Effects of Fungicides and Cultivar Resistance on Fusarium Head Blight and Deoxynivalenol in Spring Barley from 2014 to 2019

Abstract

Spring barley production and quality in the United States is severely impacted by Fusarium head blight (FHB), primarily caused by Fusarium graminearum. Management of FHB is best accomplished using an integrated approach including resistant varieties and fungicides. Field experiments were established from 2014 to 2019 to quantify the effects of host resistance, fungicide, and fungicide timing on management of FHB and deoxynivalenol (DON) and yield protection in spring barley. Three separate research objectives were investigated using multiyear and multilocation experiments. These included investigating the efficacy of prothioconazole + tebuconazole applied at either Feekes growth stage (FGS) 10.5 (full head) or 3 to 7 days after FGS 10.5; the efficacy of sequential fungicide applications occurring at both FGS 10.5 and 3 to 7 days after FGS 10.5 using prothioconazole + tebuconazole, metconazole, prothioconazole, or tebuconazole; and the efficacy and timing of pydiflumetofen + propiconazole. Pooled analysis results suggest that metconazole, prothioconazole + tebuconazole, and pydiflumetofen + propiconazole are all effective fungicides for reducing DON, reducing FHB, and protecting yield. The use of sequential fungicide applications with one occurring at FGS 10.5 and another at 3 to 7 days after FGS 10.5 provided greater suppression than a single application at FGS 10.5. The greatest DON reduction from pydiflumetofen + propiconazole occurred when applied at full head or 3 to 7 days after full head. Across all research objectives, the most effective single fungicide application timing to reduce FHB, reduce DON, and protect yield in barley is 3 to 7 days after FGS 10.5.