Western white pine (pinus monticola) was the dominate species in forests within the inland northwest of washington, idaho, and montana

The Department of Agriculture Forest Service R1-Northern Region awarded Colorado State University $130,000 on July 1, 2026, under the Forest Health Protection program (CFDA 10.680) to develop management recommendations for rust-resistant western white pine plantations in the Inland Northwest.

The project addresses the decline of western white pine across Idaho, Washington, and Montana caused by white pine blister rust (an invasive pathogen introduced in the early 1900s), mountain pine beetle, harvesting, and fire exclusion. Since rust resistance breeding began in the 1960s and resistant seedlings were planted starting in the 1970s, higher-than-expected rust incidence and mortality have occurred, particularly in high-hazard-risk sites. Colorado State University will develop site-condition-based hazard rating stands for blister rust to guide future plantings of rust-resistant western white pine and inform restoration of this ecologically and economically significant species. Approximately 90 percent of native western white pine has been lost across the region since blister rust introduction.

Performance occurs in Idaho with a period of performance from July 1, 2026, through March 31, 2031.

However, the population of white pine has decreased significantly since the early 1900, and these decreases were caused by harvesting, fire exclusion, and mortality caused by mountain pine beetle and white pine blister rust (cronartium ribicola - c. Ribicola). C. Ribicola is an invasive, non-native pathogen that was introduced to the pacific northwest in the 1900S and white pines are highly susceptible. As a result, the species compositions of the northern idaho moist forest types have changed dramatically. The douglas-fir (pseudotsuga menziesii) cover type is almost double historic levels and the grand fir (abies grandis) / western hemlock (tsuga heterophylla) type has increased by five times. These tree species, which occur in greater portions because of the loss of white pines, are more susceptible to root diseases. Larger losses due to increased root disease has a large impact on timber production and recreation activities. Fortunately, there is resistance to white pine blister rust in populations of white pine, albeit in low numbers. Breeding efforts have been underway since the 1960S in northern idaho rust seedlings were planted in the inland northwest in the 1970S. Rust incidence and mortality within these planting were higher than expected, especially in sites with high hazard risk. This led to a monitoring project aimed at developing rating stands for blister rust hazard based on site conditions for white pine plantations. This project is needed to solidify management recommendations for future plantings of rust resistant western white pine. About 90 percent of the native western white pine were lost across the inland northwest since the introduction of the non-native white pine blister rust. These recommendations will guide restoration of this ecologically and economically important tree species.