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Project ID: 11-S-2-6

Year: 2012

Date Started: 06/01/2012

Date Completed: 04/05/2016

Title: Enhancing the Effectiveness of Annual Grass Weed Biocontrol with the Seed Pathogen Black Fingers of Death (Pyrenophora semeniperda) on Intermountain Rangelands

Project Proposal Abstract: Annual brome infestation, especially cheatgrass (Bromus tectorum) infestation, is a major contributing cause of environmental degradation on tens of millions of hectares of semiarid rangelands in the Interior West, where repeated burning often results in conversion to annual grass-dominated systems. Annual brome monocultures are very difficult to restore to more desirable perennial vegetation without some form of control, and even effective control of existing annual brome stands can leave behind high seed densities in the persistent seed bank. Our project has the primary goal of developing a biocontrol method that specifically targets these dormant, ungerminated seeds. The fungal seed pathogen black fingers of death (Pyrenophora semeniperda) kills thousands of seeds per square meter every year in seed banks of weedy annual bromes, even at naturally occurring levels. We have shown that augmentation with artificially produced inoculum of this pathogen can result in elimination or near-elimination of the annual brome persistent seed bank. Use of this biocontrol agent in combination with herbicides that eliminate germinated seeds or plants can result in essentially complete control. A second goal of our research is to determine whether it might be possible to use this biocontrol method to provide quick knock-down control of germinable seeds. A sizeable fraction of the non-dormant seed bank is also killed by biocontrol treatments with this pathogen, suggesting that it may be possible to use this organism in place of herbicides, if highly effective strains can be found. Use of this biocontrol organism can potentially be incorporated into post-fire and restoration seeding projects in areas dominated by annual bromes, greatly improving chances of success. Our research project has three principal objectives: 1) Determine biocontrol efficacy against cheatgrass under realistic restoration scenarios in the field in terms of native grass emergence, establishment, and survival, 2) Systematically evaluate among-strain variation in virulence, growth rate, phytotoxin production, and environmental tolerance, and determine how these traits affect biocontrol efficacy, in order to select highly effective strains to use for biocontrol, and 3) Evaluate the potential effectiveness of this pathogen for control of other important annual grass weeds. For the field inoculation studies at former Wyoming big sagebrush sites in Utah, Idaho, and Washington, we will apply biocontrol treatments and plant native grass seeds on two dates in precision seeding studies, then follow establishment success across two years. For the strain trials, we will use techniques and procedures we have developed in our earlier studies to obtain pure cultures of pathogen strains from field-infected cheatgrass seeds, increase conidial inoculum of these strains, screen for virulence, growth rate, phytotoxin production, and environmental tolerance, and evaluate biocontrol efficacy in greenhouse and growth chamber bioassays. We will also obtain pathogen strains from five other important annual grass weeds: red brome, Japanese brome (B. arvensis), jointed goatgrass (Aegilops cylindrica), medusahead (Taeniatherum caput-medusae), and Africagrass (Ventenata dubia). All of these grasses are known hosts of the black fingers of death pathogen. We will test these strains in cross-inoculation trials to determine the level of susceptibility of these species to different pathogen strains and whether host-adapted strains would provide better biocontrol than strains specifically selected for use on cheatgrass.

Principal Investigator: Susan E. Meyer

Agency/Organization: Forest Service

Branch or Dept: RMRS-Shrub Sciences Laboratory

Other Project Collaborators




Branch or Dept

Agreements Contact

Susan T. Major

Forest Service

RMRS-Rocky Mountain Research Station

Budget Contact

Edith M. Cates

Forest Service

RMRS-Rocky Mountain Research Station

Co-Principal Investigator

Phil S. Allen

Brigham Young University

Department of Plant & Wildlife Sciences

Co-Principal Investigator

Julie Beckstead

Gonzaga University

Department of Biology

Funding Cooperator

Susan E. Meyer

Forest Service

RMRS-Shrub Sciences Laboratory

Project Locations

Fire Science Exchange Network

Great Basin









West Desert District




Columbia National Wildlife Refuge




Twin Falls District

Project Deliverables

Final Report view or print

("Results presented in JFSP Final Reports may not have been peer-reviewed and should be interpreted as tentative until published in a peer-reviewed source.")

  ID Type Title
view or print   102 Book Chapters in Compiled Works Community ecology of fungal pathogens on Bromus tectorum
view or print   3562 Journal Article Plant Ecology
view or print   3563 Journal Article Journal of Natural Products
view or print   3564 Journal Article Tetrahedron
view or print   3565 Journal Article Journal of Agricultural and Food Chemistry
view or print   3566 Journal Article Plant Pathology
view or print   3682 Journal Article Rangeland Ecology and Management
    3686 Journal Article American Journal of Botany
view or print   3684 Journal Article Mycologia
view or print   3685 Journal Article Seed Science Research
view or print   3687 Journal Article Fungal Biology
view or print   3688 Journal Article PLoS One
    3689 Journal Article Biological Invasions
view or print   3429 Journal Article Invasive Plant Science and Management
view or print   3430 Journal Article Oecologia
view or print   3431 Journal Article Biocontrol Science and Technology
    3428 Journal Article Seed Science Research
view or print   344 MS Thesis Population genetic structure of Bromus tectorum in the American Desert Southwest
view or print   345 MS Thesis Secondary dormancy and summer conditions influence outcomes in the P semeniperda - B tectorum patho
view or print go to website 346 MS Thesis Mating type locus characterization and variation in Pyrenophora semeniperda.
    318 MS Thesis The Bromus tectorum-Pyrenophora semeniperda Pathosystem

Supporting Documents

There are no supporting documents available for this project.

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