Abnormal corn ears may look like a cosmetic problem, but depending on the severity, they can deliver a significant hit to yield, reports Osler Ortez, Ohio State University corn specialist.
“If a field is managed for 200-bushel corn but only delivers 100 bushels because abnormal ears dominate, then every pound of nitrogen, every inch of irrigation and every pass you make across that field becomes much harder to justify,” he says.
Yield losses from abnormal corn ears can range from 35% to 91% in affected plants, with typical field-wide impacts often trailing lower, Ortez reports.
For reference, an “average” corn ear generally produces 16 kernel rows with about 800 kernels per ear, according to the Iowa State Extension.
Irregularities such as zipper ears (shown below), earless plants or multiple ears, reduce grain yield through poor kernel set, abortion or reduced kernel weight.
Ortez emphasizes no single factor explains abnormal ear development. It’s nearly always the result of an interaction between three factors that corn researchers refer to as GEM:
G — Genetics (hybrid)
E — Environment (weather, stress)
M — Management (practices)
He adds that understanding when the stress is happening, the timing of it, is also important. For instance, early-season stress can limit ear initiation and potential ear number, while midseason issues impact pollination and kernel set. Late-season stress reduces kernel fill and overall weight.
Strategic Management Levers
While the weather can’t be controlled, Ortez says understanding the GEM interaction gives corn growers more leverage than they realize.
He lists three management decisions that can help growers mitigate the risk of abnormal ear development:
1. Evaluate the genetics: Treating hybrid selection as a defensive tool against ear problems — right alongside disease tolerance and standability — is one of the clearest ways to lower risk.
2. Pick a recommended seeding rate: In Nebraska field trials, Ortez observed abnormal ears increased at both ends of the seeding rate spectrum.
“Chasing a few extra bushels with aggressive populations, especially on drought-prone or otherwise stressed acres, often backfired when stress hit at the wrong time,” he notes. Conversely, pulling populations too low also created conditions where ear development went off track.
3. Consider the planting date: Researchers found planting hybrids outside the optimal window — either very early into cold, wet conditions or very late into heat and moisture stress — made it more likely sensitive growth stages would line up with damaging stress. Matching planting date to local recommendations and the strengths of a given hybrid proved to be an important way to reduce those risky overlaps.
Ultimately, by tuning into GEM, farmers can better safeguard their investments. As Ortez points out, the more sides of that triangle a farmer can stabilize or improve, the less likely a season’s worth of hard work and inputs will be undone by a field of problem ears.
Hear Ortez share more of his research on abnormal ear development in a recent podcast sponsored by the Crop Protection Network.
