Verticillium wilt of tomato: I. Influence of inoculum potential of Verticillium dahliae on the behavior of tomato varieties Angela Hiper and Marmande VR

Abstract

The tomato varieties Angela Hiper (susceptible) and Marmande VR (race-1 Verticillium-resistant) showed different behavior, depending on inoculum concentration and on the isolate used. The higher the inoculum potential of T-1386 and T-1439 isolates, the greater both the development of the disease and the severity of the wilting symptoms. Very low severity levels of wilting and slow disease development were observed when race-1-resistant cultivar Marmande VR was inoculated with T-1335 isolate at the three desired concentrations (10⁴, 10⁵ and 10⁶ conídia/ml, and its reaction was then distin­guished from Angela Hiper one. A similar event occured when T-1289 andT-1335 isolates were inoculated on Marmande VR cultivar at 10⁶ and 10⁷ conidia/ml. Nevertheless, high severity levels of wilting symptoms were observed when T-1289 isolate was inoculated on Marmande VR at inoculum concentrations of 10⁸ conidia/ml, although that variety had behaved like the resistant one when inoculated with this isolate at lower concentrations. Inoculum at concentration of 10⁶ conidia/ml was the most proper one for identifying physiological races of V. dahliae through measurements of the reaction of Angela Hiper and Marmande VR tomato varieties under controlled conditions.