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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 #413196
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: Phenotypic and molecular characterization of Botrytis cinerea from blueberry fields in the Pacific Northwest for tolerance of SDHI fungicides

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

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/9/2024
Publication Date: 3/28/2024
Citation: Baral, R., DeLong, J.A., Stockwell, V.O., Mattupalli, C. 2024. Phenotypic and molecular characterization of Botrytis cinerea from blueberry fields in the Pacific Northwest for tolerance of SDHI fungicides [abstract]. American Phytopathological Society Annual Meeting.

Interpretive Summary:

Technical Abstract: Botrytis cinerea is the causal agent of gray mold of blueberry. This disease is difficult to manage due to the propensity of the pathogen to develop tolerance to various fungicides. Succinate dehydrogenase inhibitor (SDHI) fungicides are effective botrycides, but SDHIs were rated medium to high resistance risk for Botrytis by the Fungicide Resistance Action Committee. In this study, 375 B. cinerea isolates from 35 blueberry fields in the Pacific Northwest in 2022 were characterized with spore germination assays for their sensitivity to the SDHIs, boscalid and fluxapyroxad each at 10 ppm, and fluopyram and isofetamid each at 5 ppm. A subset of 125 B. cinerea isolates were grouped by four SDHI tolerance patterns: I. Boscalid only (n=37); II. Boscalid and fluxapyroxad (n=5); III. Boscalid, fluopyram, and fluxapyroxad (n=38); IV. All four fungicides (n=45). Analysis of sdhB sequences from these isolates revealed five known mutations, including H272R, H272Y, H272V, P225F, and N230I, at frequencies of 29.6, 4.0, 6.4, 29.6, and 30.4%, respectively. Isolates of group I, II, and III had H272R, H272Y, and N230I mutations, respectively, while group IV had either H272V or P225F mutation. The P225F, H272V, and N230I mutations in sdhB confer cross-resistance to multiple SDHI fungicides and emphasizes the need for careful use and rotation of fungicides to effectively manage B. cinerea in blueberry fields in the Pacific Northwest.