Page Banner

United States Department of Agriculture

Agricultural Research Service

Related Topics


Location: Foreign Disease-weed Science Research

Project Number: 8044-22000-039-00-D
Project Type: Appropriated

Start Date: Oct 1, 2010
End Date: Sep 30, 2015

1. Discover, identify and evaluate the efficacy of exotic pathogens as classical biological control agents of invasive weeds such as Canada thistle, Russian thistle, Russian knapweed, yellow starthistle, and medusahead. 1A - Discovery 1B - Isolation and identification 1C - Evaluation of pathogen efficacy 2. Conduct risk analyses to determine the agricultural and ecological safety for the release of pathogens as classical biological control agents, such as Colletotrichum gloeosporioides f. sp. salsolae and Phoma exigua. 2A - Development of test plant lists 2B - Evaluation of disease reaction among non-target and target species 3. Develop an improved process of risk assessment using plant pathogens as a model system. 3A - Integrate DNA sequences of species on the basic test plant list into host- range evaluation with Mixed Model Equations 3B - Generate BLUPs of species on the basic test plant list 3C - Determine true host range of each pathogen by including DNA sequences and disease reaction data of other closely related species. 4. Release and, with collaborators, monitor and evaluate impact of pathogens on weed populations and non-target effects in the field. 4A - Develop and submit a proposal for release that describes the importance of the target weed as a pest and the efficacy and safety of the candidate pathogen. 4B - Participate in the regulatory decision process as needed. 4C - Participate with cooperators in release (with permit from state and federal regulators) and post-release monitoring of the pathogen).

Exotic pathogens will be collected from symptomatic target weeds in countries where they are native, evaluated for their potential using standard plant pathology methods, and identified using both classical morphological characters and molecular sequence data. The primary target weeds will be Canada thistle, Russian thistle, Russian knapweed, yellow starthistle, and medusahead. Other targets include, but are not limited to: Carduus thistles, milk thistle, knapweeds, common crupina, whitetop, broadleaved pepperweed, Himalaya blackberry, swallow-worts, cheat grass, teasel, and field and hedge bindweed. Pathogens will be evaluated for the risk associated with intended release into ecosystems containing economically and ecologically important North American plant species. Risk will be evaluated, in quarantine, based on disease reaction of species related to the target weed from a test-plant list reviewed and modified according to recommendations of regulators at the USDA Animal and Plant Health Inspection Service. In evaluating disease reaction, an improved method of risk assessment will be developed and used. This improved method incorporates disease reaction data with genetic relatedness, from DNA sequences, of species on the test-plant list. Output from these analyses will be best linear unbiased predictors of the disease reaction of each species. Pathogens determined to have an adequately narrow host range will be proposed for release in the U.S.A. Proposals for release of the pathogen will be developed for review by the Technical Advisory Group for Biological Control Agents of Weeds, and subsequent development of an Environmental Assessment, declaration of Finding of No Significant Impact and issuance of federal and state permits for release. Inoculum of the pathogen will be prepared in sufficient quantity for release, and target weeds will be inoculated in the field under conditions that favor disease development and establishment. Establishment and spread of pathogens will be monitored in the field by recording disease symptoms on the target weed and re-isolating the pathogens. Damage to target weed populations and environmental factors important in pathogen establishment, efficacy and spread, will be measured.

Last Modified: 2/23/2016
Footer Content Back to Top of Page