Improving Fungicide Application Recommendations for Managing Fusarium Head Blight of Wheat

Fusarium head blight (FHB; a.k.a. “scab”) is the most important disease of wheat in Kentucky. The fungus that causes this disease (Fusarium graminearum) is always present every year, surviving mostly on corn residue. The greatest problem associated with FHB is the reduction in grain quality. The FHB fungus will produce a toxin known as deoxynivalenol (DON) that contaminates grain. When elevators detect grain with at least 2 ppm DON contamination, severe dockage can be applied (or in severe cases, outright rejection of grain may occur). Severely-infected grain may also be lighter in weight, causing low test weight, in which additional dockage can be applied at the elevator. For sustainable wheat production in Kentucky, it is important to continue to seek improved methods of managing FHB and DON. Although much research has been conducted with a focus of managing FHB in wheat with fungicides, many questions still remain. This proposal will build upon the results of projects funded previously, and results of this project will help improve fungicide application recommendations for management of FHB and DON in wheat. Specifically, the objectives are: 1. Evaluate different spray application technology configurations to develop recommendations for getting the best level of control of FHB and DON on wheat. 2. Evaluate different fungicide application timings and multiple fungicide application timings to wheat for control of FHB and DON. Objective 1 will focus on evaluating different nozzle tips and spray configurations (spray volume, pressure, speed, etc.) using a tractor-mounted sprayer. Over the past two seasons (2018 and 2019), Prosaro fungicide was used to help evaluate efficacy of different spray nozzle configurations. In the 2020 season, the best nozzle configurations observed previously will be optimized to help fine tune recommendations, and both Prosaro and Miravis Ace will be evaluated to ensure that these configurations are suitable for both fungicides. This is an important consideration as Miravis Ace contains a new active ingredient from the SDHI fungicide class, which differs from active ingredients in both Prosaro and Caramba, which are in in the triazole fungicide class only. The SDHI fungicides have different properties than triazole fungicides, which may affect their coverage on and systemicity within a wheat head. Data from the 2019 growing season are still being evaluated at the time that this was written; however, FHB severity appeared to be moderate to high in the trial, which should allow for significant differences among treatments to be detected. Objectives 2 will focus on different timings and multiple fungicide applications on wheat for FHB and DON control. With the recent EPA registration of the new product, Miravis Ace, it is important to evaluate this product over multiple growing seasons to better understand how it compares to other fungicides, in regards to its efficacy in managing FHB and on its effect on wheat yield and quality.