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Which fungi cause sapstain in Canadian softwoods?
1998 - IRG/WP 98-10285
The Canadian forest products industry suffers considerable losses in revenue due to fungal stains. There is an increased awareness that more complete knowledge about the causal organisms might help solve the problem. A first step was to initiate a thorough survey of bluestain fungi in Canada. Systematic sampling was done at seven selected sawmills in six Canadian provinces. In summer 1997 fresh logs and lumber were set aside a month prior to sampling for fungi. Five commercially important softwoods, Abies balsamea, Picea mariana, P. glauca, Pinus contorta and P. banksiana were included in the studies. The objectives were to identify the main discoloring fungi and subsequently to evaluate the genetic diversity among isolates of the fungal species found to predominate. Fungi isolated from the experimental timber were identified based on their morphological characteristics, measurement of their growth rates, and by testing their mating compatibility with known mating types. A substantial number of isolates and a variety of species were obtained. Most frequently isolated were species from the genus Ophiostoma. A more diverse range of fungi was found in logs than on lumber. Preliminary data suggest that some species tend to predominate on certain wood species and in certain geographic regions but none appeared to be exclusive.
A Uzunovic, Dian-Qing Yang, P Gagné, C Breuil, L Bernier, A Byrne

Influence of bark damage on bluestain development in pine logs
1997 - IRG/WP 97-10197
Mechanized harvesting of conifers can lead to extensive bark damage, with the resulting wounds providing suitable entry points for bluestain fungi that are not associated with bark beetle vectors. However, the amount of bluestain colonisation can vary greatly between the different types of wound. To evaluate the effect of wound type seven different types of wounds were artificially created on freshly felled logs of Corsican pine. These ranged from barely visible punctures, to the removal of large strips of bark, simulating typical harvester damage. The logs were left in the field exposed to natural inocula of wood degrading fungi and assessed after 6 and 12 weeks. Results indicated that surface area of injury was not the best parameter for predicting the rate and extent of staining. Minor disruptions of the bark e.g. crushing and punctures, were sometimes associated with substantial amounts of stain development. Wounds with flaps of loosened but still attached bark were especially susceptible to bluestain colonization, but additional damage to exposed wood surfaces did not result in more stain. Stain development was strongly associated with the edges of wounds where the bark and exposed wood met. Excluding potential bluestain vectors such as bark beetles and weevils by enclosing the logs in netting did not markedly reduce stain, suggesting that micro-arthropods such as mites play an important part in disseminating bluestain fungi to wounds produced during harvesting and log extraction.
A Uzunovic, J F Webber, D J Dickinson

Variation in Canadian bluestain fungi: Tolerance to DDAC and DOT
1999 - IRG/WP 99-10303
Bluestain in Canadian wood products results in significant and unpredictable losses each year. In order to develop rational methods to eliminate or reduce the sapstain problem, a more complete knowledge of the causal organisms must be gained. This includes a knowledge of the variability in tolerance of different fungal species and strains to commercially used chemicals. In British Columbia, the majority of anti-sapstain chemicals are based upon the quaternary ammonium compound DDAC, either as the sole active ingredient or in formulation with co-biocides such as disodium octaborate tetrahydrate (DOT). Ten strains each of the three most prominent blustain fungi found in Canada (Ophiostoma piceae, Ophiostoma piliferum, and Graphium (species C)) were evaluated for their tolerance to DDAC and DOT. The main findings showed there was little or no variation in the tolerance to the chemicals within the strains of each species tested. In the screening tests it was found that DDAC was less effective in inhibiting fungal growth than DOT. However, further examination revealed that the ineffectiveness of DDAC was due to interactions with the media components - a reminder that care must be taken when evaluating results especially with surfactants such as DDAC. Additional work with other sapstain control chemicals is underway.
J Dubois, A Byrne, J E Clark, A Uzunovic

Decrease in the mechanical resistance of blue stained and "orange stained" Pinus radiata wood
1999 - IRG/WP 99-10313
It is recognised that sapwood attacked by Ceratocystis pilifera increases its permeability to pressure preservative treatments. Since hiphae not only utilise pits, but also the cell wall for crossing from one cell to another, the mechanical resistance of the stained wood might be affected. The orange colour very commonly present in Pinus radiata logs heartwood under water sprinklers, has not received enough attention and among others, its effect on the mechanical properties of timber is not known. Lumber with no visible bluestain, 50% stained and totally stained was commercially obtained, then it was dried to 12% moisture content and cut for testing its bending strength according to the Chilean standard NCh 987. The following mechanical tests were carried out on "orange stained" heartwood samples taken from the central part (without pith) of Pinus radiata logs. Static bending, compression parallel to the fibre, traction perpendicular to the fibre and shear parallel to the fibre were measured according to the Chilean standards NCh 987, 973, 975 and 976 respectively on orange stained and sound wood samples. Bending strength of 50% bluestained wood samples was 29% lower than that of sound wood samples. The bending strength fluctuation of 50% to 100% bluestained wood samples was 29% lower than that of sound wood samples. In orange stained wood samples the mechanical test results did not show significant difference in the 4 measured and standardised properties between orange stained and sound samples. Considering non-standardised data the bending MOE and the traction MOR were lower in orange stained wood. The evenly fully developed orange colour of the samples did not mean deterioration of the cell walls and this was confirmed under microscopic observations of microtomed material. A few hiphae were found and coloured matter was more often observed in parenchymatic cells.
M C Rose, L Reyes, J Alvarez, A Andaur, C Beltran, D Rivera

The effect of primary blue-staining fungi on the strength properties of Scots pine sapwood
2004 - IRG/WP 04-10515
The fungi action may have influence on wood properties especially Basidiomycotina fungi causing wood decay. The investigation of influence of fungi causing mainly wood discoloration and disfigurement on wood properties is still in development process. There were determined the differences between the bending strength, the compression along the grains and impact strength of control and blue stained sets of Scots pine (Pinus sylvestris L.) twin sapwood samples. The one part of each twin sapwood samples sets was exposed for 1, 3 or 12 months to the action of pure culture of blue staining fungi Ceratocystis penicillata, Cladosporium herbarum, Discula pinicola or their mixture while the second part of sets was control samples. Research showed that the changes in wood strength properties were dependent on the fungi action period and to get worse with the fungi action prolongation. The statistically significance of decreasing of sapwood properties was greater by impact strength and compression along the grains strength than by bending strength investigation. The level of decreasing the wood properties caused by blue-stain fungi during 12th months of their action was larger for impact strength (over –13%), smaller for compression along the grains strength (about –5-8%) and only very little (to –3%) and with less statistically significance for bending strength. The impact strength and compression along the grains strength appeared to be more sensitive indicators of the blue stain fungi action than bending strength.
A Fojutowski

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.
A Fojutowski

Anti-bluestain treatment developed for log cargoes stacked in subtropical conditions for export on logging ships
1995 - IRG/WP 95-30081
Subtropical environments impose conditions of temperature, humidity and rainfall which are optimal for growth of bluestain fungi. Unprotected softwoods under such conditions become bluestained three days after felling. Furthermore, intervals between harvesting and delivery to export marketplaces exceed the 30-day protection periods attributed to anti-bluestain formulations in such conditions. These constraints led to demand for an anti-bluestain formulation with performance which would satisfy customers receiving softwood cargoes in the Far East three months after harvesting in South Africa. The concentrated fungicides were formulated with agricultural adjuvants conventionally used with herbicidal sprays, with surfactants and penetrants to improve wood cover and fibre penetration by the active ingredients, and with stickers to simultaneously retard their loss by leaching. In standard 6-week and extended 12-week laboratory tests one such formulation returned ratings of zero bluestain in Pinus elliottii sapwood discs which had been drenched in water immediately after treatment, and it outperformed all other formulations compared with it. In extensive four-season field trials conducted in Zululand the formulation continued to outperform all those compared with it and provided superior protection of Pinus elliottii and Pinus patula sawlogs from bluestain for 18 weeks. Inspections of a 10,000 m³ cargo of pine sawlogs shipped to Korea and of a similar cargo of peeler logs shipped to Japan supported these findings.
A A W Baecker, M Behr, G D Shelver

The influence of causing primary blue-stain fungus Ceratocystis imperfecta on selected properties of Scots pine wood
2002 - IRG/WP 02-10425
The effects of development in wood the fungi causing blue-stain on the wood properties are not univocal. There were been undertaken investigation to clear the influence of such fungi on selected physical and mechanical properties of Scots pine wood. Wet sap wood samples of fresh cut Scots pine wood (Pinus sylvestris L.) were infested with pure culture of Ceratocystis imperfecta Mill. et Grenz and exposed into its action through 1, 3 and 12 month. The properties of the infested wood and their twin control samples were determined after each incubation period. The wood became the grey-black colour. The complete change of colour - ?E – measured by colorimetric Datacolor equipment was about 30 already after 1 month. The blue stain depth was from 1,0 mm - after 1 month to 5,0 mm (=whole cross - section) after 12 months. The absorptiveness of the stained wood greatly increased after 3 and 12 month of being infected by fungus. There was a tendency to drop the compression along the grains of blue stained wood in all investigated periods, but statistically essential changes appeared after only 12 months of the fungus action (mean drop 5%). The decrease of the impact of blue stained wood was statistically essential after 3 and 12 months of the fungus action (mean drop 13%). The statistically essential decrease in strength of wood was stated also by measuring of logarithmic decrement of torsional vibrations (mean drop 6%) and modulus of torsional rigidity (mean drop 2,5%). The stated changes in blue stained wood may to influence negative on usefulness of wood.
A Fojutowski

A trial of "sour" felling to prevent bluestain by depletion of sapwood nutrients
2001 - IRG/WP 01-10404
Discoloration of conifer wood caused by bluestain causes large economic losses in Canada. Most deep stain develops in the log stage during storage or transport. In a search for control strategies that will not disrupt woodlands productivity we tested "sour" felling, termed "hagarashi" in Japan. The practice involves delaying the delimbing of freshly harvested trees. The tree continues to transpire and to respire. This could result in partial drying of the wood and/or faster depletion of sapwood nutrients needed for the growth of bluestain fungi. Field experiments were done compared sour-felled trees with ones immediately processed by a harvester/delimber. We examined the development of stain and also analyzed sapwood nutrients. The latter included lipophilic extractives, phenolics, soluble sugars, starch and total nitrogen. There was no stain in both sets of trees, attributable to unfavourably cool weather. The viability of ray parenchyma cells and the moisture content remained similar in both sets of trees. Despite being unable to show a benefit in reduced stain this work provided baseline data for the levels of the extractives in fresh and stored lodgepole pine trees. Starch was depleted to 20-30% of its original amount over the six week period, presumably as it was used by the dying tree.
A Byrne, A Uzunovic, D Minchin, C Breuil

Development of bluestain in commercially harvested logs in Britain
1996 - IRG/WP 96-10150
In Britain, mechanised harvesting of conifer forestry crops is now the preferred method of felling where terrain and access allows. However, use of mechanised harvesters can lead to excessive debarking, loosening of the bark and wood splintering with, on average, about a third of the bark removed from the more severely damaged logs. More bark has also been observed to be lost from logs harvested early in the summer (June) than later in the season (August). In an experiment which ran from June October in 1993, mechanically harvested logs with only relatively small amounts of bark damage (mean 12%) were found to be much more susceptible to attack by bluestain fungi than those processed manually, and the damaged areas were associated with extensive bluestain development around the log circumference. The most dramatic staining was produced by Ceratocystis coerulescens and Leptographium wingfieldii. Bark beetles which act as vectors of some bluestain fungi were excluded from the experimental logs, but other insect genera were found to act as casual vectors of the staining fungi. Harvester design and improved skills of harvester operators cannot significantly reduce the potential amount of blue stain degrade as significant reduction of stain only comes with the very low amounts of bark damage (0-10% of circumference) and this is practically unachievable with mechanised methods. Thus rapid delivery of logs for further processing remains the safest way of minimising the opportunity for fungal attack.
A Uzunovic, J F Webber, D J Dickinson

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

Biological Control of Bluestain - Log Field Trials in Canada
2002 - IRG/WP 02-10423
In the summer of 2000 we ran two field experiments (in Alberta and British Columbia) to test the feasibility of using an albino bluestain isolate (Cartapip97TM) to protect lodgepole pine logs from being stained by wild-type bluestain fungi. Results showed that Cartapip applied at the recommended concentration significantly reduced the amount of stain found in the Alberta trials. Cartapip applied at one-third of the recommended concentration resulted in stain that was not significantly different from that in the control logs. Tim-bor, used as a reference chemical, also significantly reduced stain but less effectively than Cartapip. In the BC trials the stain prevention effect of Cartapip appeared to be stronger in discs that had large sapwood areas. Our conclusion was that Cartapip showed promise in controlling stain in freshly felled pine logs during the first 12 weeks of storage.
A Uzunovic, D Minchin, A Byrne

Influence of the nutritional elements on pigmentation and production of biomass of bluestain fungus Aureobasidium pullulans
1997 - IRG/WP 97-10198
The effect of the carbon source and the amount of the nitrogen on the melanization and the production of mycelial mass of bluestain fungus Aureobasidium pullulans was studied by using solid state cultivations. The carbon sources used varied from easily soluble sugars to structural polysaccharides existing in lignocellulosic material. The amount of melanin was evaluated by using partial purification and the conventional measurement methods. The production of melanin was clearly dependent on the amount and quality of carbon source as well as the amount of nitrogen. A. pullulans has a high tendency to produce melanin on nitrogen poor media supplemented with easily soluble sugars (eg. glucose, sucrose, mannose and xylose). The production was restricted on nitrogen rich media. The production of melanin was totally inhibited on the media containing celluloses or lignin as sole carbon sources.
A-C Ritschkoff, M Rättö, F Thomassin

Screening method to test efficacy of fumigants against fungi and preliminary data on the efficacy of sulfuryl fluoride
2014 - IRG/WP 14-20551
Methyl bromide is being phased out and there is an urgent need to find a suitable replacement that is effective in reducing exotic pest establishments via trade in wood products. Efficacy data for established phytosanitary fumigants were mostly developed for arthropods and nematodes, and limited information exists for plant pathogens. Increased interest in developing a fast screening process for fungi has prompted this work. Small scale sulfuryl flouride fumigations were conducted in 10 L chambers at six target concentrations (40-240 mgL-1) at 20 C for 24 h against 23 fungal species. Fungi were grown on barley/grain, which was placed in borosilicate glass tubes covered on both ends with a felt cloth to allow uninhibited gas penetration while minimizing the risk of fungal contamination. This allowed simultaneous testing of numerous species/isolates followed by 100% recovery of controls and without contamination of all other isolates exposed to six target sulfuryl fluoride concentrations. Preliminary data have shown that 13 out of 23 species survived the 240mgL-1 exposure. Additional research is needed to test efficacy against more isolates, and under different temperatures and exposure times before experiments closer to field conditions are conducted.
A Uzunovic, A Mukherjee, R Mack, P Elder, S Myers