Maximizing corn yield potential requires even and consistent plant-to-plant development so that each plant has an equal opportunity for limited resources such as water, nutrients and light. When one plant falls behind in development due to delayed emergence, unequal microenvironment or early season stress, that plant becomes less competitive for the limited resources and can often show up in delayed and smaller ear development.
This past planting season presented many challenges that may become evident in ear development and, ultimately, yield. Planting into wet and waterlogged soils may have created sidewall compaction and subsurface soil compaction layers that can reduce root growth and internal soil water drainage. Wet, residue-covered soils are cooler and can create pockets within the field with greater differences in microenvironments, resulting in larger separations in plant development (Figure 1). Additionally, nitrogen may have been lost due to leaching or denitrification, and other nutrients may be less available due to restricted root development.
Scouting corn fields prior to harvest is a good learning opportunity to identify these early season problems that may not have been so evident and easy to identify in midseason and late-season crop development. Additionally, late scouting can help identify the impact of the challenges that were evident throughout the vegetative stages of development. Look for plants that may be shorter in height, have lower ear placement and smaller stalk diameter, and have ears that may have been delayed in silking, pollination, and ultimately reduced kernel set (Figures 2 through 5). If plants with these symptoms are found, attempt to identify the cause. Dig roots to evaluate planting depth, look for restricted root growth horizontally and vertically and evaluate overall root health and evidence of root injury from disease and insects. Also, look at the soil surface for evidence of excessive residue, open seed slot or ponding of water. Finally, compare spacing between plants - unevenly spaced plants can accentuate growth inequities.
Looking directly at how ear development is affected by stressors earlier in the season can be a real eye-opener and learning experience. Identifying these issues late in the season cannot alter the outcome prior to harvest, but it can help address issues with planter settings, planting process, tillage, and future tillage needs. Stress identification can help with decision-making for the spring of 2020 when the true outcome in ear development and yield from planting into less-than-ideal soil conditions can be observed.
For additional information on pollination, please see Channel Agronomy ADVICE, Pollination and Fertilization in Corn. http://www.channel.com/agronomics/Documents/AgronomicContentPDF/PollinationandFertilizationinCorn_Channel_Advice.pdf.
Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.
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