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POSTERS: Chemical control

Effects of two-treatment fungicide programs on grain yield and quality of Fusarium head blight-affected Wheat
Jorge David Salgado - The Ohio State University. Carl Bradley- University of Kentucky, Ruth Dill-Macky- University of Minnesota, Madeleine Smith- University of Minnesota, Alyssa Collins- Southeast Agricultural Research & Extension Center, Laurence Madden- The Ohio State University, Dalitso Yabwalo- Sout

The combination of a single anthesis application of a triazole fungicide (prothioconazole [PROT], metconazole [METC], tebuconazole [TEBU], or PROT+TEBU) with a moderately resistant (MR) cultivar has been shown to be more efficacious than fungicide or resistance alone for managing Fusarium head blight (FHB) and deoxynivalenol (DON). However, this approach is often not effective enough to prevent grain yield and quality losses when conditions favor FHB and DON. Data were collected from 54 field experiments across 16 states to evaluate the benefits of two-treatment programs (T2; METC or PROT at anthesis followed by TEBU 4-6 days later and PROT+TEBU at anthesis followed by METC 4-6 days after) for FHB management in cultivars with different levels of resistance. Anthesis applications of PROT+TEBU (T1) and non-treated checks were included as references. For each resistance x fungicide program combination, percent reduction of Fusarium damaged kernels (FDK) and DON, and increases in yield (YLD) and test weight (TW) were estimated relative to the susceptible non-treated check. Price discounts based on grain quality were also estimated for each management combination. Combining T2 with a moderately susceptible (MS) or MR cultivar reduced FDK and DON by up to 80% and increased YLD and TW by up to 1.6 MT/ha and 59 kg/m3, respectively. Depending on the level of FHB, T2 was more effective than T1 on MS compared to MR cultivars. However, total price discounts were consistently lower when T2 was combined with an MR cultivar ($4-9/MT) than with an MS ($5-14/MT) or S ($7-40/MT) cultivar.