Abdulkadir I. Dalha (he/him/his)
Post Doctoral Researcher
Department of Plant Pathology & Crop Physiology, Louisiana State University
Baton Rouge, Louisiana, United States
Shubham Kumar Jaiswal
Student Intern
LSU AgCenter
Baton Rouge, Louisiana, United States
Jonathan Patrick Amie
LSU
Baton Rouge, Louisiana, United States
Stephanie Ramos
Department of Plant Pathology & Crop Physiology, Louisiana State University
Baton Rouge, Louisiana, United States
Beatriz M. Carvalho
Postdoctoral Researcher
Department of Plant Pathology & Crop Physiology, Louisiana State University
Baton Rouge, LA, USA
Ernesto Da Silva
LSU
Baton Rouge, Louisiana, United States
Pedro Henrique Dias dos Santos
Postdoctoral Researcher
Department of Plant Pathology & Crop Physiology, Louisiana State University
Baton Rouge, Louisiana, United States
Jonathan K. Richards
Associate Professor
Department of Plant Pathology & Crop Physiology, Louisiana State University, Baton Rouge, LA 70803
Baton Rouge, Louisiana, United States
David Moseley
Assistant Professor/Soybean Specialist
Dean Lee Research & Extension Center, Louisiana State University
Alexandria, Louisiana, United States
Trey Price, n/a
Associate Professor
Macon Ridge Research Station, Louisiana State University, Winnsboro, LA 71295
Winnsboro, Louisiana, United States
Boyd Padgett
Professor
Dean Lee Research & Extension Center, Louisiana State University
Alexandria, Louisiana, United States
Tom W. Allen
Extension/Research Professor
Delta Research & Extension Center, Mississippi State University
Stoneville, Mississippi, United States
Terry Spurlock, PhD
Associate Professor
Department of Entomology and Plant Pathology. University of Arkansas System Division of Agriculture
Little Rock, Arkansas, United States
Vinson P. Doyle
Associate Professor
Department of Plant Pathology & Crop Physiology, Louisiana State University, Baton Rouge, LA 70803
Baton Rouge, Louisiana, United States
Sara Thomas-Sharma
Assistant Professor
Department of Plant Pathology & Crop Physiology, Louisiana State University
Baton Rouge, Louisiana, United States
Cercospora leaf blight (CLB), caused predominantly by Cercospora cf. flagellaris among other species of Cercospora, is a major soybean disease in parts of the midsouthern U.S. (Arkansas, Louisiana, and Mississippi). Between 2013 and 2023 surveys estimate between $46 and $166 million losses attributed to CLB. CLB management relies heavily on fungicides applied at specific soybean growth stages, and currently, the most frequently suggested products include a combination of demethylation inhibitors (DMIs), quinone outside inhibitors (QoIs), and succinate dehydrogenase inhibitors (SDHIs). The CLB pathogen population has developed resistance to QoIs and is insensitive to SDHIs. Therefore, it is important to assess resistance to the DMIs, as it may represent the only remaining effective class. Forty-nine C. flagellaris isolates collected between 2019 and 2020 were screened using poison plate assays. Three active ingredients (flutriafol, propiconazole, and tetraconazole) were tested at six concentrations (0, 0.01, 0.1, 1, 10, and 100 ppm) each. The range of EC50 was 0.007 to 18.2 µg/ml, 0.004 to 0.714 µg/ml, and 0.009 to 2.769 µg/ml, for flutriafol, propiconazole, and tetraconazole, respectively. High-throughput microtiter assays that rapidly detect resistance are also being developed to use on additional isolates. The results from this research aim to guide soybean farmers by identifying fungicide products that remain efficacious in their ability to manage C. flagellaris, and ultimately minimize economic losses to CLB across the midsouthern U.S.