Sweetpotatoes: Testing traits for increased market value and sustainable production for direct market farms in the maritime northwest

Project Overview

Project Type: Research and Education
Funds awarded in 2023: $313,125.00
Projected End Date: 04/01/2026
Host Institution Award ID: G293-23-W9981
Grant Recipient: WSU Extension Regional Small Farms Program
Region: Western
State: Washington
Principal Investigator:
Laurel Moulton
WSU Extension Regional Small Farms Program
Dr. Carol Miles
WSU Mount Vernon NWREC
Clea Rome
Washington State University

Information Products


  • Vegetables: sweet potatoes


  • Crop Production: varieties and cultivars
  • Pest Management: integrated pest management

    Proposal abstract:

    Recent studies have shown that Sweetpotato (Ipomoea batatas) yields in the northern United States can be the same or greater than the national average. Small organic growers in western Washington have started to experiment with growing them in a maritime climate with varying results. In Washington, wireworm damage reduces the marketability of sweetpotato storage roots. However, there are advanced breeding lines with wireworm resistance, and we have tested these in preliminary trials at WSU Mount Vernon NWREC and now have adequate numbers of roots to propagate for field trials.  

    The research project will investigate the efficacy of wireworm-resistant sweetpotato advanced breeding lines in western Washington, assess the yield potential of sweetpotato cultivars, and develop sweetpotato production guidelines for growers in western Washington State. These research objectives will be accomplished through on-station and on-farm trials. Results will help determine the potential of sweetpotato as a high-value and unique crop for direct market farmers in the maritime climates of the Olympic and Kitsap Peninsulas in Washington State.   

    Creating this project partnership between local producers and Extension researchers will benefit farmers by facilitating access to newly released sweetpotato varieties from USDA-ARS that show resistance to wireworm damage and have other traits that may have benefit to the small organic farm beyond those traits found in commercially available varieties. Data from on-station trials and input from participating farmers may contribute to the public release of additional sweetpotato lines that have superior qualities for the maritime northwest and that would not be prioritized for release when only trialed in traditional growing regions. The project will also create a platform for information sharing between producers to speed the process in finding the most sustainable and efficient production methods for our maritime climate. Educational opportunities facilitated by Extension educators will help bring research findings and farmer innovation to the broader western Washington area. Education and outreach will include on-farm workshops and field days, online seminars, publication of fact sheets and presentation of results at regional conferences. We will also share results with our research and Extension peers through journal articles. 

    Project objectives from proposal:

    Research objectives:

    1. Investigate the efficacy of wireworm-resistant sweetpotato advanced breeding lines in western Washington. Assess the yield potential of sweetpotato cultivars and advanced breeding lines with soil-warming mulch. 
    2. Develop sweetpotato production guidelines for growers in western Washington State. 

    Education objectives:

    1. Hold two on-farm field days per project year (6 total) to view trial results, share innovative techniques that individual farmers develop for propagating, producing, curing/storage or marketing sweetpotatoes in a cool maritime climate.  
    2. Hold online (Zoom) farmer to farmer discussion sessions on growing sweetpotatoes.  Public events will occur as a part of the regular WSU Regional Small Farms “Dirt Talk” series. Dirt Talk is hosted by WSU Regional Small Farms in conjunction with a local farmer or agriculture specialist willing to share their expertise in a given topic. Events are held in a supportive yet informal atmosphere, that allows participants to share, exchange perspectives, and learn from each other without pressure. Events are open to all new and current farmers. Dirt Talk events are recorded and posted on the Regional Small Farms website for future viewing. Project team events include an annual end of season meeting to troubleshoot, assess success/failure and inform changes to the project in the following season.
    3. Update Extension fact sheets that were created in preliminary research. Fact sheets include sweetpotato slip production, field production practices, and curing and storage. Updates will be based on trial results and farmer feedback. Fact sheets will be made available on the WSU Extension Publication website and other Extension outlets and translated into Spanish.
    4. Present results to research peers at the American Society of Horticultural Science (ASHS) annual conference and to regional growers at Washington Farming and Agriculture Tilth Conference.
    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.