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Poster: Biology & Disease Mgmt: Chemical Control


Characterization of fungicide resistance phenotypes in Botrytis cinerea populations from blueberry in Florida
A. AMIRI (1), A. Zuniga (2), P. Harmon (2), N. Peres (2) (1) Washinton State University, U.S.A.; (2) University of Florida, U.S.A.; (3) University of Florida, U.S.A.; (4) University of Florida, U.S.A.

Botrytis blossom blight caused by Botrytis cinerea is an important blueberry disease and is mainly controlled by fungicide applications prior and during bloom. In this study, we evaluated the sensitivity of 624 B. cinerea isolates collected from 11 blueberry fields in central Florida between February and May of 2013, 2014, and 2015. Six fields were near strawberry and 5 fields were located 40 km or more from strawberry fields. Isolates were grown on malt yeast extract agar and tested for their sensitivity to pyraclostrobin (Pyra), boscalid (Bosc), penthiopyrad (Penth), fludioxonil (Flud), fenhexamid (Fenh), cyprodinil (Cyp), and iprodione (Ipr) using a spore germination inhibition assay and previously determined discriminatory doses. Overall, disease incidence was higher in samples collected from blueberry fields planted next to strawberry fields compared to blueberry fields alone. In 2013, resistance frequencies were 1.7, 14.9, 46.3, 49.5, 57.8, 57.9 and 92.6% for Flud, Penth, Ipr, Cyp, Bosc, Fenh, and Pyra, respectively. Similar resistance frequencies were observed in 2014 and 2015 with some significant differences across locations and fungicides. Resistance frequencies were higher in blueberry fields next to strawberry fields for all fungicides except Flud, Penth and Ipr. Our findings indicate that resistance to multiple fungicides in B. cinerea is widespread in blueberry fields and that resistant populations selected on strawberry may spread to adjacent crops.