OREGON – USDA Forest Service scientists have found promising genetic resistance for whitebark pine against white pine blister rust disease. In partnership with the National Park Service and various American Indian Tribes, the Forest Service identified parent trees in several populations of whitebark pine with natural resistance to the pathogen.  Researchers are utilizing these resistant trees for restoration and recovery of whitebark pine.

In January 2023, whitebark pine was listed as threatened under the Endangered Species Act, providing added urgency for the agency to finish preparing and implementing a national restoration plan.  A key factor in the elevated ESA listing is the impact of a non-native white pine blister rust disease to the species. 

A new publication, Disease resistance in whitebark pine and potential for restoration of a threatened species, is likely the most detailed account of white pine blister rust resistance to date (perhaps in any forest tree species). The paper, which was first released in October 2023, provides details of the frequency, level, and geographic distribution of disease resistance within this threatened species, and how it can be used in restoration efforts.

The publication’s findings are based on white pine blister rust inoculation trials in seedling families of 225 whitebark pine parent trees at Dorena Genetic Resource Center. In these trials, 215 of the parent trees were selected from various locations across Oregon and Washington, including twelve National Forests, two National Parks, and lands of the Confederated Tribes of Warm Springs.

Scientists found wide variation among seedling families in genetic resistance, ranging from highly susceptible to moderately resistant. Seedlings from more than 1,500 parent trees were then evaluated with many showing resistance to the disease. These results provide cautious optimism about the potential for future recovery of this keystone tree species.
In the Pacific Northwest Region, the Forest Service has already begun restoration plantings, using seedlings grown from the parent trees with the highest resistance to the rust.

Visit the USDA Forest Service Pacific Northwest Regional website for additional information about whitebark pine blister rust research.