Research
Sensitivity of the Causal Agent of Northern Leaf Blight of Corn, Exserohilum turcicum, to the Demethylase-Inhibiting Fungicide Flutriafol
AffiliationsAuthors and Affiliations
- Nolan R. Anderson1
- Austin G. McCoy2
- Cristina Castellano1
- Martin I. Chilvers2
- Eric Alinger3
- Tom W. Allen4
- Kaitlyn Bissonnette5
- Drake Copeland6
- Nick Hustedde6
- Tamra A. Jackson-Ziems7
- Nathan Kleczewski8
- Christopher Leon6
- John Mueller9
- Paul Price III10
- Richard Raid11
- Alison E. Robertson12
- Edward J. Sikora13
- Darcy E. P. Telenko14
- Matthew Wiggins6
- Kiersten A. Wise1 †
- 1Department of Plant Pathology, University of Kentucky Research & Education Center, Princeton, KY
- 2Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI
- 3Corteva Agriscience, Marion, IL
- 4Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Delta Research and Extension Center, Mississippi State University, Stoneville, MS
- 5Division of Plant Science and Technology, University of Missouri, Columbia, MO
- 6FMC Corporation, Philadelphia, PA
- 7Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE
- 8Growmark Inc., Bloomington, IL
- 9Department of Plant and Environmental Sciences, Clemson, SC
- 10LSU AgCenter, Macon Ridge Research Station, Winnsboro, LA
- 11Department of Plant Pathology, Everglades Research and Education Center, Belle Glade, FL
- 12Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA
- 13Department of Entomology and Plant Pathology, Auburn University, Auburn, AL
- 14Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN
Published Online:31 May 2024https://doi.org/10.1094/PHP-11-23-0098-RS
Abstract
Fungicides including active ingredients in the demethylation inhibitor group (Fungicide Resistance Action Committee Group 3) are used to manage corn diseases such as northern corn leaf blight, caused by Exserohilum turcicum. This study assessed the level of sensitivity to the demethylation-inhibiting fungicide flutriafol on a population of 81 E. turcicum isolates collected from across the United States in 2020. Sensitivity to flutriafol for E. turcicum was assessed using fungicide-amended media to determine the effective concentration needed to limit hyphal growth by 50%. The mean absolute EC50 values of the overall population calculated using the four-parameter log-logistic and Weibull2 four-parameter models were 2.1881 and 3.2643 µg/ml, respectively. The growth of most isolates (n = 70, 86.4%) was completely inhibited by 1 µg/ml of flutriafol. However, the growth of seven isolates (8.6%) was only completely inhibited at 10 or 100 µg/ml, and complete inhibition was not observed at 100 µg/ml for four isolates (4.9%). These results suggest that there may be isolates of E. turcicum in the United States that are resistant to flutriafol. Additional fungicide sensitivity screening is critical to monitor the development of fungicide resistance in U.S. populations of E. turcicum.
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