Poster # 105
J.A. Cinderella1, K. Anderson2, G.C. Bergstrom3, W.W. Bockus2, C.A. Bradley4, M. Breunig5, E. Byamukama6 M.I. Chilvers5, C. Cowger7, T.R. Faske8, A.J. Friskop9, J. Kelly8, N.M. Kleczewski10, S. Mideros10, P.A. Paul11, T. Price12, N. Rawat13, J. Rupp2, S. Shim14, J. Stevens15, D. Telenko14, A.M. Koehler1
1. University of Delaware, Plant and Soil Sciences, Georgetown, Delaware
2. Kansas State University, Department of Plant Pathology, Manhattan, Kansas
3. Cornell, Plant Pathology and Plant Microbe Biology, Ithaca, New York
4. University of Kentucky, Department of Plant Pathology, Lexington, Kentucky
5. Michigan State University, Department on Plant, Soil and Microbial Sciences, East Lansing, Michigan
6. South Dakota State University, Department of Agronomy, Horticulture and Plant Science, Brookings, South Dakota
7. North Carolina State University, Department of Entomology and Plant Pathology, Raleigh, North Carolina
8. University of Arkansas, Department of Entomology and Plant Pathology, Fayetteville, Arkansas
9. North Dakota State University, Plant Pathology, Fargo, North Dakota
10. Growmark Inc., Agronomy Services Plant Pathology, Entomology Specialist, Technical Agronomist East and Southern Illinois, Illinois
11. Ohio State University, Department of Plant Pathology, Columbus, Ohio
12. Louisiana State University, Department of Plant Pathology and Crop Physiology, Winnsboro, Louisiana
13. University of Maryland, Plant Science & Landscape Architecture, College Park, Maryland
14. Purdue University, College of Agriculture, West Lafayette, Indiana
15. University of Nebraska-Lincoln, Department of Plant Pathology, Lincoln, Nebraska
Joseph Cinderella
University of Delaware
Fusarium head blight (FHB),
caused by the fungal pathogen Fusarium graminearum, is an important disease of small grains that can cause severe yield and quality reductions. In 2019, pydiflumetofen (Syngenta, Switzerland) was registered for use in the management of FHB in wheat, barley, rye, oats, and triticale. Pydiflumetofen is a new Succinate Dehydrogenase Inhibitor (SDHI) and an in vitro screening of 65 isolates was conducted to establish baseline sensitivities in F. graminearum isolated from wheat. Isolates were submitted from 16 states representing numerous small grain production regions of the United States. The
isolate set screened included 59 isolates collected in 2020-21 and 6 historic isolates collected from 1991-2013 that were never exposed to pydiflumetofen. The effective concentration to reduce mycelial growth by 50% (EC50) was determined for each isolate with a poison plate mycelial growth assay using fungicide-amended PDA plates at 0, 0.01, 0.05, 0.25, 1.0, and 5.0 μg/mL.
Mycelial growth EC50 values averaged by state for 2020-21 isolates ranged from 0.09 to 0.52 μg/mL. The average EC50 value of post 2019 isolates was 0.25 μg/mL and the historic isolates 0.21 μg/mL. This study demonstrates the inhibition of mycelial growth by this new chemistry in vitro and establishes preliminary baseline sensitivity values of F. graminearum isolates from 16 states across the US.
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