Field Evaluation of Sweet Potato Clones for Reaction to Root-Knot and Stubby Root Nematodes in California

Abstract

Clones of ‘Jewel’, ‘Eureka’, ‘Pope’, ‘Oklamex’, ‘Garnet’, L5-19, NC-719, and W-152 sweet potato [ Ipomoea batatas (L.) Lam] were tested for 1 to 3 seasons in field plots of coarse-textured sand soils. The soils were infested with Meloidogyne incognita (Kofoid & White) Chitwood and Paratrichodorus minor (Colbran) Siddiqui that included 1,3-dichloropropene fumigated and nonfumigated subplots. ‘Jewel’, followed by ‘Pope’, was the highest-yielding copper-skinned type and the least affected by nematode infection; however, it supported large numbers of M. incognita . Yields of ‘Eureka’ were lowest in nonfumigated plots in the presence of P. minor . Significantly greater P. minor population increase occurred on ‘Eureka’ than on other clones. Yield of red-skinned W-152 was greater than ‘Garnet’ on fumigated plots, but W-152 showed no greater yield when nematode-infected. ‘Oklamex’, L5-19, and NC-719 were discontinued after 1 year because of poor yield or quality. M. incognita resistance in all clones prevented damage to the appearance of sweet potatoes, but plant growth and yield were increased significantly in fumigated plots compared with yields from nonfumigated plots. M. incognita reproduced on all lines, especially when soil temperature was high in 1981.