Vegetative compatibility of Fusarium oxysporum from sweet basil in Israel

Fusarium wilt and crown rot of sweet basil, caused by Fusarium oxysporum f.sp. basilici (F.o.ba.), is widespread in Israel. Affected plants show a variety of symptoms, including vascular wilt as well as crown rot, and masses of macroconidia on stem surfaces. We used vegetative compatibility to determine whether F.o.ba. isolates associated with various symptoms and sources are genetically related. All 119 isolates previously described as F.o.ba., and 42 additional F. oxysporum isolates which had not been tested for pathogenicity, belonged to a single vegetative compatibility group (VCG). The various symptoms are therefore induced by a single pathogenic form which appears to be a specific clone of F. oxysporum. The isolates of F.o.ba. from Israel were vegetatively compatible with eight isolates of F.o.ba. from Italy and the USA, but not with nonpathogenic isolates of F. oxysporum from basil, or with F.o. lycopersici or F.o. radicis-Iycopersici from tomato. We conclude that the population of F.o.ba in Israel belongs to the common VCG of this pathogen described in the USA, and which includes American and Italian isolates.