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POSTERS: Host resistance screening

Resistance of strawberry cultivars to crown rot caused by Phytophthora cactorum and P. nicotianae
Marcus Marin - Gulf Coast Research and Education Center, University of Florida. Natalia Peres- University of Florida - Gulf Coast Research and Education Center, Vance Whitaker- Gulf Coast Research and Education Center, University of Florida, Teresa Seijo- Gulf Coast Research and Education Center, University of Florida

Phytophthora crown rot is an important disease of strawberry worldwide. Phytophthora cactorum is the most common causal agent, however P. nicotianae was also recently reported causing crown rot in the U.S. Therefore, the goal of this study was to evaluate whether the resistance of strawberry cultivars from Florida and California differs between the two species causing Phytophthora crown rot. Sixteen strawberry cultivars were evaluated during two Florida strawberry seasons. Prior to planting, roots of each cultivar were submerged in a zoospore suspension (1x104 ml-1) for 5 min. The plants were then transplanted into previously fumigated beds. Plant wilting and mortality was assessed weekly, and AUDPC was calculated. Cultivars Sensation® Florida127, Winterstar, and Florida Radiance were highly susceptible, whereas Elyana, Camarosa, Fronteras, Sweet Charlie, and Strawberry Festival were highly resistant to both Phytophthora species. However’, ‘Florida Brilliance’ and ‘Cabrillo’ were both resistant to P. nicotianea yet susceptible to P. cactorum. Contrarily, ‘Florida Beauty’, ‘Ruby Gem’ and ‘Albion’ were susceptible to P. nicotianea and resistant to P. cactorum. These results emphasize the importance of screening for disease resistance to guide management recommendations in commercial strawberry production as well as the need for proper pathogen identification since cultivar susceptibility might differ.