Phellinus sulphurascens Pilat (syn. P. weirii), the cause of Laminated root disease (DRL), occurs across a variety of biogeoclimatic ecological classification (BEC) zones in the southern interior of British Columbia (BC) (Lim et al. 2005). The disease causes mortality and growth loss in natural and planted stands of Douglas-fir (Thies and Sturrock 1995) and other conifers are also susceptible to infection by the fungus. DRL-caused mortality usually begins on infested sites five to seven years after stand establishment and may continue throughout a rotation. Chronic (non-lethal) infections on roots of older trees can result in growth loss. Some research has been conducted in coastal BC, Oregon and Washington to determine the distribution and impact of P. sulphurascens in second-growth stands of Douglas-fir. The disease has been estimated to occur in more than 80% of such stands in the Vancouver Forest Region of BC (Paul Wood as cited in Bloomberg and Reynolds 1985) and substantial reductions in timber volume and growth have been demonstrated in several stands on Vancouver Island (Bloomberg and Wallis 1979, Bloomberg and Reynolds 1985). The disease is estimated to occur on eight percent of the commercial forest land base in Washington and Oregon and cause a 40 to 70 percent reduction in wood volume on affected areas (Goheen and Hansen 1993).
Much less is known about the distribution and impact of DRL in BC?s southern interior, due in some part to research being focused on Armillaria root disease (DRA), another serious pest occurring in many BEC zones in southern BC. Phellinus sulphurascens is known to occur in the IDF, ICH, MS and SBS biogeoclimatic zones of the southern interior and its distribution appears to be quite patchy, with patch sizes ranging from 1 ha to more than 10 ha. Phellinus root disease often occurs in stands together with Armillaria root disease (DRA) caused by the fungus, Armillaria ostoyae and Douglas-fir bark beetle (Dendroctonus pseudotsugae). Just how these disturbance agents interact and influence individual tree and stand susceptibility to fungal infection and/or insect attack is not well understood.
In general, the presence of pathogens in BC?s forests and their impact on productivity are greatly underestimated. This is perhaps especially true for root disease and decay pathogens. For example, the 2005 Summary of Forest Health Conditions in BC (BC MFR 2006) report lists only four diseases (none of them root diseases) as causing any damage that was detectable from aerial overview surveys. Although the report acknowledges that ?some forest health concerns, particularly diseases?, are not usually discernable? from such overview surveys, it does not state where to find damage information for diseases. One of the end results of this situation is that there is little quantitative information on root disease incidence in the province. In a survey of client needs conducted by a Research Partnership in the province (Gregory and Satterfield 1999), more information about root disease, as it pertains to timber harvesting and management, was identified as a priority by a number of Partnership clients including licensees, provincial operations/policy, private consultants and other research groups. Finally, recent communications with Forest Health District staff and with foresters working in Industry reveal that DRL and the paucity of information about its incidence and impact are of significant concern to them. Thus, the goal of this project is to begin the research needed to accurately determine the incidence and impact of DRL in the southern interior of BC. This will require a step wise research approach that starts from a landscape level view of DRL occurrence and/or incidence and moves to a stand level view of DRL incidence and impacts.
Phellinus root disease poses a long-term threat to the productivity of managed stands in BC?s southern interior. This is partly beca ...
Cleary, Michelle R., Sturrock, Rona N.; Thorne, Susan. 2010. Distribution and impacts of Phellinus root disease in the southern interior of British Columbia. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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