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Etiology

Fusarium lateritium, Causal Agent of Sweetpotato Chlorotic Leaf Distortion. C. A. Clark, Professor, Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, LSU Agricultural Center, Baton Rouge 70803-1720; R. A. Valverde(2), J. A. Wilder-Ayers(3), and P. E. Nelson(4). (2)(3)Assistant professor, and Research associate, respectively, Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, LSU Agricultural Center, Baton Rouge 70803-1720; (4)Professor, The Fusarium Research Center, Department of Plant Pathology, The Pennsylvania State University, University Park 16802. Phytopathology 80:741-744. Accepted for publication 6 February 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-741.

Symptoms and signs of chlorotic leaf distortion of sweetpotato (Ipomoea batatas) include a white superficial growth consisting of fungal hyphae and macroconidia of Fusarium on young leaves, followed by general chlorosis and, in some instances, twisting and distortion of leaves. Fusarium lateritium was isolated from all symptomatic plants and many symptomless field-grown plants, but not from symptomless plants derived from meristem-tip culture (mericlones). Healthy mericlones inoculated with F. lateritium isolated from chlorotic leaf distortion affected sweetpotato developed chlorotic leaf distortion symptoms after 3–7 wk in the greenhouse. Uninoculated control mericlones did not develop symptoms. Koch’s postulates were fulfilled, confirming F. lateritium as the causal agent of chlorotic leaf distortion in sweetpotato.