Authors: Raissa Debacker Moura 1, Claudio Dias da Silva Jr 1, Angel De Trinidad 1, Erick DeWolf 1, Rodrigo B. Onofre 1, Jessica Rupp Noller 1, Tim Todd 1, and Kelsey Andersen Onofre 1
1. Kansas State University, Department of Plant Pathology, Manhattan, Kansas.
Corresponding Author: Kelsey Andersen Onofre, andersenk@ksu.edu.
Presenting Author: Raissa Debacker Moura
Abstract
Fusarium head blight (FHB), caused by Fusarium graminearium, is a globally important wheat disease. A single fungicide application at early flowering (Feekes 10.5.1) is generally recommended when conditions favor disease development. We hypothesize that FHB control can be improved by making a single application at Feekes 10.5.1 followed by a second application 4 days later. Field experiments evaluating the efficacy of dual applications were conducted over three winter wheat seasons across two locations per season. The FHB susceptible variety ‘KanMark’ was used during 2021-2022 season, and the variety ‘Green Hammer’ was used during 2022-2023 and 2023-2024 seasons. Four F. graminearum isolates collected from Kansas were used to produce infested corn spawn inoculum. Plots were inoculated and received supplemental sprinkler irrigation. Treatments, which were consistent with the USWBSI MGMT-CP uniform fungicide trial (UFT) protocol, consisted of 1) untreated control, 2) Prosaro® 6.5 fl oz/A at flowering; 3) Miravis® Ace 13.7 fl oz/A at flowering; 4) Prosaro Pro 10.3 fl oz/A at flowering; 5) Sphaerex® 7.3 fl oz/A at flowering, 6) Miravis Ace 13.7 fl oz/A followed by Prosaro Pro 10.3 fl oz/A; 7) Miravis Ace 13.7 fl oz/A followed by Sphaerex 7.3 fl oz/A; and 8) Miravis Ace 13.7 fl oz/A followed by TebuStar 4 fl oz/A. Response variables were subjected to mixed model ANOVA and means were compared using Tukey’s HSD test. Additionally, the influence of disease level on treatment responses was modeled by including FHB index as a continuous covariate in a mixed model ANOVA for yield and DON. All fungicide treatments reduced FHB index and DON relative to the untreated control. Treatments including one Miravis Ace application had the lowest disease and DON levels with FHB index values between 7-12% and DON concentrations between 9-12 ppm. In comparison, the other fungicide treatments had FHB index values between 16-18% and DON levels ranging from 14-16 ppm. These differences in disease control also influenced grain yields with treatments including Miravis Ace yielding between 62-65 bu/A and the other fungicide treatments yielding 52-56 bu/A. The covariate analysis with FHB index demonstrated that the efficacy of Miravis Ace was more pronounced at high levels of disease. Overall, the application of Miravis Ace alone or in combination with a second fungicide applied 4 days after Feekes 10.5.1 provided enhanced FHB control, particularly under high disease pressure.