Lahkim, L.T., Agricultural Research Organization, Gilat Experiment Station, Negev, 85280, Israel
Nachmias, A., Agricultural Research Organization, Gilat Experiment Station, Negev, 85280, Israel

Reciprocal (susceptible/resistant) grafting experiments were used to determine whether the root is the major site of resistance to Verticillium wilt disease in tomato and tolerance in potato. Increased resistance/tolerance was seen in both species when the resistant cultivar served as rootstock. In potato, however, stem-dipping experiments indicated that tolerance was independent of the root. In experiments designed to determine whether a major gene plays a role in Verticillium wilt tolerance in potato, tomato races 1 and 2 of V. dahliae did not show differential pathogenicity on tolerant potato cultivars inoculated by the root-dip method. The results indicate that the root system plays an important role in the defense mechanisms to Verticillium wilt both in tomato and potato. © 1995 Taylor & Francis Group, LLC.