Identification of Cauliflower Cultivars that Differ in Susceptibility to Verticillium longisporum using Different Inoculation Methods

The response of 13 European cauliflower cultivars to Verticillium longisporum was evaluated using two greenhouse tests and one in vitro inoculation test. The greenhouse tests involved dipping roots of 3-week-old seedlings in a conidial suspension or inoculating the soil of 3-week-old seedlings with Verticillium microsclerotia. The in vitro test involved the inoculation of 9-day-old seedlings with Verticillium conidia. Useful disease parameters were the area under disease progress curve and plant growth reduction for the greenhouse tests and fresh weight reduction for the in vitro test. Significant correlations were found among the three inoculation methods. Irrespective of the inoculation method used, cultivar Sernio was most resistant to V. longisporum, while Minaret was the most susceptible cultivar. The pathogen could be re-isolated from the hypocotyls and from the stem of Minaret 4 and 49 days after inoculation respectively, whereas V. longisporum could never be re-isolated from Sernio . These results suggest that the more resistant cauliflower cultivar Sernio can suppress the ascent and the proliferation of V. longisporum into the plant