Tsror, L.L., Gilat Experiment Station, Agricultural Research Organization, Mobile Post Negev, 85280, Israel
Nachmias, A., Gilat Experiment Station, Agricultural Research Organization, Mobile Post Negev, 85280, Israel
Livescu, L., Gilat Experiment Station, Agricultural Research Organization, Mobile Post Negev, 85280, Israel
Perombelon, M.C.M., Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, United Kingdom
Barak, Z., Biology Department, Ben-Gurion University, Beer-Sheva, Israel

The interaction between Erwinia carotovora subsp. atroseptica (Eca) and Verticillium dahliae and its effect on symptom development in potato cultivars showing different degrees of resistance to them was examined over two seasons in irrigated fields in a hot, dry climate. Four cultivars were used: Cara, highly resistant to blackleg and tolerant to Verticillium wilt; Pentland Crown also resistant to blackleg but susceptible to Verticillium wilt; Désirée, moderately susceptible to blackleg but tolerant to Verticillium wilt; and Maris Bard, susceptible to both diseases. Seed tubers were inoculated with Eca immediately after harvest in Scotland, to simulate natural infection, and then planted in Israel in soil naturally infested by V. dahliae. In Verticillium tolerant cultivars, Eca infection increased the rate of colonization by V. dahliae and significantly enhanced symptom development, as assessed by suppression of plant height and wilt symptoms. © 1990 Kluwer Academic Publishers.