Orange-fleshed sweetpotato (Ipomoea batatas) cultivars with moist, sweet texture are the most popular type of sweetpotatoes grown in the United States, while elsewhere in the world, white, yellow, and purple-fleshed types with firm, dry texture are more popular. There is a market opportunity in the United States for diverse sweetpotato cultivars, however, their yield tends to be low as they have not received the same breeding attention as orange-fleshed cultivars. In this experiment, six advanced breeding lines from the USDA, representing a diversity of flesh colors, textures, sweetness, and firmness, were compared to cvs. Covington (standard) and Cascade (new release). The experiment was carried out in a certified organic field in Mount Vernon, WA in 2024 and is being repeated in 2025. Each plot included 15 plants with 4 replicate blocks. In 2024, sweetpotatoes were planted on 4 June in raised beds covered with black polyethylene mulch and with drip irrigation. Harvest was by hand on 7 Oct., roots were sorted by size, and damage by wireworms (Agriotes lineatus, A. obscurus, Limonius canus), the most significant insect pest impacting sweetpotatoes in this region, was assessed using the WDS severity index ( 0 = no scars, 1 = 1-5 scars, 2 = 6-10 scars, 4 = >10 scars). Without accounting for wireworm damage, yield (US No. 1 and US No. 2) of ‘Covington’ (orange, soft flesh) was highest (18.2 t/ha) followed by USDA-22-009 (13.8 t/ha, yellow flesh), and ‘Cascade’ (white, firm flesh) had low yield (6.7 t/ha) followed by purple-fleshed breeding lines USDA-17-090 (4.1 t/ha) and USDA-16-051 (3.1 t/ha). Orange-fleshed breeding lines USDA-16-031 (3.8 t/ha) and USDA-19-036 (1.7 t/ha) and yellow-fleshed USDA-23-039 (0.5 t/ha) all had low yield. ‘Cascade’ was the most wireworm resistant (WDS severity index 1.61) followed by USDA-16-051 (2.33), while ‘Covington’ and USDA-22-009 were the most susceptible (3.67 and 3.54, respectively). The breeding lines USDA-16-031, USDA-17-090, USDA-19-036, and USDA-23-039 had similar ratings, ranging from 2.83 to 3.39. While yields of ‘Cascade’ (white, firm flesh) and USDA-16-051 (purple flesh) were less than ‘Covington’, farmers may be interested in growing these niche cultivars for their wireworm resistance and to cater to consumer interests.
