Source: ROCKY MOUNTAIN RESEARCH STATION submitted to
UNDERSTAND HOW HOST-PATHOGEN INTERACTIONS AND ENVIRONMENTAL FACTORS INFLUENCE INVASIVE DISEASES, PRIMARILY WHITE PINE BLISTER RUST
Sponsoring Institution
Forest Service/USDA
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0197357
Grant No.
(N/A)
Project No.
RMRS-4155-3
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jun 20, 2006
Project End Date
Jun 20, 2011
Grant Year
(N/A)
Project Director
Ferguson, D. E.
Recipient Organization
ROCKY MOUNTAIN RESEARCH STATION
240 WEST PROSPECT ROAD
FORT COLLINS,CO 80526-2098
Performing Department
FORESTRY SCIENCES LAB - MOSCOW, ID
Non Technical Summary
Almost 100 years after its accidental introduction to western North America, the invasive white pine blister rust continues to decimate western white pine and whitebark pine. The rust disease cycle is from pines to an alternate host and then back to pines. Until 2004, gooseberries and currant bushes (Ribes species) were thought to be the only alternate host in the western U.S. The discovery of two new host species by scientists in RMRS-4552 and RMRS-4155 will change our recommendations for managing white pine blister rust. The purpose of this research is to provide new information and options for management and restoration of white pines.
Animal Health Component
(N/A)
Research Effort Categories
Basic
10%
Applied
90%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1230612108050%
2020612108030%
2160612108020%
Goals / Objectives
White pine blister rust fungus, a native of Eurasia, was inadvertently introduced to western North America in 1910. Since then, the abundance of the western white pine cover type has been reduced about 90 percent on 5 million acres in the northern Rocky Mountains, and the whitebark pine cover type is being similarly reduced on approximately 13 million acres in the western U.S. Both western white pine and whitebark pine are keystone species for ecosystem health and sustainability because they determine the ability of other species to persist in the community; so knowledge of host resistance and pathogen virulence in this pathosystem will provide needed options for management and restoration. For almost 100 years, blister rust was thought to have only one obligatory alternate host (Ribes species), but in 2004 researchers in RMRS-4552 and RMRS-4155 discovered two new alternate host genera Pedicularis and Castilleja. This discovery may help explain why Ribes eradication failed to stop the spread of the disease, but it also means that we need to look more closely at the host, pathogen, environment, and their interactions. Our objective is to understand how host-pathogen interactions and environmental factors influence invasive white pine blister rust in order to develop effective management strategies for western white pine and whitebark pine ecosystems and mitigation options for blister rust impacts.
Project Methods
Substantial gains have been made in breeding for resistance to blister rust in western white pine. Seed orchards are providing rust-resistant seed, and managers in the northern Rocky Mountains are planting rust-resistant seedlings. Whitebark pine has also shown genetic resistance to blister rust. This work unit is cooperating with the USFS Region One Tree Improvement Program to incorporate multiple-gene resistance into white pines. The host-pathogen interactions of white pine blister rust pathosystem are still very dynamic, almost 100 years after the disease reached western North America. The rust can adapt to specific environments and hosts. Appropriate management techniques can encourage a pathogen that will become less damaging over time; mismanagement can lead to protracted epidemics. The developing discipline of landscape genetics will examine structure of hosts, alternate hosts, and pathogens across the landscape. Linking geographic information system technology with host species distribution and hazard rating systems will allow management practices to be tailored to specific areas. The discovery of new alternate hosts for white pine blister rust will undoubtedly change our recommendations for managing white pine blister rust. A combination of molecular genetic and field studies will be used to determine how much the two newly discovered hosts contribute to infection rates, and how this information may be useful in developing management recommendations.

Progress 06/20/06 to 06/20/11

Outputs
OUTPUTS: This project is being terminated. The research will continue in RMRS Project 4157-1

Impacts
(N/A)

Publications


    Progress 10/01/06 to 09/30/07

    Outputs
    White pine blister rust is caused by the fungus Cronartium ribicola, which was inadvertently introduced to western North America in 1910. From 1923 to 1968, attempts were made to interrupt the disease cycle by eliminating Ribes bushes (the obligatory alternate host for blister rust). Ribes eradication did not work, and this effort was abandoned in 1968. Ongoing efforts since 1950 have been directed toward breeding genetically rust-resistant pines. Scientists in this RWU and RWU-4152 recently discovered two non-Ribes alternate hosts to blister rust -- Pedicularis (lousewort) and Castilleja (paintbrush). This RWU continues to investigate the ramifications of the discovery of two new alternate hosts (in cooperation with RWU-4152). The discovery of multiple North American alternate hosts suggests unrecognized complexity in blister rust's ability to exploit additional ecosystems southward into Arizona, New Mexico, and Mexico.

    Impacts
    We are currently in a paradigm shift as we discover the interactions among multiple alternate hosts and several white pine species in western North America. New scientific information will be used to design hazard rating systems that include Pedicularis and Castilleja, and recommend changes to genetic breeding programs that develop rust-resistant white pines.

    Publications

    • Richardson, B.; Zambino, P.; Klopfenstein, N,; McDonald, G.; Carris, L. 2007. Assessing host specialization among aecial and telial hosts of the white pine blister rust fungus, Cronartium ribicola. Canadian Journal of Botany. 85: 299-306.
    • Zambino, P.; Richardson, B.; McDonald, G.; Klopfenstien, N.; Kim, M.-S. 2006. A paradigm shift for white pine blister rust: Non-Ribes alternate hosts of Cronartium ribicola in North America. In: Guyon, J., comp. Proceedings of the 53rd Western International Forest Disease Work Conference; 2005 September 24-28: Jackson Hole, WY. 161-164.
    • Zambino, P.; Richardson, B.; McDonald, G. 2007. First report of the white pine blister rust fungus, Cronartium ribicola, on Pedicularis bracteosa. Plant Disease. 91: 467.
    • Richardson, B.; Warwell, M.; Kim, M-S.; Klopfenstein, N.; McDonald, G. 2007. Integration of population genetic structure and plant response to climate change: sustaining genetic resources through evaluation of projected threats. Proceedings: Advances in Threat Assessment and Their Application to Forest and Rangeland Management: 2006 July; Boulder, CO.
    • Kim, M.-S.; Klopfenstein, N.; Hanna, J.; Zambino, P.; Richardson, B. 2007. Application of phylogeographic analysis to predict sources of potentially invasive forest pathogens. Phytopathology. 97: S138.
    • Richardson, B.; Kim, M.-S.; Klopfenstein, N.; Zambino, P. 2007. Predicting potentially invasive pathogens by phylogenetic analyses of intercontinental relationships among plant hosts and pathogens. Phytopathology. 97: S138.


    Progress 10/01/05 to 09/30/06

    Outputs
    White pine blister rust, caused by the fungus Cronartium ribicola, was inadvertently introduced to western North America in 1910. Since then, it has reduced the western white pine cover type in the northern Rocky Mountains by about 90%, and similar reductions are occurring on whitebark pine. From 1923 to 1968, attempts were made to interrupt the disease cycle by eliminating Ribes bushes (the obligatory alternate host for blister rust). Ribes eradication did not work, and this effort was abandoned in 1968. Ongoing efforts since 1950 have been directed toward breeding genetically rust-resistant pines. Scientists at the Moscow, Idaho, laboratory have discovered two unknown host genera that contribute to the disease cycle. Pedicularis (lousewort) and Castilleja (paintbrush) are infected by blister rust, and the rust on these two genera infects white pines.

    Impacts
    This once-in-a-lifetime discovery will cause a major change in our thinking about how this host-pest system operates. It is not yet known how much these two genera contribute to the spread of the disease, but certainly stand hazard rating systems will have to be modified. Silvicultural systems may need to be designed that discourage Pedicularis and Castilleja. And we need to determine if the two new host genera are infected with the same race of blister rust as Ribes. If different races of the rust are involved, we may need to redesign the rust-resistance breeding program. There are six other white pine species in the western U.S. that may be similarly impacted.

    Publications

    • G.I. McDonald; B.A. Richardson, P.J. Zambino; N.B. Klopfenstein, and M.-X. Kim. 2006. Pedicularis and Castilleja are natural hosts of Cronartium ribicola in North America: a first report. For. Path. 36:73-82
    • P.J. Zambino; B.A. Richardson; G.I. McDonald; N.B. Klopfenstein; M.-X Kim. 2006. Non-Ribes Alternate Hosts of White Pine Blister Rust: What this Discovery Means for Whitebark Pine. Nutcracker Notes, Whitebark Pine Ecosystem Foundation 10:6-7


    Progress 10/01/04 to 09/30/05

    Outputs
    Molecular genetics has given plant pathologists new tools that allow characterization of pathogens and their hosts at the species, population, and individual level. Information on the population structure of the rust (Cronartium ribicola), hosts (5-needle pines), and alternate hosts (Ribes, Castilleja, and Pedicularis) are necessary to develop management practices and tools such as establishment of resistant trees, efficient rust-resistance screening, and predicting infection rates. Molecular genetics can help answer questions such as "Does a rust population on the leading edge of spread tend to be more aggressive and genetically uniform?", "Have rust populations that exist near sites of introduction become less aggressive and more genetically diverse over time?", and "Are there different races of the rust that may be host-specific and/or alternate host-specific?".

    Impacts
    An understanding of the genetic structure of blister rust pathosystems will help us restore stable ecosystems containing 5-needle pines.

    Publications

    • Richardson, B., N. B. Klopfenstein, and T. L. Peever. 2005. Assessing forest-pathogen interactions at the population level. In: Forest Pathology: from Genes to Landscapes. Lundquist, J., and R. Hamelin, eds. American Phytopathological Society Press, Minnaepolis, MN. p 21-30.


    Progress 10/01/03 to 09/30/04

    Outputs
    Studies on the ecological genetics of whitebark pine continue. Preliminary analysis of the data shows that a genetic structure relevant to climate is detectible for whitebark pine. This means that seed transfer distances for whitebark pine would likely be fairly generous. In addition, the genetic structure of white pine blister rust is being investigated.

    Impacts
    Knowledge of ecological and population genetics of the host and pathogen will be useful for host resistance screening, gene deployment, and predicting pathogen adaptation. Such knowledge would facilitate faster recovery of five-needle pines by 1) increasing host resistance and fitness, 2) decreasing pathogen aggressiveness, and 3) enhancing natural regeneration.

    Publications

    • No publications reported this period


    Progress 10/01/02 to 09/30/03

    Outputs
    Cronartium ribicola, the causal agent of white pine blister rust (WPBR), has been a major contributor to the decline of five-needle pines in North America. Since its introduction into western North America nearly 100 years ago, C. ribicola has spread from Vancouver, B.C. to Wyoming and New Mexico infecting numerous five-needle pine species. WPBR has contributed in changing these ecosystems by altering forest species composition. The present forests, where five-needle pines once predominated, are now composed of mainly climax species. This change has generally resulted in more disease/insect activity and higher fuel loads, which has left many our western forests in a state of increased fire intensity. Restoration of white pine ecosystems requires information and management of both pathogen and the host. Limited information is available on the adaptive and genetic changes that enables C. ribicola to infect multiple host species across an extremely heterogeneous environment. An ecological genetics study continues on whitebark pine to determine adaptability limits of populations within the species. If seed is transferred too far from its origin, the seedlings will be maladapted to the new site. Third-year growth measurements were recorded on whitebark pine seedlings planted in two common garden test plots. Results will apply to sites in the northern Rocky Mountains.

    Impacts
    Knowledge of ecological and population genetics of the host and pathogen will be useful for host resistance screening, gene deployment, and predicting pathogen adaptation. Such knowledge would facilitate faster recovery of five-needle pines by 1) increasing host resistance and fitness, 2) decreasing pathogen aggressiveness, and 3) enhancing natural regeneration.

    Publications

    • No publications reported this period


    Progress 10/01/01 to 09/30/02

    Outputs
    White Pine Blister rust was inadvertently introduced to western North America in 1910. Very few pines were resistant to the disease as mortality spread across the West. Today, less than 10 percent of the historic 5 million acres of the Western White Pine cover type remains in Inland Northwest forests, and mortality is similar for Whitebark Pine. The forests that replaced white pines are more prone to diseases and insects; in addition, today's forests are missing keystone species that determine the ability of other plant and animal species to persist in the community. Genetic resistance in western white pine to blister rust has been demonstrated, and a breeding program based on this resistance has developed western white pine seedlings that are about 66 percent resistant. Further development will bring resistance to about 80 percent. Surveys in test plantations show consistently lower infection and mortality in genetically improved Western White Pine compared to unimproved stock. Even at the site where 93 percent of genetically improved stock was infected, 34 percent of these improved trees were still alive at age 26, while 100 percent of the unimproved stock had died by age 12. Growing genetically improved Western White Pine seedlings for more than 25 years under field conditions has demonstrated the stability of resistance under annually varying infection conditions. In high elevation Whitebark Pine stands, Clark's nutcracker readily disperses seed throughout individual stands. However, DNA data indicates that nutcrackers rarely disperse seed across large forest gaps. Genetic structure of Whitebark Pine stands throughout the Inland Northwest indicates that information on seed movement could provide one method for recovery of Whitebark Pine ecosystems. Cooperative research continues with the Inland Empire Tree Improvement Cooperative, Forest Service Northern Region, the University of Idaho, and various land management agencies. The white pine breeding program will work to incorporate additional resistance mechanisms into white pine seedlings and develop cultural treatments that promote the growth and survival of white pine. We can restore our white pine ecosystems to health and vigor, but this will take a concerted effort among forest managers in the Inland Northwest.

    Impacts
    These new resarch findings will facilitate and encourage the restoration of western white pine and whitebark pine ecosystems.

    Publications

    • Fins, Lauren; Byler, James; Ferguson, Dennis; Harvey, Al; Mahalovich, Mary Frances; McDonald, Geral. 2002. Return of the giants: restoring western white pine to the Inland Northwest. Journal of Forestry. 100(4): 20-26. Additional authors: Miller, Dan; Schwandt, John; Zack, Art.
    • Richardson, B.A.; Brunsfeld, S.J.; Klopfenstein, N.B. 2001. DNA from bird-dispersed seed and wind-disseminated pollen provides insights into postglacial colonization and population genetic structure of whitebark pine. Molecular Ecology. 11(October): 214-227.
    • Richardson, B.A.; Brunsfeld, S.J.; Klopfenstein, N.B. 2001. DNA from bird-dispersed seed and wind-disseminated pollen provides insights into postglacial colonization and population genetic structure of whitebark pine. Molecular Ecology. 11(October): 214-227.