Identification of Two Sweet Potato Feathery Mottle Virus Strains in North Carolina. J. W. Moyer, Assistant Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650. B. B. Cali, Graduate Student, Department of Plant Pathology, and G. G. Kennedy, Associate Professor, Department of Entomology, North Carolina State University, Raleigh 27650; and M. F. Abou-Ghadir, Faculty of Agriculture, University of Assiut, Egypt. Plant Dis. 64:762-764. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-762.

A survey of commercial sweet potato fields showed two widely distributed strains of sweet potato feathery mottle virus (FMV). One strain caused only foliar symptoms in sweet potato (Ipomoea batatas ‘Jersey’); the other, RC-FMV, caused the russet crack disease on Jersey roots. The two strains were further distinguished by foliar symptoms produced in I. nil and I. purpurea and by local lesion development on Chenopodium amaranticolor or C. quinoa by RC-FMV. The FMV strain did not infect Chenopodium spp. Foliar symptoms in Jersey and Jewel cultivars and other Ipomoea spp. consisted of chlorotic vein banding and chlorotic spotting for both strains. The two strains were serologically related in microprecipitin tests, had thermal inactivation points of 60–65 C, dilution end points of 10^–3 to 10^–4, and longevities in sap of less than 1 day. These studies support previous findings that the russet crack virus is a strain of FMV.