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POSTERS: Host resistance screening

Resistance to anthracnose in 76 cultivars and elite breeding lines of strawberry
Omar Gonzalez Benitez - California Polytechnic State University. Shashika Hewavitharana- California Polytechnic University San Luis Obispo, Gerald Holmes- Strawberry Center, California Polytechnic State University

Anthracnose, caused by Colletotrichum acutatum is an economically important disease of strawberry (Fragaria × ananassa). All parts of the plant are susceptible, resulting in fruit rot as well as plant mortality. Host plant resistance to anthracnose exists but could be better utilized if susceptibility of strawberry genotypes was widely known. In this experiment we evaluated the susceptibility of 76 genotypes to anthracnose during the 2018-19 season in San Luis Obispo, CA. Strawberry genotypes were selected from six breeding programs: University of California Davis, University of Florida, Driscoll’s, Plant Sciences, Planasa and Lassen Canyon. Bare-root transplants of each genotype were placed in a 1-gal plastic bag, mixed with 100 ml of inoculum (1×106 spores/ml) and shaken for one minute immediately prior to planting (10 plants per rep; 4 reps per genotype) in the field. A non-inoculated control was included for each genotype. Weekly plant mortality assessments started three weeks after planting, when plants began to show symptoms and signs of infection. The causal agent was confirmed as C. acutatum using standard plating techniques. At 4.5 months after planting, susceptibility of all genotypes ranged from 0 to 100% mortality with the average across all genotypes at 45.0%; 23 genotypes had >70% mortality while 27 genotypes had <25% mortality.