Korolev, N., Department of Plant Pathology, ARO, Volcani Center, Bet Dagan 50250, Israel
Pérez-Artés, E., Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible (IAS), Consejo Superior de Investigaciones Científicas (CSIC), Apartado 4084, 14080 Córdoba, Spain
Bejarano-Alcázar, J., Departamento de Protección Vegetal, Centro de Investigación y Formación Agraria, Junta de Andalucía, Apartado 3092, 14080 Córdoba, Spain
Rodríguez-Jurado, D., Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible (IAS), Consejo Superior de Investigaciones Científicas (CSIC), Apartado 4084, 14080 Córdoba, Spain
Katan, J., Department of Plant Pathology and Microbiology, Hebrew University, Rehovot 76100, Israel
Katan, T., Department of Plant Pathology, ARO, Volcani Center, Bet Dagan 50250, Israel
Jiménez-Díaz, R.M., Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible (IAS), Consejo Superior de Investigaciones Científicas (CSIC), Apartado 4084, 14080 Córdoba, Spain, Departamento de Agronomía, Universidad de Córdoba, Apartado 3048, 14080 Córdoba, Spain, Departamento de Protección de Cultivos, IAS-CSIC, Apartado 4084, 14080 Córdoba, Spain

Genetic diversity and phenotypic diversity in Verticillium dahliae populations on cotton were studied among 62 isolates from Spain and 49 isolates from Israel, using vegetative compatibility grouping (VCG), virulence and molecular assays. In Spain, defoliating V dahliae isolates (D pathotype) belong to VCG1, and non-defoliating isolates (ND) belong to VCG2A (often associated with tomato) and VCG4B (often associated with potato). The D pathotype was not identified in Israel. The ND pathotype in Israel is comprised of VCG2B and VCG4B. Isolates in VCG2B and VCG4B ranged in virulence from weakly virulent to highly virulent. The highly virulent isolates induced either partial defoliation or no defoliation. Virulence characteristics varied with inoculation method and cotton cultivar. Highly virulent isolates from Israel were as virulent as Disolates from Spain under conditions conducive to severe disease. The D pathotype is pathologically and genetically homogeneous, whereas the ND pathotype is heterogeneous with respect to virulence, VCG, and molecular markers based on single-primer RAPD and on PCR primer pairs.