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Etiology

Fusarium Wilt and Crown Rot of Sweet Basil: Involvement of Soilborne and Airborne Inoculum. A. Gamliel, Institute of Agricultural Engineering and Department of Plant Pathology, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel; Talma Katan(2), H. Yunis(3), and J. Katan(4). (2)Institute of Agricultural Engineering and Department of Plant Pathology, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel; (3)Ministry of Agriculture, Extension Service, Tel Aviv, Israel; (4)Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot 76100, Israel. Phytopathology 86:56-62. Accepted for publication 21 August 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/Phyto-86-56.

Fusarium oxysporum f. sp. basilici causes wilt and crown and root rot in sweet basil (Ocimum basilicum) in all basil-growing regions of Israel. Wilting and death of basil plants were recorded, and isolates of F. oxysporum were obtained at high frequency from roots and all aboveground parts of diseased plants. Inoculation tests with representative isolates verified that the causal agent is F. oxysporum f. sp. basilici. F. oxysporum f. sp. basilici causes both wilt and crown and root rot. The following symptoms were observed: wilt of plants at all stages of growth, brown and black discoloration of roots and lower stems, continuous and discontinuous black lesions on stems, blackening and drying of vegetative apices, growth retardation, and xylem discoloration. The stems were frequently covered with a pink-orange layer consisting mainly of macroconidia, which could become airborne, as revealed by propagule trapping. Therefore, the pathogen has characteristics of both soilborne and airborne pathogens. F. oxysporum f. sp. basilici was readily recovered from structures inside the greenhouse, including concrete stumps, strings, pipes, and walls. Seeds collected from diseased plants were infested with the pathogen and produced diseased plants bearing infested seeds. Because the pathogen is easily disseminated, a holistic approach is necessary to control it. Because of the variety of symptoms associated with this disease, we suggest renaming it "Fusarium wilt and crown rot."