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

View the project final report

Commodities

• Vegetables: sweet potatoes

Practices

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

Our study has shown that sweetpotato (Ipomoea batatas) yields in our northern region of the United States can be the same or greater than the national average. Small organic growers in western Washington started to grow and market sweetpotatoes due to this project. In Washington, wireworm damage reduces the marketability of sweetpotato storage roots. We identified cultivars and advanced breeding lines with wireworm resistance, and we distributed these as well as high-yielding susceptible cultivars to growers who have varying levels of wireworm pressure. 

Our research project screened sweetpotato advanced breeding lines and varieties for wireworm resistance in western Washington, assessed the yield potential for sweetpotato, and developed production guidelines for growers in western Washington State. These research objectives were accomplished through on-station and on-farm trials. Results have helped determine the potential of sweetpotato as a high-value and unique crop for direct market farmers in the maritime climates of northwest Washington State.  

Creating our project partnership between local producers, Extension and researchers benefited farmers by providing access to newly released sweetpotato varieties from USDA-ARS that show resistance to wireworm and have other traits that may benefit small-scale organic farmers beyond those traits found in commercially available varieties. Data from on-station trials and input from participating farmers contributed to the public release of new sweetpotato lines that have qualities that would not be prioritized in traditional growing regions. The project created a platform for information sharing among producers to speed the process in finding the most sustainable and efficient production methods for our maritime climate. Educational opportunities facilitated by Extension educators delivered research findings and farmer innovation to the broader western Washington area. Education and outreach included on-farm workshops and field days, online seminars, publication of fact sheets and presentation of results at regional conferences. We shared results with our research and Extension peers through national conferences and journal articles.

Research objectives:

1. Investigate the efficacy of wireworm-resistant sweetpotato advanced breeding lines in western Washington.  Assess the yield potential of sweetpotato varieties 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.