Bluestain, caused by fungi, is an important and costly problem for the Canadian forest products industry. Conifers, such as pines, are especially susceptible to bluestain infection and development in logs. This prevents the recovery of appearance-grade wood products from those logs. The original objective of this project was to determine what fungi cause the greatest problems in a specific sawmill yard and to determine the mechanism of dispersion of these fungi. The selected sawmill is typical of northern Alberta or BC practice where the logging is done almost entirely in winter. Sufficient logs are brought in to the mill yard to cover the year's sawmilling. However during the summer the logs become stained. We originally surmised that the logs would be virtually free of stain when cut in the winter months. Based on literature we had assumed the vector of the staining fungi would be an insect. The spores of staining fungi are normally not airborne but are sticky and adhere to insects or other arthropods that carry the spores on their bodies. An insect control program might thus be devised to stop the insects and thereby reduce stain.
Shortly after starting the project we realised that the problem was more complex than it first appeared. We could not assume that the logs were largely free of infection when they reached the mill but needed to test that. We therefore extended the objective to determine the major sources of bluestain and the mechanisms of their dispersion in general in both logging sites and mill yards. This also required extending the length of the project.
In project planning several action items were identified. Progress has been made on some of these. During 2000 a number of essential contacts including universities, government and industry were established. Several have already contributed to the project. A literature review of the reported insect-fungi associations was done and is included in this report. Field trapping techniques for insects likely to carry stain were tested. By using a selection of commercially available lures, Lindgren funnel traps were shown to be capable of attracting a variety of target insects. To determine their fungal associates, these insects need to be immediately isolated and put in separate clean vials for later sampling. A larger scale field trapping will be done in subsequent years. Techniques for isolating fungi from insects were investigated and refined. This work demonstrated procedures which proved efficient and which will be used for larger scale work. Methods to investigate links between harvesting and fungal infection were also developed. A collaborative trial that is looking into dissemination of fungi by harvesters was set up with Forest Research (NZ) and Oregon State University. Preliminary work has tested the methods, which will be repeated on a larger scale in 2001.
The project is now considerably larger in scope than originally planned. It should determine the most significant ways of stain dissemination. The aim is to do this work as a set of collaborative experiments wherein as much of the expertise on insect and fungal identification and ecology as possible is contributed by our partners. Forintek will organize the industrial interface of the work.