Caring for the Land and Serving People
White pine blister rust (WPBR) is a lethal, nonnative disease of white (5-needled) pines. It was introduced to North America from Asia, via Europe, in the early 20th century. Since then it has slowly spread through the continent in areas where white pines grow. Because the nine susceptible species of white pines native to North America have not evolved with the pathogen, many of them have little or no genetic resistance and soon die from the disease. The disease has caused extensive and permanent changes to ecosystems in many areas, greatly affecting ecosystem, wildlife and timber values in many cases.
A poster is available to provide information to the public on white pine blister rust. You can download and print the PDF file.
A 3-fold, two-sided flier with the same information is also available. It is also a PDF file.
White pine blister rust was found in northern Colorado, near Redfeather Lakes, in 1998 (Johnson and Jacobi 2000). Incidence of infected limber pine ranged from 3 to 50% of trees. Cankers appeared to be 3 to 5 years old; no tree mortality due to the rust was observed. The highest incidence of blister rust was near the Colorado and Wyoming state line. The disease appeared to have spread from nearby known infections in southern Wyoming.
Subsequent surveys in Colorado resulted in the discovery, in September 2003, of the disease in the Wet Mountains (Custer County) and Sangre de Cristo Mountains (Huerfano and Alamosa counties). In the Wet Mountains on the San Isabel National Forest (NF), the disease was found in several locations along State Highway 165 between Bigelow Divide and Lake Isabel, with the greatest intensity near the San Isabel Scout Camp. In the Sangre de Cristo Mountains, the disease was found on Mosca Pass and on both the east side (San Isabel N.F.) and west side (Great Sand Dunes National Monument and Preserve) of the Pass. It was also found on Madeno Pass. Because the disease appears to have been in the area for 10-20 years, it is likely on the Rio Grande National Forest also.
Although most of the new finds are in limber pine, the first record of the disease in nature on either bristlecone pines (Pinus aristata or P. longaeva) was obtained near Mosca Pass on P. aristata, Rocky Mountain bristlecone pine. Most of the range of P. aristata is in Colorado, and the disease is now among some of the largest stands of this species. Rocky Mountain bristlecone pines up to 2,435 years old have been found in Colorado. Southwestern white pine is also a potential host in southern Colorado.
Additional new finds were made in northern Colorado in 2005/2006. A map of the known distribution of the disease in the Rocky Mountain Region, current as of March 2007, can be downloaded (1.2 MB PDF).
White pine blister rust has devastated some forests and has the potential to do the same in Colorado. High rates of mortality may be expected over time. This may affect treelines, the fire regime in subalpine forests, wildlife that feed on white pine seed, and other aspects of ecosystem structure and function. Unlike impacts of native diseases and insects, the effects are likely to be permanent, unless, with our assistance, genetic resistance in white pine populations is found and reproduction of resistant trees is facilitated.
The nearest known infestations of WPBR are on the Wyoming border to the north and the Gallinas Mountains of central New Mexico. This is a very long distance for such a pathogen to disperse. It is not known how the fungus was carried so far, nor from where, but two means of dispersal are suspected. One is the dispersal of spores in high-altitude winds from distant infestations, which may be a rare, but significant, event. Another is dispersal by humans transplanting infected white pines.
Options for managing the disease are limited. Surveys will continue in Colorado to delimit infested areas and find any new infestations. Colorado State University is working on a hazard rating system for Colorado. US Forest Service researchers are developing management options to help sustain and restore bristlecone and limber pine ecosystems in the presence of the disease. Ultimately, programs to find and develop disease resistance in our native white pines may also be an important means of long-range restoration of damaged ecosystems.
Because the disease can be moved to new areas on infected plants, one important step that homeowners and nursery operators can take is to minimize transplanting of white pines and to do no transplanting from infested areas. Because symptoms of the disease may not be evident for several years after infection, white pines should never be removed from forests known to be infested. If white pines must be used in landscaping, nursery operators and their customers should insist on documentation of the geographic origin of transplanted white pines, and none should be accepted from infested areas.
Contacts: Kelly Burns, Lakewood Service Center (northern Colorado), and Jim Worrall, Gunnison Service Center (southern Colorado).Johnson, D.W. and Jacobi, W.R. 2000. First report of white pine blister rust in Colorado. Plant Disease 84(5): 595.
White pine blister rust has been found in a stand of limber pine (Pinus flexilis) in Custer State Park of South Dakota. Although limber pine is not a marketable tree, it is an important species for forest biodiversity management in the Black Hills of South Dakota. The disease was first reported in South Dakota (Lundquist et al. 1992) at Custer State Park in the Cathedral Spires Trail area (T2S, R5E, sec. 28). This site was surveyed for white pine blister rust in 1996 and permanent plots installed in 1997 for long term monitoring of the disease. Low incidence of white pine blister rust disease still occurs in Custer State Park with only 25% of the examined trees infected. However, eight of these trees contained lethal stem cankers so the disease is causing some mortality in the area. Contact: Jim Blodgett, Rapid City Service Center.
Lundquist, J.E.; Geils, B.W.; and Johnson, D.W. 1992. First report of white pine blister rust on limber pine in South Dakota. Plant Dis. 76:538.
White pine blister rust occurs at varying infection levels in several whitebark and limber pine stands in Wyoming. Whitebark pine (Pinus albicaulis) has been described as a "keystone" species and is used by several animal species as a food source (Kendall and Hoff 1995). Limber pine often occupies harsh sites where no other tree species can grow in the Rocky Mountains (Kendall and Schirokauer 1997). Region 2 Forest Health Management installed 22 permanent plots for long term monitoring of this disease in the Bighorn, Medicine Bow, Shoshone National Forests and Yellowstone National Park. Most areas had low incidences of the disease, but a few locations had moderate to high levels of infection. White pine blister rust is contributing to decline of white pines in the Rocky Mountains (Kendall et al. 1996, Smith and Hoffman 1998, Taylor and Schwandt 1998). Forest Health Management will continue to monitor these permanent plots for changes in the incidence and severity of the rust on these sites. Contact: Jim Blodgett, Rapid City Service Center.
Kendall, K.C. and Hoff, R.J. 1995. An introduction to whitebark pine ecology and status. Proc. of the 43rd annual Western International Forest Disease Work Conference; comp. Mathiasen, R.L.; Whitefish, MT; Aug. 29 Sept. 1, 1995. p.97-102.
Kendall, K.C. and Schirokauer, D. 1997. Landscape assessment of the decline of whitebark pine (Pinus albicaulis) in the Bob Marshall Wilderness Complex. Montana, USA. Northwest Science 68 (3) 213-229.
Kendall, K.; Schirokauer, D.; Shanahan, E.; Watt, R.; Reinhart, D.; Cain, S.; and Green, G. 1996. Whitebark pine health in Northern Rockies National Park Ecosystems; a preliminary report. Nutcracker Notes, USDA Forest Service Intermountain Research Station; Missoula, MT, Dec. 22, 1996. Number 7: 16-23.
Smith, J. and Hoffman, J. 1998. Status of white pine blister rust in Intermountain Region white pines. USDA Forest Service, Intermountain Region, Report No. R4-98-02.
Taylor, J.E. and Schwandt, J.W. 1998. Dothistroma needle blight on limber pine in Montana. USDA Forest Service, Northern Region, Rep. 98-4.
Caring for the Land and Serving People