FUNGICIDE TIMING, RESISTANCE MONITORING, AND PHYTOPATHOMETRY FOR FIELD CROP DISEASES IN INDIANA

Protecting crops from disease requires continuous research because plant pathogen incidence, geographical range, and pathogenicity, are constantly shifting variables as agronomic practices and climate continue to evolve. The objectives of this research are to i.) evaluate field-scale fungicide timing programs for corn (Zea mays L.) diseases at multiple locations in Indiana; ii.) evaluate field-scale fungicide timing programs for soybean (Glycine Max (L.) Merr.) diseases at multiple locations in Indiana; iii.) continue to identify, document, and confirm the distribution of populations of the soybean frogeye leaf spot pathogen (Cercospora sojina) that contain the G143A mutation conferring resistance to quinone outside inhibitor (QoI) fungicides in Indiana; and iv.) assess the incidence, severity, and prevalence of tar spot (Phyllachora maydis) in Indiana. For the first and second objectives, field scale trials were established at three locations in Indiana from 2019 to 2022. No application timings at any location provided significant yield protection for corn or soybeans. To achieve the third objective, 165 isolates of C. Sojina were tested. In total, 24 out of the 32 counties sampled in 2021 and 2022 were documented with QoI-resistance. The fourth objective was accomplished by surveying Indiana counties for incidence and severity of tar spot. As of 2022, 86 out of 92 Indiana counties have been confirmed for the presence of tar spot.