2025/10/24 by Mikaela Breunig, Adam M. Byrne, Janette L. Jacobs +3 · 1 voice
Agricultural and Biological Sciences · Biochemistry, Genetics and Molecular Biology · #Mycotoxins in Agriculture and Food #Plant Pathogens and Fungal Diseases #Plant and fungal interactions
paper · doi:10.1094/phyto-06-25-0214-r
openalex publication_date 2025/10/24 · openalex created_date 2025/10/25 · openalex updated_date 2026/07/27
Mycotoxin contamination of wheat and corn grain from Fusaria is a major agricultural concern. To characterize the population of Fusarium in Michigan, 569 isolates were collected, and species composition, TRI genotype, in vitro fungicide sensitivity, and fungicide field efficacy were determined. In wheat, the Fusarium sambucinum species complex comprised 90% of isolates, of which 82.5% of all isolates were F. graminearum. In corn, the F. sambucinum species complex comprised 40%, with 37% identified as F. graminearum, whereas species from the F. fujikuroi species complex comprised 50%. Within the F. fujikuroi complex, F. awaxy (4.6%) was found and had not previously been identified in the United States. Across F. graminearum isolates, TRI genotypes were found at the following percentages: 92% 15-acetyldeoxynivalenol (15-ADON), 6% 3-ADON, 1.6% NX-2, and no NIV. In vitro mycelial growth sensitivity assays to triazole fungicides demonstrated that Fusaria were more sensitive to metconazole than to tebuconazole or prothioconazole. Species-specific differences in sensitivity were identified across the fungicides tested, with F. tricinctum species complex members significantly less sensitive than F. graminearum isolates, and the F. fujikuroi species complex was significantly more sensitive. Within F. graminearum, 10 isolates had median effective concentration (EC 50 ) values 10-fold greater than sensitive isolates. A subset of these F. graminearum isolates were chosen to investigate if reduced sensitivity in vitro would lead to practical resistance in vivo. Field plots were inoculated with spore suspensions; however, no differences in the relative fungicide efficacy were found, signaling that no demethylation inhibitor fungicide resistance was identified in our collected isolates, despite differences in vitro. Although currently, there may not be practical resistance, monitoring should continue, as there is variation in in vitro sensitivities present within and among species.