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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Disease and Pest Management Research Unit » Research » Publications at this Location » Publication #413198
Research Project: Knowledge Based Tools for Exotic and Emerging Diseases of Small Fruit and Nursery Crops

Location: Horticultural Crops Disease and Pest Management Research Unit

Title: Characterization of Botrytis spp. on red raspberries in Northwestern Washington

Author
item Delong, Jeffery - Jeff
item MATTUPALLI, CHAKRADHAR - Washington State University Extension Service
item Stockwell, Virginia

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/9/2024
Publication Date: 3/28/2024
Citation: DeLong, J.A., Mattupalli, C., Stockwell, V.O. 2024. Characterization of Botrytis spp. on red raspberries in Northwestern Washington [abstract]. American Phytopathological Society Annual Meeting.

Interpretive Summary:

Technical Abstract: Botrytis spp. causes gray mold, a disease that results in significant yield losses of red raspberries in the field and during postharvest. Management of this disease in northwestern Washington (NW) relies on applications of several site-specific fungicides throughout the growing season. However, Botrytis spp. is at high risk for development of fungicide resistance due to its genetic diversity and high fecundity. In this study, 1,176 Botrytis spp. isolates were collected from 12 red raspberry fields in NW during March, May, and July of each 2022 and 2023 growing season. A subset of 432 isolates were screened for sensitivity to fungicides in the Fungicide Resistance Action Committee (FRAC) group 7 (boscalid and fluxapyroxad at 10 ppm; fluopyram, and isofetamid at 5 ppm) using spore germination assays. Incidence of Botrytis isolates with fungicide tolerance, were detected in each field and increased across both years. Notably, a higher incidence (0.25 – 0.62) of isolates exhibited reduced sensitivity to fluopyram and fluxapyroxad compared to the other fungicides. To detect sdhB mutations associated with reduced sensitivity, a subset of 28 isolates were sequenced. Genotype mutations H272R, P225F, and N230I with frequencies 0.11, 0.43 and 0.25 respectively, were observed with varying patterns of cross-resistance among all FRAC 7 fungicides. Confirmation of sdhB mutations demonstrate the need for fungicide rotation and re-evaluation of application timings for management.