Comparative Response of Strawberries to Conidial Root-dip Inoculations and Infection by Soilborne Microsclerotia of Verticillium dahliae Kleb.

Abstract

Previous studies have demonstrated significant genetic variation for susceptibility to verticillium wilt, caused by Verticillium dahliae, among strawberry (Fragaria ×ananassa Duch.) genotypes adapted to California growing conditions. These evaluations have been conducted using a conidial root-dip inoculation procedure; valid application of this method in a breeding program assumes the reaction of inoculated plants will be predictive of their response to infection by more natural means. To test this expectation, we evaluated the responses of plants representing eight strawberry genotypes that were either root-dip inoculated prior to being transplanted into a fruit production field or were transplanted into soil artificially infested with pathogen propagules (microsclerotia). Both inoculation methods revealed significant variation among genotypes in all 3 years that tests were conducted and the absence of significant genotype × treatment interactions demonstrate similar rankings of genotypes with both methods. However, based on statistical repeatability, the root-dip inoculation method was more consistent over time (R = 0.759) than the soil inoculation method (R = 0.510).