Disease Screening for Endangered Whitebark Pine Ecosystem Recovery

Whitebark pine (Pinus albicaulis) is a high-mountain keystone and foundation species that is declining throughout most of its range in Western Canada. An introduced pathogen (Cronartium ribicola) causing white pine blister rust has led to the tree being listed as a federal species at risk. A disease screening program relies on carefully selecting potentially resistant parent trees, followed by testing their respective progenies. Beginning in 2011, trees were selected for controlled inoculations and field trials of seedling families. The performance of each seedling family indicates the level of disease susceptibility, implying genetic resistance in the parents. To date, we are screening hundreds of wild-collected parents. Based on post-inoculation assessments, almost one-third of our carefully selected parents have produced seedlings showing low susceptibility to disease. Numerous stakeholders are now beginning to plant disease resistant seedlings while also supporting the establishment of seed orchards and clone banks. Due to everchanging pathosystems, long-term diseasem screening will remain a critical contribution to the recovery of this valuable species.