Canadian wood species such as spruce and pine are difficult to treat with wood preservatives or other wood enhancing formulations due to a thin sapwood band and refractory heartwood. One method of improving penetration is by biological incising. Biological incising with Dichomitus squalens was originally developed in Austria in the 1990s to increase the permeability of European spruce prior to treatment with wood preservatives. Recently the patents on this technology lapsed. It was considered unlikely that industrial use of a European white-rot fungus would be acceptable in Canada. FPInnovations therefore conducted a screening test of a range of Canadian isolates of various white-rot fungi to identify an isolate that would be suitable for biological incising of Canadian spruce and pine. Under pure culture conditions, one isolate of Dichomitus squalens isolated from white spruce was found to greatly increase the permeability of the wood, particularly in spruce. The objective of the current study was to determine if these results could be achieved on commercial sized wood under non-sterile conditions more similar to an industrial setting. Lumber samples, 3.8 cm by 8.9 cm by 400 cm in length were incubated in plastic totes with fungal inoculum. Two isolates of fungi were tested as well as two different decontamination methods (steam and Benomyl solution) and two time frames (4 and 6 weeks). Through treatment of spruce samples (19 mm penetration) with 1.7% ACQ was achieved after six weeks incubation with D. squalens 78A (a spruce isolate). In matched samples treated with MCA, a minimum of 10 mm penetration was achieved in 90% of the samples. Strength loss in some individual samples was higher than adjustment factors for conventional incising (over 25%) suggesting that incubation time may need to be shortened. Preservative penetration was more variable in pine but permeability was increased; 60% of the samples reached a minimum penetration of 5 mm. Incubation time and conditions may need to be adjusted to achieve more consistent results. The results of this study show that biological incising can greatly improve the permeability of spruce and pine and can be achieved on 38 by 89 dimension lumber under conditions that could be utilized in an industrial setting. Future work should focus on determining incubation conditions that allow penetration requirements in Canadian standards to be met with acceptable strength loss.
A major constraint to the Canadian wood preservation industry in both domestic and export markets is the difficulty of penetrating Canadian wood species with preservatives. FPInnovations has put considerable effort into various forms of improved mechanical incising but these have not been adopted by the industry due to adverse effects on throughput and appearance of the final product. Recently, work in Europe has shown promising results from biological incising using white-rot fungi that colonize wood relatively rapidly but decay slowly. The use of European isolates of fungi in North America may be constrained by phytosanitary concerns. This report covers an experiment to screen North American isolates of white-rot fungi for potential as biological control agents. A modification of the soil-block test method was used to evaluate the ability of a range of fungi to improve permeability without affecting strength properties. Wood samples were exposed to the fungi for zero, two, four and six week time increments and were then treated with a 1.5% ACQ-D solution. Preservative uptake was calculated based on change in weight before and after treatment. Two isolates of Dichomitus squalens were found that dramatically increased preservative uptake. These samples were tested for strength loss and preservative penetration. Spruce samples exposed to D. squalens isolate 78A for six weeks were completely penetrated with preservative (19 mm depth) in all six samples. D. squalens 78B also showed promising results in pine and spruce samples based on uptake and penetration data. No stiffness loss was detected in any of these samples based on results from the crushing tests.
Ophiostomatoid fungi can pose serious risks to forest health, forest product value, and forest product exports. These fungi belong to at least two different orders, six teleomorph genera and ten anamorph genera, but share similar characteristics such as transmission by insect vectors and frequent association with tree hosts. Some produce bluestain in the wood causing losses in appearance grade markets, while others are more serious pathogens that can cause disease or kill their host trees and raise phytosanitary concerns in the global market place. In an effort to keep up with the rapidly advancing taxonomic changes and knowledge gains within these fungal groups, especially in regards to their associations with insect vectors, an INSECT-FUNGI database was created in 2005 to maintain literature on these fungi as well as to facilitate rapid data mining within the collected literature in order to explore feasible ways of detecting, monitoring and controlling these fungi. In addition, in 2008 an extensive literature review looked at the DNA-based tools used to identify and taxonomically place species within these groups. That work also reviewed the latest changes in the taxonomy of Ophiostomatoid fungi. In 2009, updates were made to the database as well as to the 2008 literature review. In addition, DNA-based identification decision making trees were created to give users tools to help identify mould and staining agents. The objectives of this report were to summarize the activities and updates in regards to the Insect-Fungi database, and to review the latest literature and news in regards to taxonomy, DNA-based identification, and other relevant information pertaining to Ophiostomatoid fungi. In addition we also included an update of a few non-ophiostomatoid fungi that cause bluestain, for example Diplodia and Lasiodiplodia.
Numerous new associations between insects, hosts and ophiostomatoid fungi have been discovered in the last three years. Thirty one new species of Ophiostoma were described in 2010 and several more are in the process of being described. There are currently four genera within Ophiostomatales; however, seven more are expected to be officially accepted in the near future. In addition to the ITS region of the ribosomal DNA, more research groups are routinely utilizing the ß-tubulin gene for describing new species and species complexes. A group at UBC completed sequencing the genome of Grosmannia clavigera and described mechanisms by which this fungus can detoxify host defence compounds, as well as use host terpenoids as a carbon source giving important insights into the relationships between fungus, beetle and tree.
The absence of commercial facilities to recycle or recover value from wood treated with metal-based wood preservatives at the end of its service life is one of the most significant negative points in the generally positive life cycle analysis of treated wood. An experiment was initiated to determine whether wood treated with carbon-based preservatives could be degraded by composting without residual preservative contamination. After one year the concentration of azoles remained high, while the concentration of DDAcarbonate was greatly reduced. Several fungal isolations were made from the compost mixtures. More time is needed to complete the composting process.
Comme l'ont démontré le développement et la mise en oeuvre des codes des méthodes de conception de troisième génération pour lutter contre les vibrations des planchers, FPInnovations joue un rôle important au Canada et à l'échelle internationale dans les comités de codes et de normes visant à protéger les consommateurs et l'industrie du bois et contribue à la croissance continue du marché de la construction en bois à l'échelle mondiale.
The widespread availability of genomics data and molecular tools for pathogen detection and identification provides scientists and regulators a powerful toolbox for pathogen monitoring. However, this raises questions and concerns regarding the use of these tools in import and export of forest commodities. Discussions around implementation and standardization have highlighted knowledge gaps around their efficacy and suitability in wood and their applicability to forest commodities. This study compared detection efficacy of various emerging tools on artificially infected forest and wood commodities, focusing on Phytophthora pathogens, an important group of invasive and sometimes difficult to detect species. In situ detection was more sensitive than traditional isolation, and for some methods, 100% of infected samples were positive. Detection efficacy varied by tissue type and detection method. The data generated from this study is important in addressing knowledge gaps around pathogen detection in wood.
Wood decay is one of the primary factors limiting wood as a building material, reducing the competitiveness of wood against other engineered products. Wood preservatives or other wood enhancing treatments can reduce the risk of decay; however, Canadian wood species such as spruce and pine are difficult to treat to meet Canadian and USA standards due to a thin sapwood band and refractory heartwood. This puts the Canadian wood preservation industry at a competitive disadvantage in both domestic and international markets. Biological incising with Dichomitus squalens was originally done in Austria in the 1990s to increase the permeability of European spruce prior to treatment with wood preservatives. In 2010, FPInnovations screened Canadian isolates of various white-rot fungi to identify an isolate that would be suitable for biological incising of Canadian spruce and pine. An isolate of Dichomitus squalens isolated from white spruce was found to greatly increase the permeability of the wood, particularly in spruce. Follow up studies in 2011 and 2012 confirmed that the results could be reproduced on commercial sized wood in non-sterile conditions, and showed that longer times would be required for bioincising in pine which is more resistant to D. squalens. Strength loss on small clear specimens with through treatment was slightly higher in some samples than with conventional incising. The solid inoculum method was very successful but would be difficult to commercialize. Laboratory tests showed that higher temperatures around 30 °C could be used to speed up growth, but still longer incubation times were needed for pine. The current study was undertaken to determine the effect and feasibility of three different inoculation methods on the bioincising process: inoculation with grain colonized by D. squalens, a liquid spray inoculation (via dipping and via spray), and a mycelial mat (mycelium grown on the surface of agar and grown on paper). In addition the higher incubation temperature on 2x4 samples of both pine and spruce was tested at four, five and six weeks incubation for spruce, and six, seven and eight weeks incubation for pine. Results from the experiment suggest that liquid inoculum (spray) performs as well as grain inoculum. Spruce samples exposed for six weeks reached an average penetration of 10 mm through the heartwood face and 22 mm through the edge. Forty percent of the samples reached a minimum of 10 mm penetration on the heartwood face, and 80% reached 10 mm penetration through the edge. The ease of application via spraying (liquid inoculation method) makes this a more desirable method to use in an industrial setting. The greatest increases in preservative penetration were at six weeks in the grain inoculated samples; however, five and six week’s incubation for liquid inoculation were close. The results for bioincising on pine were much more variable, and increasing the incubation time did not substantially increase preservative penetration. This suggests that the fungal isolate used may not be suited to pine wood.
The Canadian wood preservation industry is at a competitive disadvantage in both domestic and international markets because our major species (e.g. spruce and pine) are difficult to impregnate as they are characterized by a thin sapwood band and refractory heartwood which limits chemical penetration. Achieving adequate penetration may be even more challenging for the next generation of carbon-based and micronized preservatives. Biological incising with Dichomitus squalens, developed in Austria in the 1990s, increased permeability in European spruce. More recently, studies done on commercial sized pine and spruce with a Canadian isolate of D. squalens under non-sterile conditions showed through-treatment (19 mm penetration) with 1.7% ACQ after six weeks in spruce samples; however, strength loss was slightly higher in some samples than what is found with conventional incising. Penetration was more variable in pine. A shorter incubation time would be desirable in an industrial setting. The current study was undertaken in order to determine if the processing time could be shortened by optimizing incubation temperature. Three temperatures were tested on small pine blocks using a soil block test method. Samples were exposed for between two and six weeks. ACQ-D treatment was used in this experiment as a surrogate for carbon-based preservatives because copper is easier to detect than colourless carbon-based preservatives. Optimal temperature for incubation appeared to cover a wide range around 30 °C and no growth inhibition was encountered at 35 °C suggesting that temperature variability in an industrial setting should not inhibit a biological incising operation. Uptake and penetration was variable. After 5 weeks seventy percent of pine samples reached a minimum of 5 mm penetration, and 50 % of the samples reached a minimum of 10 mm penetration. Optimal incubation time still appears to be over six weeks in pine to reach minimum 10mm penetration requirements in over 80% of samples.
The goal of FPInnovations’ Wood Protection program is to assist industry deliver clean wood products to both export and domestic markets. Microorganisms (bacteria, mold, stain, decay, nematodes) can cause appearance problems, affect uptake of finishes, create phytosanitary and health concerns, and be involved in detoxification of wood preservatives. Users and consumers of wood often have questions about discolored wood.
Correct and rapid identification of factors causing wood discolouration is important in order to recognize appropriate mitigation options or control measures, to maintain market access for Canadian wood products, and assist in mediating disputes. This has led to a growing need for a structured approach for examination of wood discolouration and biodeterioration problems so that scientists involved have common approach and easily share the information during the assessment process. By taking advantage of recently acquired capabilities, in particular molecular biology methods, and in combination with existing knowledge and expertise, we developed an expert system (diagnostic tree) for rapid detection, identification and problem solving.
Four decision tree charts were developed to simplify the process of identifying the cause of wood discolorations. These steps are based on updated information, our booklet “Wood Discolorations and Their Prevention with Emphasis on Bluestain” and on our review of molecular–based technologies to aid identification and detection of ophiostomatoid (bluestain) fungi. The latter document has also been updated in this report. These charts are useful tools but cannot be a substitute for an expert assessment of discoloration issues, which sometimes may be complex in nature and may require a combination of structured methodology and a wealth of expert knowledge to assess.
The long-term performance of carbon-based preservatives is anticipated to be limited by detoxification through the action of microorganisms. This study identified primary colonizers of wood treated with carbon-based preservatives that may contribute to detoxification of the active ingredients. Wood coupons treated with three different carbon-based preservatives were subjected to a repeated wetting and drying cycle in an accelerated field simulator. Samples were harvested at different times: two, four, and eight weeks (16 and 32 week samples remain to be sampled). Samples were analysed by HPLC to determine the amount of chemical remaining at the surface of the sample. Chemical concentrations in the samples remained above reported toxic thresholds, and no depletion was seen between two and eight weeks. Wood slivers were chiselled from beneath the surface of the wood and plated. Isolates were identified by sequencing ribosomal DNA. Samples were dominated by bacteria that appeared morphologically similar between samples. DNA sequencing identified these isolates as a Pseudomonas species. Only three fungal isolates were found, one a Trichoderma sp., and the others are yet to be identified. Isolations and identifications will continue.