Disease Note.

Occurrence of Sweetpotato Chlorotic Leaf Distortion in Brazil and Peru Caused by Fusarium lateritium. T. Icochea, Centro Internacional de la Papa, Apartado 5969, Lima, Peru. V. Duarte, Faculdade de Agronomia, UFRGS, Caixa Postal 776, Porto Alegre, RS, Brazil 90012-970; and C. A. Clark, Department of Plant Pathology & Crop Physiology, Louisiana Agricultural Experiment Station, LSU Agric. Center, Baton Rouge 70803-1720. Plant Dis. 78:754. Accepted for publication 15 April 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0754D.

Chlorotic leaf distortion (CLD) of sweetpotato (Ipomoea batatas (L.) Lam), which was first reported from Louisiana (I), was observed on sweetpotato cultivars Brazlandia Branca, Brazlandia Rosa, and Brazlandia Roxa but not on 25 other sweetpotato cultivars growing in experimental fields in southern Brazil from February to May, 1993. In Peru, symptomatic plants were observed in fields along the coast. Symptoms included delayed unfolding of leaves, distortion and raised veins on young leaves, and interveinal chlorosis on mature leaves. A white, waxy-appearing substance occurred over the adaxial leaf surface and was concentrated on or near the leaf margins. It consisted of mycelia, macroconidia, and microconidia of Fusariuin lateritium Nees:Fr. (2). This pathogen was readily isolated from the leaf surface and grew well on potato dextrose agar. Isolates of F. lateritium also were obtained from true seed of sweetpotato produced in Brazil and Peru. Of 11 seed isolates, one from Brazil induced the full CLD syndrome in the greenhouse after inoculation to CLD-free mericlones of sweetpotato clone NC-845. Five seed isolates from Brazil and both seed isolates from Peru grew systemically on the surface of sweetpotato vines but did not induce chlorosis, and the remaining three isolates from Brazil did not colonize sweetpotato vines or induce symptoms.