Disease Note.

Stem Rot of Basil Caused by Sclerotinia sclerotiorum. . G. E. Holcomb, Department, and Burden Research Plantation, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803. M. J. Reed, Plant Pathology and Crop Physiology Department, and Burden Research Plantation, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803. Plant Dis. 78:09241. Accepted for publication 19 May 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0924E.

Symptoms of wilt and stem necrosis, sometimes accompanied by white, cottony mycelia, were observed on 80% of 200 basil plants (Ocimum basilicum L.) growing in a plastic-covered greenhouse in Baton Rouge, Louisiana. The fungus was isolated on 2% water agar, and produced white mycelia and black sclerotia on potato-dextrose agar (PDA). Sclerotia-producing cultures of the fungus were identified as Sclerotinia sclerotiorum (Lib.) de Bary based on taxonomic characteristics of the plant pathogenic species of Sclerotinia (1). Koch’s postulates were fulfilled by inoculating nonwounded stems of twelve 10-cm-tall basil plants (1.5 mo old) with mycelial plugs from 7-day-old cultures of S. sclerotiorum. All inoculated plants developed symptoms of wilt and stem necrosis, and the pathogen was reisolated from five. A similar disease caused by S. sclerotiorum was reported on basil from the island of Sardinia in 1963 (2). This is the first report of 5. sclerotiorum on basil in the United States.