2019 ASHS Annual Conference

In recent years damage by both sweetpotato weevil (Cylas formicarius) and the newly introduced rough sweetpotato weevil (Blosyrus asellus) has negatively impacted the quality of sweetpotatoes (Ipomoea batatas ssp. batatas) grown for the Hawaiian export market. Demand for the purple-fleshed, white-skinned ‘Okinawan’ cultivar, which performs particularly well in Hawaiʻi, has increased due to public interest in its antioxidant potential and coverage from popular celebrities. While this cultivar is well-adapted to Hawaiian conditions it is susceptible to rough weevil damage, which makes the tuberous roots visually unappealing. It appears to have some resistance to sweetpotato weevil damage, perhaps through the location of storage roots deep into the soil, but still suffers noticeable damage and the damaged tuberous roots become inedible. We conducted a replicated trial of 10 cultivars/accessions which were previously reported to possess weevil resistance, as well as ‘Okinawan’ as a control. Significant differences existed among cultivars/accessions for damage from both regular and rough sweetpotato weevils, as well as for other agronomic and culinary characteristics. A second trial encompassing 18 cultivars/accessions, including the best performers from the first trial, is currently underway. These trials experienced outbreaks of sweetpotato scab (Elsinoë batatas) and leaf miners (Bedellia somnulentella), with the cultivars/accessions showing a range of responses to these cultivation challenges as well. Promising cultivars/accessions are being used to develop a breeding program that incorporates the identified resistance and other traits into an ‘Okinawan’ background.