Laminated Root Disease - Stand Establishment Decision Aid

Laminated (or Phellinus) root disease (Phellinus sulphurascens Pilat, syn. = P. weirii) is a major, naturally occurring disturbance agent in interior forests and poses a significant threat to its most economically important host, Douglas-fir. The disease spreads below ground at root contacts. In the southern interior of British Columbia, P. sulphurascens often occurs together with Armillaria root disease (Armillaria ostoyae) and (or) Douglas-fir bark beetle (Dendroctonus pseudotsugae). Stand volume in infested areas can be significantly reduced through growth loss and decay, mortality, and windthrow. Post-harvest retention of infected stumps in the soil increases inoculum potential on affected sites, which poses a risk of infection to regenerating trees. Mitigation of disease impacts can best be achieved by recognition of the disease and incidence assessment prior to harvest, and by modification of harvesting and silviculture practices that will minimize exposure of trees to inoculum. The Stand Establishment Decision Aid (SEDA) format has been used to extend information on various vegetation and forest health concerns in British Columbia. This decision aid summarizes information about laminated root disease occurrence and management in the Southern Interior Forest Region. The first sections provide general information, hazard ratings, and biological and silvicultural considerations for Phellinus root disease. The article then outlines growth and yield implications, other effects and associations of the disease, and various techniques to manage the disease. It also includes a list of references and resources to provide readers with more detailed information. Reference material that is not available online can be ordered through libraries or the Queen’s Printer at http://www.qp.gov.bc.ca.