UH has nation’s clean seed lab for Okinawan sweetpotatoes

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Tucked away at the University of Hawaiʻi at Manoa's Komohana facility in Hilo, a small team of researchers from the College of Tropical Agriculture and Human Resilience (CTAHR) is building the clean seed pipeline that could help secure the future of the state's sweetpotato industry. Clean seeds are vine cuttings that are free from harmful viruses.

The National Clean Plant Network (NCPN) Sweetpotato-Hawaiʻi Center is part of the USDA-supported NCPN-Sweetpotatoes program, a national network of clean plant centers, scientists, regulators, and growers. It is the only center in the network dedicated to Okinawan and Hawaiian heritage ʻuala (sweetpotatoes).

The center combines advanced tissue culture and diagnostics with strong partnerships among farmers, researchers, and cultural practitioners. Together, they are laying the groundwork for a reliable, local system for ʻuala and Okinawan sweetpotato health.

Hawaiʻi's sweetpotatoes

While programs on the U.S. continent work with orange-fleshed varieties, the Hawaiʻi center, led by CTAHR Extension Agent Sharon Wages, prioritizes purple-fleshed Okinawan types and traditional ʻuala that are central to local diets and markets.

"Hawaiʻi has the corner on Okinawan sweetpotato in the U.S.," she said, noting that continental U.S. climates often cannot match the crop's performance in Hawaiʻi's tropical weather.

Sweetpotato (Ipomoea batatas) is a major crop in Hawaiʻi, with 6.2 million pounds grown here in 2025, according to the USDA. Nine out of 10 ʻuala are produced on Hawaiʻi Island, particularly along the Hāmākua Coast.

Establishing a virus-free foundation

Supported by researchers Achyut Adhikari and Elisa Urano Mow, a tissue culture specialist, the sweetpotato center uses meristem-tip tissue culture to clean infected plant lines for each kind of ʻulua and establish virus-free foundation material for growers. This clean stock can then be multiplied and distributed, giving farmers a healthier starting point for new plantings.

While all NCPN centers follow a standard virus testing protocol, CTAHR researcher Anna Halpin-McCormick has documented additional viruses in the state. The Hawaiʻi center is now incorporating two of these locally significant viruses into its regular diagnostics, strengthening protection against region-specific threats.

The center has 11 unique sweetpotato varieties. The staff works closely with local growers to advance lines that are both nutritious and marketable, including several Okinawan-type selections and important heritage ʻuala.