In 2016, abnormal ear development was reported from several cornfields in Nebraska. In addition, well-substantiated reports extended from the Texas Panhandle to eastern Colorado and east through Kansas, Nebraska, Iowa, and Illinois. Similar issues occurred in Nebraska and other regions in subsequent years. Very little was known about what caused these abnormalities, challenging our understanding. Four projects phases studied abnormal ear’s underlying causes and their impact on yields. In phase one, two literature reviews were conducted to describe and summarize previously-reported symptoms, document the recent widespread symptoms of major concern, and study conditions potentially affecting corn ear formation, yield, and abnormal ears (Chapters 1, 2). In phase two, 15 surveys in South Central and Eastern Nebraska farmer fields characterized the 2016 reports (Chapter 3). In phase 3, experimental research was carried in 14 Nebraska distinct environments with different genetics and various management strategies to study the canopy level responses of abnormal ears (Chapters 4, 5). In phase four, morphological characteristics and plant yield differences between plants with normal and abnormal ears were studied at the plant level (Chapter 6). The overriding conclusions include 1) abnormal ears still plague cornfields, and it is essential to continue investigating the leading causes while identifying potential mitigation strategies; 2) abnormal ears are an observable limitation when trying to increase yields, depending on the frequency and severity of symptoms; 3) the selection of resistant hybrids and appropriate management are critical for crop adaptation, mitigation, and managing unfavorable conditions that can result in abnormal ears and lower yields; 4) plant morphological characteristics can help as diagnostic capacities to differentiate plants with normal and abnormal ears; 5) ear abnormalities should be understood as a result of the classic interaction among genetics (G), environment (E), and management (M). Fine-tuning G × E × M could help reduce and mitigate the likelihood of abnormal ears while increasing corn systems’ productivity, profitability, and sustainability
