PHYSIOLOGICAL RACES AND VEGETATIVE COMPATIBILITY GROUPS OF FUSARIUM-OXYSPORUM F SP MELONIS IN ISRAEL

Two vegetative compatibility groups (VCGs) and four physiologic races (0, 1, 2, and 1-2) were identified among 122 isolates of Fusarium oxysporum f. sp. melonis in Israel, One VCG corresponded to the previously described VCG0135, whereas the other, VCG0138, is new and was divided into two subgroups. VCG0135 contained isolates of races 0 and 2, and VCG0138 contained isolates of races 0, 1, and 1-2. In one region with a long history of cucurbit cropping, all races and VCGs were found within 17 km of each other, suggesting a high diversity of the pathogen within a relatively small area. Based on vegetative compatibility, it is suggested that in Israel race 2 could have evolved from race 0 of VCG0135, and races 1 and 1-2 from race 0 of VCG0138.