Bluestain fungi reduce the market value of Canadian wood products causing significant economic losses and are considered by many countries as potential alien pests. One of the key knowledge gaps in bluestain biology is the source of the stain and how the bluestain fungi spread. This report is a compilation of reports that are included in the appendices (1-14), each with its own targeted objectives, methodologies, staff, and results and discussions. The acquired knowledge will help us design economical, effective and environmentally acceptable methods to control bluestain at different stages of the wood processing chain. In order to fill the knowledge gaps and identify new ones, we set up a worldwide collaboration where partners contributed much of the expertise, especially on fungal and insect identification. Forintek staff organise the industrial interface, do field work, isolate and identify fungi (in collaboration with partners), provide summary reports (updates) to members, and continue to maintain core competency in this field.
Stain inoculum is found associated with wood substrates, needles, cones and bark of trees (Appendix 4). Harvester heads presumably pick up stain inoculum while touching wood, soil and woody debris. During harvesting they push the inoculum together with pieces of bark and other debris deeper in sapwood, clearly playing a role in direct dissemination. Harvesters also puncture the wood and loosen and remove bark, which provides access to sound wood for a plethora of organisms. If mechanically harvested logs are left unattended for several weeks under warm and humid conditions they can develop bluestain solely based on the stain inoculated during harvesting. Stain control methods therefore need to be applied immediately. This can include hot logging (log delivery and processing within 2-4 weeks), water storage, debarking, drying and antisapstain treatments (including biocontrol).
Numerous insects visit standing trees and logs in storage. Insects are known to be one of the major vectors for bluestain fungi. Despite a great deal of research on insect-fungi relationships, there remain many unanswered questions. These include the specificity and the importance of these associations for both partners, and pathogenic potential and staining ability of associated fungi. Very few beetles can attack healthy standing trees, like the Mountain pine beetle, which causes bluestain that cannot be prevented unless the beetle is controlled. Some insects, especially bark and ambrosia beetles, may attack only one type of host and carry only one or two specific fungi. Others can attack many hosts and can carry a variety of fungi. Some of these associations are very specific and the survival of an insect depends on the fungus. In other systems the fungus may be a weed picked up casually. We created an insect-fungi database to conveniently capture and update information on known insect-fungi associations currently focusing on bark and ambrosia beetles. Often the primary beetles carry more pathogenic symbionts and are more extensively studied than in secondary, later-arriving, beetles where little information exists on their fungal associates. New associations are regularly being discovered. Novel approaches in stain and disease control aim to trap insects that carry fungi of significance using semiochemicals (“message-bearing” biochemicals). The database will be used as an aid to manage and access the critical information that might lead to novel methods of control. To date, 200 articles have been entered (Appendices 1, 2, 3, 5, 6, 10, 11, and 12).
The insect-fungus database is complementary to the Ophiostomatoid fungi database that has been developed at UBC through partnerships with Forintek and scientists around the world. The first phase is realized and this online database now contains all the available information on the most economically important species of sapstain fungi. It includes fungi-host-vector-geographical location relationships; both published historical information and new information acquired through fieldwork. With the help of our partners it will be continuously improved and updated during its lifetime (Appendices 7, 8, and 9).
We also studied other potential stain sources. In early February 2004 the Forintek team went to two BC mills that process bluestained, mountain-pine-beetle-attacked logs and sampled air and airborne sawdust at six locations in the mills, as well as from sawmill machines and surrounding snow. Stain fungi were rarely found in the air, accounting for up to 0.4 % of the total amount of fungal propagules in the dustiest areas of the mills. Live stain fungi were found in the snow (1-2 % of total cultured organisms), but the largest counts of stain fungi were found near machines with the dust settling method, and directly on the mill machines (up to 20.5% of total cultured organisms). This suggests that machinery may play the most significant role in stain inoculation to clean wood, while large sawdust pieces may play a significant role only for short distances (Appendix 13).
With increased emphasis in the Canadian forest products industry on extracting the most value from logs, this work will continue under ongoing project Biology and Management of Bluestain Fungi. It will continue to address the problem in order to recognise situations and ways where stain may be prevented along the wood processing chain (Appendix 14).