Impact of Foliar Fungicides on Gibberella Ear Rot and Deoxynivalenol Levels in Indiana Corn

Gibberella ear rot, caused by the fungus Fusarium graminearum (Schawbe), can cause significant yield reductions in corn (Zea mays L.) as well as reduce grain quality. Field experiments were conducted at two locations in Indiana to assess the impact of commercially available fungicides on Gibberella ear rot severity and deoxynivalenol (DON) accumulation in hybrid corn grain. The experiments were arranged in a random complete block design with both inoculated and noninoculated treatments. Three fungicides—azoxystrobin + propiconazole, prothioconazole, and pyraclostrobin—were applied during silking (R1), and Gibberella ear rot severity, DON accumulation in grain, and corn yield were measured. Inoculated treatments had higher disease severity and DON and lower yield (P < 0.001) compared with noninoculated treatments. Fungicides reduced Gibberella ear rot severity in two location-years, but did not reduce DON in those experiments. All other fungicide treatments in all locations and years did not reduce disease severity or DON when compared with treatments not sprayed with fungicide. No fungicide increased DON levels in grain in any location or year. These results indicate that fungicide applications during the silking stage of corn may not consistently reduce DON levels in hybrid corn.