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POSTERS: Chemical control

Analysis of fungicide efficacy on Macrophomina phaseolina isolates from West Tennessee
Rachel Guyer - University of Tennessee. Kate Armstrong- University of Tennessee at Martin, Heather Kelly- University of Tennessee

Macrophomina phaseolina, causal agent of charcoal rot in soybean (Glycine max) and corn (Zea mays), is a prevalent soilborne fungal pathogen occurring across the United States and is most common in the southern and midwestern states. The fungus produces overwintering structures, microsclerotia, that allow it to persist in debris and soil, making no-till fields particularly at risk of harboring inoculum across growing seasons and susceptible crops. Isolates of M. phaseolina were collected from soil and soybean root debris samples submitted by farmers in West Tennessee across the 2017-2018 growing seasons. A subset of these isolates were screened for fungicide sensitivity to one or more active ingredients in the following fungicide classes: demethylation inhibitor (DMI), methyl benzimidazole carbamate (MBC), quinone outside inhibitor (QoI), and succinate dehydrogenase inhibitor (SDHI). Colony radial growth was also observed for virulence analysis. Fungicide screening results, colonial growth analyses, and overall distribution and abundance across sampled areas will be presented.