FUSARIUM-WILT AND CROWN ROT OF SWEET BASIL - INVOLVEMENT OF SOILBORNEAND AIRBORNE INOCULUM

Fusarium oxysporum f. sp. basilici causes wilt and crown and root rot in sweet basil (Ocimum basilicum) in all basil-growing regions of Isra el. Wilting and death of basil plants were recorded, and isolates of F . oxysporum were obtained at high frequency from roots and all above-g round parts of diseased plants. Inoculation tests with representative isolates verified that the causal agent is F. oxysporum f. sp. basilic i. F. oxysporum f. sp. basilici causes both wilt and crown and root ro t. The following symptoms were observed: wilt of plants at all stages of growth, brown and black discoloration of roots and lower stems, con tinuous and discontinuous black lesions on stems, blackening and dryin g of vegetative apices, growth retardation, and xylem discoloration. T he stems were frequently covered with a pink-orange layer consisting m ainly of macroconidia, which could become airborne, as revealed by pro pagule trapping. Therefore, the pathogen has characteristics of both s oilborne and airborne pathogens. F. oxysporum f. sp. basilici was read ily recovered from structures inside the greenhouse, including concret e stumps, strings, pipes, and walls. Seeds collected from diseased pla nts were infested with the pathogen and produced diseased plants beari ng infested seeds. Because the pathogen is easily disseminated, a holi stic approach is necessary to control it. Because of the variety of sy mptoms associated with this disease, we suggest renaming it ''Fusarium wilt and crown rot.''