Oregon State University

Awards Issued Prior to January 20, 2025, Were Funded Under Previous Administrations and May Not Reflect the Priorities and Policies of the Current Administration. Carrots (daucus Carota Subsp. Sativus) Are One of the United STATES' Leading Root Crops. the 2018 Farm-gate Value of Carrots in the U.s. Was $731,504,000 and Average Per Capita Consumption of Fresh Carrots in the U.s. Is 12.4 LB. Per Person. Carrot Seed Production Is Limited to Only a Few Regions of the World Where Suitable Climatic Conditions Exist for Hybrid Seed Production of This Biennial Species. in Fact, Over 50% of the WORLD'S Hybrid Carrot Seed Is Produced in Central Oregon, Central Washington, Southern Idaho, and Northern California of the U.s. Pacific Northwest Region. Stakeholders Have Consistently Identified Bacterial Blight Caused by Xanthomonas Hortorum PV. Carotae (XHC) as the Most Significant Threat to the Sustainability and Economic Viability of Us Carrot Seed Production. However, Because XHC Is Seed-borne, It Is Not Only a Major Concern for the Hybrid Carrot Seed Industry in the U.s. But Also to Regions That Import Carrot Seed for Fresh or Processed Carrot Production. XHC Can Survive and Reproduce Epiphytically on the Leaves, Flowers, and Stems of Host and Non-host Plants Without Causing Disease Symptoms. When Weather Conditions Are Sufficiently Warm and Humid, XHC Can Incite Disease, Which Can Lead to Defoliation and Significant Yield Losses. in the Case of Bacterial Blight, Symptoms Are Often Not Observed on Carrots Until a Relatively High Population Is Attained (> 104 XHC/G Leaf Tissue). One Reason Why XHC Is So Problematic in Carrot and Carrot Seed Production Is That the Process by Which the Pathogen Infects Plants and Infests Seeds Is Largely Unknown. Critical Needs Associated With Bacterial Blight in Carrot and Carrot Seed Include: I) Improving Disease Control in the Field and Post-harvest; Ii) Learning How XHC Spreads in Seed Production Systems; Iii) Determining If Carrot Seed Becomes Infested Externally, Infected Internally, or Both; Iv) Identifying Sources of XHC in Production Systems and Quantifying the Extent of Inoculum Dissemination via Propagative Materials; and V) Quantifying the Impact of Bacterial Blight on Yield And/or Quality of Carrot Seed, as Well as the Costs Associated With Mitigation of These Effects.we Propose to Use a Transdisciplinary Research Approach, Deeply Integrated With Extension and Outreach, to Address These Critical Needs. for Objective 1, We Will Evaluate and Implement Sustainable Integrated Pest Management (IPM) Approaches for Bacterial Blight in Carrot and Carrot Seed Crops. to Improve XHC Ipm in the Field We Will Identify Cultural Practices That Reduce XHC Survival and Sources of Inoculum, Screen Natural Compounds and Biorational Products for the Biocontrol of XHC, and Assess a Multi-pronged Ipm Approach. We Will Also Test Complementary Approaches That Can Be Used With Existing Post-harvest Seed Disinfestation Practices. in Objective 2, We Will Identify and Model Environmental Factors and Physical Processes Related to XHC Aerobiology and Epidemiology. to Understand XHC and General Bacterial Aerobiology at Multiple Scales, We Will Determine the Particle Sizes, Agriculture Events, and Environmental Conditions Associated With XHC Aerial Dispersion and Develop or Adapt Transport Models That Accurately Describe Pathogen Dispersion Between and Within Fields. the Goal of Objective 3 Is to Characterize the Nature and Extent of XHC Colonization in Carrots to Inform and Enable More Precise and Effective Control Measures. We Will Use Various Microscopy Methods (light, Laser Confocal Fluorescence, and Scanning Electron Microscopy) to Trace the XHC Infection Process and Gain Insights Into Where the Pathogen Colonizes Plants, When and Where XHC Initiates Infection, and How the Pathogen Infests Seeds. We Will Use Population Genomics Approaches in Objective 4 to Identify Sources of Bacterial Blight Inoculum and Dispersal Potential of XHC in Carrot and Carrot Seed Production Systems. the Genomic Diversity of XHC From U.s. and International Carrot and Carrot Seed Production Areas, Wild Carrot Populations, Propagative Materials, Environmental Samples, and Historical Collections Will Be Determined and This Information Will Be Used to Model Transmission Chains and Inoculum Sources. Finally, the Activities in Objective 5 Will Calculate the Economic Impact of Bacterial Blight and Associated Management Practices on Carrot Seed Stakeholders. Outreach and Extension Are Integrated Throughout the Project.this Project Will Address Multiple Goals That Will Lead to Actionable Items That Can Be Implemented in the Short-, Medium-, and Long-term in Both Conventional and Organic Systems. the Proposed Activities Will Foster Changes in Practices, Increase the Number and Efficacy of Bacterial Blight Control Methods, and Introduce Potentially Transformative Technologies That Can Be Used at Different Stages in the Process of Carrot Seed and Root Production. the Expected Deliverables Resulting From This Project Include: I) Enhanced Ipm Approaches for Bacterial Blight Control Inthe Field and Post-harvest; Ii) Particle Transport Models That Explain Factors Associated With XHC Dispersal; Iii) an Understanding of Plant and Seed Infection Processes to Inform Future Management Strategies; Iv) Identification of Sources and Transmission Pathways of XHC in Carrot Production Systems for Targeted Mitigation Efforts; and V) an Economic Analyses of the Costs and Benefits Associated With Bacterial Blight and Related Ipm Efforts to Guide Future Stakeholder Decisions. Our Long-term Goal Is to Develop a Suite of Ipm Approaches for the Carrot Industry to Reduce Risks Associated With Bacterial Blight Caused by XHC. an Integrated Approach Towards Mitigating XHC Will Reduce Industry Reliance on Hot Water Treatment of Seed Lots, Which Is Expensive and Difficult to Perform at Large Scales, Reduce Economic Losses by Limiting the Number of Seed Lots Rejected at Ports of Entry, and Increase Agricultural Income and Associated Activities in Rural Areas in Which Carrot and Carrot Seedsare Produced. in Carrot and Carrot Seed Production, It Is Anticipated That an Ipm Approach Will Decrease Copper Use Thus Reducing the Indirect Impacts to Soil and the Water Table and Direct Impacts to Bees, Native Pollinators, and Other Beneficial Microorganisms That Promote the Health of Crop Plants. a Sustainable Carrot Seed Supply Is Required to Continue Production of This Nutritious and Popular Vegetable, and the Grower Community Will Benefit Through an Enhanced Understanding and Applications of Ipm Approaches.