|JONES, LISA - New Zealand Institute Of Plant & Food Research|
|PSCHEIDT, JAY - Oregon State University|
Submitted to: International Congress of Plant Pathology Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/27/2018
Publication Date: 7/25/2018
Citation: Stockwell, V.O., Shaffer, B.T., Jones, L.A., Pscheidt, J.W. 2018. Fungicide resistance profiles of Botrytis cinerea isolated from berry crops in Oregon. Abstract for International Congress of Plant Pathology: Plant Health in A Global Economy; 2018 July 29-Aug 3; Boston, MA
Technical Abstract: The gray mold pathogen, Botrytis cinerea, causes pre- and post-harvest fruit rot and stem disease of berry crops. Disease control measures involve applications of fungicides in rotation or in combination from bloom to near harvest. B. cinerea can rapidly develop resistance to fungicides, which reduces control efficacy. Little was known about the fungicide resistance profiles of B. cinerea from berry crops grown in Oregon. We isolated B. cinerea from blackberry, blueberry, raspberry, and strawberry fruits in western Oregon fields from 2014 to 2017. Resistance to fungicides was determined by growth inhibition assays on fungicide-amended media. The media and discriminatory doses of formulated fungicides tested were: 1) potato dextrose agar amended with 0.5 ppm fenhexamid, 0.3 ppm fludioxonil, or 3 ppm iprodione, 2) yeast extract agar with 5 ppm boscalid, and 3) the defined medium, cyprodinil test agar (CTA), amended with 1 or 10 ppm cyprodinil. Among the 511 isolates evaluated, 61% were resistant to at least one fungicide. Boscalid resistance was common and resistance to fenhexamid or cyprodinil was frequently detected. Among the isolates with fungicide resistance, 64% were resistant to at least two fungicides and 36% were resistant to three or four of the fungicides. Although 39% of the isolates were sensitive to the fungicides tested, the emergence of multi-fungicide resistance may compromise the efficacy of chemical control of gray mold.