Stem Canker of Sweet Potato Induced by Fusarium solani. J. W. Moyer, Associate Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650. C. L. Campbell, Assistant Professor, and C. W. Averre, Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27650. Plant Dis. 66:65-66. Accepted for publication 6 September 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-65.

A new disease of sweet potato (Ipomoea batatas) stems and roots observed on two farms in North Carolina in 1978 had spread more extensively by 1980. Stems were swollen and ruptured near the soil line with a firm, dark brown to black lesion extending from the stem into the pith of tuberous roots. Inoculation of stems and tuberous roots with single conidial isolates of Fusarium solani obtained from naturally infected stems resulted in symptoms similar to those observed in the field. Cankers at the soil line extended up to 7.5 cm from the base of the stem (point of attachment to the root). Bioassays demonstrated that colonization occurred in advance of the canker. Necrotic lesions were present on 20 of 60 sprouts produced from infected roots; F. solani was isolated from all symptomatic sprouts, from 26 of 40 symptomless sprouts, and from all symptomatic fibrous roots. A survey 4–5 mo after harvest revealed the presence of the Fusarium stem-rotting pathogen in tuberous roots at seven of 17 storage facilities. “Seed” roots may be a source of initial inoculum for F. solani infection.

Keyword(s):