Both moulds and bluestain fungi cause serious economic losses for forestry and timber processing industries and much research is aimed at finding environmentally and economically acceptable methods of control. It is especially important to study the growth of these fungi in freshly cut wood, which has been unaltered by drying or sterilisation, and which therefore resembles the substratum they would normally invade under natural field conditions. To meet this objective the growth of six sapstain fungi was compared at 20°C in freshly cut pine billets and on three types of artificial media (MEA, TWA and Pine Sapwood agar). The fungi comprised Ceratocystis coerulescens, Leptographium wingfieldii, Ophiostoma minus, Ophiostoma piceae, Potebniamyces coniferarum and Sphaeropsis sapinea. The six species varied markedly in their linear growth rate on agar media. In pine billets, they extended at different rates in longitudinal, radial and tangential directions, showing different pathogenic ability, patterns of colonisation and capacity to stain wood or kill bark. Some species appeared to be 'xylem preferring' while others appeared to colonise the phloem tissue more readily. Interestingly, the growth of Ceratocystis coerulescens in pine billets was more then two times faster than on MEA, suggesting it was strongly stimulated by the living pine tissue. In addition, there was an indication that the fungi grew more slowly in logs cut in January than in the summer.
A Uzunovic, J F Webber, D J Dickinson