Improving Fungicide Application Recommendations for Managing Fusarium Head Blight of Wheat and Barley

Fusarium head blight (FHB; a.k.a. “scab”) is the most important disease of wheat and barley in Kentucky. The fungus that causes this disease (Fusarium graminearum) is always present every year, surviving on corn residue and residue from small grain crops. Although yield losses associated with FHB can be a problem, the greatest problem associated with FHB is the reduction in grain quality. The FHB fungus, F. graminearum, will produce a toxin known as deoxynivalenol (DON; a.k.a. “vomitoxin”) 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. Although much research has been conducted with a focus of managing FHB in wheat and barley with fungicides, many questions still remain. This proposal will repeat the objectives of the proposal funded for the 2018 season. If successfully completed, the results of this project will help improve fungicide application recommendations for management of FHB and DON in wheat and barley. 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. 3. Evaluate different fungicide application timings and multiple fungicide application timings to barley 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. In the 2018 season, multiple nozzle configurations and sprayer speeds were evaluated. Simulated wheat heads with water-sensitive spray cards were used to evaluate spray coverage and droplet size. In addition, FHB severity was evaluated and grain samples were collected for DON contamination levels. These data are currently being analyzed. The best treatments in 2018 will be configured for optimization and evaluated in 2019. Objectives 2 and 3 will focus on different timings and multiple fungicide applications on wheat and barley for FHB and DON control. The 2018 season was the first in which Miravis Ace, a new product from Syngenta) was evaluated in these trials. Repeating these trials in 2019 will allow for evaluation of this new product across multiple years.