2007 Blister Rust Screening of Plus Trees from the GYGT Seed Zone

Project: Blister Rust screening of selected plus trees from Greater Yellowstone-Grand Teton seed zone

Agency/Forest or Park/District: Coeur d’Alene Nursery

Project coordinator:   Mary Frances Mahalovich

Contact:   Mary Frances Mahalovich, Regional Geneticist

USDA Forest Service, Northern, Rocky Mountain, Southwestern and Intermountain Regions, FSL 1221 S. Main St., Moscow, ID 83843.  208-883-2350  mmahalovich@fs.fed.us


USDA Forest Service Northern, Rocky Mountain and Intermountain Regions, Grand Teton NP, Yellowstone NP, Coeur d’Alene Nursery, Forest Health Protection, Greater Yellowstone Coordinating Committee, Whitebark Pine Subcommittee.

Source of funding /amount

FHP: $55,000

Supplemental funding: $55,000. Forests, Parks, GYCC and WBEF contributed funds to collect plus tree seeds. NFS (Forest & Rangeland and Wildlife Staffs) provided funding for 110-seed source study, which provides baseline for comparison and successful protocols to extend a rust screening to this broader sample (seed from n=113 plus trees).

Dates of restoration efforts

The seeds were sown at CDA nursery in December 2007, inoculated with blister rust September 2010, data collected for rust symptoms, survival and early height growth during four inspection periods (June 2011, September 2011, September 2012, and September 2013) (Figure 1).


Determine rust resistance, survival and height growth among open-pollinated progeny of 113 plus trees. Rank plus trees based on the performance of their progeny and identify promising cone collection areas based on proven rust resistance. Select elite trees for scion and pollen donors for seed orchard development.

Acres/ha treated

Greater Yellowstone-Grand Teton seed zone (2.5 million acres of whitebark pine in the 24-million acre Greater Yellowstone Ecosystem).

Mahalovich_2007_Pic1_by D. Foushee, CDA Nursery

Picture 1.  Cycle 1 whitebark pine blister rust screening trial of the Central Montana and Greater Yellowstone-Grand Teton seed zones, Coeur d’Alene Nursery, 2007-2013.


Sow and grow individual seed lots, artificially inoculate container seedlings with blister rust at the end of the third growing season, transplant container seedlings to nursery beds and collect survival, rust, damage and height data using established protocols for whitebark and western white pine.

Planting? If so, source of seedlings? Resistance?

No. Experiment: seeds from local resistant trees.


The rust screening at Coeur d’Alene Nursery involves the direct assessment or derivation of seven, blister rust resistance traits.  Utilizing four of the traits that can be directly assessed on individual seedlings, the overall percent rust resistance is 9% based on a heavy spore load of 28,098 basidiospores per cm2.  Rust resistance among the 113 selections ranges from 0 to 64%.  The most rust-resistant plus tree is 6863 at Apex Trail in Grand Teton National Park and the most rust-susceptible plus tree is 6649 at Sawtell Peak on the Caribou-Targhee NF.  Six plus trees exhibited no blister rust resistance, as measured by percent rust resistance or by an index among spots per m2, early stem symptoms, bark reaction and canker tolerance.  The heavy inoculation provides the baseline or lowest anticipated level of rust resistance among these GYGT selections.  The 110-seed source study with 25 GYGT plus trees provided the upper bounds of 28% blister rust resistance using a much lighter spore load of 3,695 basidiospores per cm2 (Mahalovich et al. 2006).  Realized percent rust resistance of whitebark pine in the GYGT is likely somewhere between 9-28% (Figure 2).

Heritability, expressed as a ratio of the additive genetic variation or that portion of the genetic variation that can be passed on to the next generation, divided by the total phenotypic variation, ranges from a value of 0 to 1.  The family heritability for rust resistance in the GYGT is 0.72 indicating whitebark pine has a moderate level of rust resistance that can also favorably respond to selection and breeding.  Current rust-resistance levels from artificial inoculation trials guide silvicultural prescriptions to determine appropriate stocking levels (trees per acre) to achieve a desired future condition.


Mahalovich_2007_Pic2_ by M. F. Mahalovich, USFS Northern Region

Picture 2.  Blister rust resistance levels in Northern Rockies whitebark pine.


The blister rust resistance level for the Greater Yellowstone Ecosystem was determined from a broad geographic sample of plus trees among several agency partners.  Elite tree selections have been made and the Little Bear seed orchard design has been changed to reflect rust resistance rankings.  Scion collections for seed orchard grafting with these newer findings began fall 2013.  Pollen collections will begin early summer 2014.  An operational cone collection list of proven blister rust resistant seed sources in the top 25th percentile have been provided to GYCC collaborators.  This list will guide cone collection efforts for restoration planting until the seed orchard (Figure 3) reaches reproductive maturity.

Monitoring since completion of the project

Through collaborative efforts of the Greater Yellowstone Coordinating Committee’s Whitebark Pine Restoration Strategy (2011), survivors of the blister rust screening will be planted in a long-term performance test at Little Bear (Gallatin National Forest) to monitor the long-term durability of blister rust resistance, the stability of individual, rust-resistant traits, and effective population size or family representation over time.


July 2014 (or first access to the site).

Plans for future monitoring?

Subsequent field measurements in the Little Bear Cycle 1 performance test are identified in the table below:

Unit Whitebark Pine           Test to be Measured Cyc 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023
  GALL Seed Zone GYGT 1 1yr 3yr 5yr 7yr 10yr

Will outcome meet goals?

The completion of the blister rust screening is fully successful and exceeded all expectations of an operational, rust screening of 200 plus trees (the CLMT seed zone was also tested concurrently) and two controls.  Experience gained in sowing and growing of this species have refined protocols, trimming off one year of the rust screening cycle (now inoculate a 2-year rather than 3-year container seedling) at Coeur d’Alene Nursery.

Picture 3.  W pine Little Bear Seed Orchard, Gallatin National Forest, September 2013 (left to right Keith Konen and Clay DeMasters)

Picture 3. W pine Little Bear Seed Orchard, Gallatin National Forest, September 2013 (left to right Keith Konen and Clay DeMasters)

Future actions/follow up?

Additional GYGT plus trees are being evaluated in the Cycle 4 (inoculated September 2013) and Cycle 5 rust screenings.  Other Northern Rockies and Nevada seed zones are being evaluated in Cycles 2-5.  Plant materials from the Cycle 1 GYGT rust screening are being utilized to evaluate other key adaptive traits and their correlated response with blister rust resistance in the context of more recent climate change models.  Plus tree seed from the GYGT seed zone has also been used to characterize three molecular markers in whitebark pine (isozymes, mtDNA and cpDNA) (Mahalovich and Hipkins 2011), identify genetically diverse locations for in situ conservation, while building sufficient seed stores for ex situ gene conservation.

Miscellaneous comments

Data collected on individual plus trees throughout the GYGT seed zone, and 100-tree blister rust, canker count, and mountain pine beetle surveys among 76 unique populations in the Greater Yellowstone Ecosystem contributed to the Interagency Grizzly Bear Study Team’s “Grizzly Bear Food Synthesis Team Report” http://nrmsc.usgs.gov/research/igbst/GBFSR_Refs and white paper on the future status of whitebark pine (Mahalovich 2013) available at the following link http://www.fs.usda.gov/detail/r1/plants-animals/?cid=stelprdb5341541 .

Greater Yellowstone Coordinating Committee Whitebark Pine Subcommittee (GYCCWBPS). 2011. Whitebark Pine Strategy for the Greater Yellowstone Area, 41 pp.
Interagency Grizzly Bear Study Team.  2013.  Response of Yellowstone grizzly bears to changes in food resources:  a synthesis.  Report to the Interagency Grizzly Bear Committee and Yellowstone Ecosystem Subcommittee.  Interagency Grizzly Bear Study Team, U.S. Geological Survey, Northern Rocky Mountain Science Center, Bozeman, Montana, USA, 58 p. http://nrmsc.usgs.gov/research/igbst/GBFSR_Refs
Keane, R.E., Tomback, D.F., Aubry, C.A., Bower, A.D., Campbell, E.M., Cripps, C.L., Jenkins, M.B., Mahalovich, M.F., Manning, M., McKinney, S.T., Murray, M.P., Perkins, D.L., Reinhart, D.P., Ryan, C., Schoettle, A.W., Smith, C.M., 2012.  A range-wide strategy for whitebark pine (Pinus albicaulis). USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO, General Technical Report RMRS-GTR-279, 108 pp.
Mahalovich M.F., Dickerson, G.A., 2004.  Whitebark pine genetic restoration program for the Intermountain West (United States).  Proc. IUFRO Working Party 2.02.15 Breeding and genetic resources of five-needle pines:  growth, adaptability and pest resistance, 23-27, July 2001, Medford, OR, USA.  USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO, USA, Proceedings RMRS-P-32, pp. 181-187.
Mahalovich, M.F., Burr, K.E., Foushee, D.L., 2006. Whitebark pine germination, rust resistance and cold hardiness among seed sources in the Inland Northwest:  Planting Strategies for Restoration.  In: National Proceedings:  Forest and Conservation Nursery Association; 2005 July 18-20; Park City, UT, USA.  Proc. RMRS-P-43.  Fort Collins, CO:  US Department of Agriculture, Forest Service, Rocky Mountain Research Station, pp. 91-101.
Mahalovich, M.F., Hipkins, V.D., 2011.  Molecular genetic variation in whitebark pine (Pinus albicaulis Engelm.) in the Inland West.  In: Keane, R.E., Tomback, D.F., Murray, M.P., Smith, C.M. [Eds.]  The future of high-elevation, five-needle white pines in Western North America: Proceedings of the High Five Symposium; 28-30 June 2010; Missoula, MT. Proceedings RMRS-P-63, USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO, USA, pp. 124-139.
Mahalovich, M.F., 2012. Lessons Learned from the Inland West Whitebark Pine Genetics Restoration Program.  Nutcracker Notes 22, 13-14.
Mahalovich, M. F.  2013.  Grizzly bears and whitebark pine in the Greater Yellowstone Ecosystem.  Future status of whitebark pine: blister rust resistance, mountain pine beetle, and climate change.  U.S. Department of Agriculture Forest Service, Renewable Resource Management Northern Region White Paper, 2470 RRM-NR-WP-13-01, 59 p. http://www.fs.usda.gov/detail/r1/plants-animals/?cid=stelprdb5341541 .