Temperature Dependent Pathogenicity of Verticillium dahliae Kleb. Populations in Strawberry Plants of the Cultivar 'Elsanta'

In the most common strawberry cv. 'Elsanta', Verticillium infection can lead to rapid and strong wilt up to death of plants. 432 genotypes of Verticillium dahliae Kleb. from wilted and vital plants were isolated from 8 fields and typed by PCR-fingerprints. Under sterile conditions in a climate chamber, plants were inoculated with a single genotype, using 27 genotypes out of the 432. Wilt symptoms of these genotypes can be classified as avirulent, slightly virulent and virulent. At enhanced temperature of a second climate chamber, symptoms could be used to classify genotypes further as virulent under cold or warm conditions. Inoculation with a mixture of different climate-depending virulent genotypes resulted in vital plants with enhanced growth. From these data we conclude that the actual population in the plant is the main cause for wilt symptoms. Mixtures of different genotypes can be used to control wilt symptoms for different climate regions (WO 2007/051654).