By Matt Reese and Dale Minyo Corn harvest is wrapped up for Ohio, but challenges from vomitoxin in the 2020 crop have been lingering. The problem got its start with the fairly widespread development of Gibberella ear rot (GER) in corn around Ohio. Ohio State University Extension plant pathologist Pierce Paul said GER development is favored by warm, wet, or humid conditions between silk emergence (R1) and early grain development. “Unfortunately, slow dry-down coupled with delayed harvest, late-season rainfall, and/or high humidity, and warmer-than-usual late fall are responsible. Unlike the leaf diseases that you can see just by walking plots, ear diseases may go undetected, unless you peel back husks and check,” Paul said. “The fungus usually gets in during silking, then grows and produces vomitoxin as the grain develops. Weather conditions during grain-fill and that pre-harvest window determines how bad it gets. I have heard as much as 5 to 10 parts per million in the odd field, but levels between 2 and 5 ppm have been reported as well.”