Abnormal ear development in corn: Does hybrid, environment, and planting date matter?

Corn (Zea mays L.) yields have increased historically, but production concerns still exist. For decades, abnormal corn ear development symptoms have been reported. Most of these reports have not been addressed through research, perhaps due to low occurrence and challenges in replicating them. In 2016, widespread abnormal ear development (multiple ears per node, barbell-ears, and short-husk ears) issues were reported in several cornfields in the Texas Panhandle, Eastern Colorado, Nebraska, and other US Midwest states. Fields with a high frequency of abnormalities resulted in lower yields. To investigate causal factors, a field trial was established to study the effect of hybrids, environments, and planting dates on abnormal ears. The project was conducted at two Nebraska sites during the 2018, 2019, and 2020 growing seasons. Six hybrids, six environments, and four planting dates were studied. Approximately 59,200 plants were individually assessed at the dent stage (R5). Abnormal ear percentages ranged from 0% to 45% per plot, with a mean of 6.66% across all conditions. Interactions among hybrids, environments, and planting dates were documented despite the overall low incidence of abnormal ears. Grain yields ranged from 5.2 to 22.5 Mg ha⁻¹; hybrids with higher abnormal ear percentages were associated with lower yields. The main documented symptom was short-husk ears. Abnormal ears were often placed at lower heights in the plant relative to normal ears. The results presented here demonstrate the importance of studying abnormal ears and understanding the impact of planting dates and hybrid selection as potential strategies to mitigate abnormal ears.