Part of my job as Stine’s technical product agronomist is to work with our regional sales agronomists throughout the Midwest. This gives me an excellent opportunity to hear about the management systems and tips that are working well across all regions. It also puts me in a unique position to hear of regional issues that affect crop performance, from weather to insects to diseases. Over the next two weeks, we will focus on significant issues noted throughout the 2018 growing season. To start, we’ll focus on corn.
Significant Issues Noted in Corn
In 2018, several unique phenomena have been observed:
- Summer heat early in large parts of the Midwest, followed by cooler, wetter weather patterns.
- Higher than average minimum or overnight temperatures affecting plants.
These weather patterns caused unique diseases to infect earlier and in more widespread areas. They also caused unique responses from all plants including those infected. In corn, those issues included:
- Tar Spot (affecting large areas in Indiana, Illinois, Wisconsin and Iowa)
- Nitrogen cannibalization in corn causing deteriorating stalks
- Apical Dominance Abortion (low ear syndrome)
Tar Spot
Many areas in the upper Midwest experienced tar spot in corn, otherwise known as tropical disease of corn. This disease is prevalent in equatorial regions and is rarely seen in the Midwest. However, with early heat and tropical storms in the South, the disease was carried North. Best practices for managing this disease moving forward will be to select corn hybrids with tar spot tolerance. The University of Illinois and the University of Wisconsin have been collecting samples for rating tolerance to this yield robbing disease. I do not expect an outbreak in 2019; however, we cannot rule it out, as Mother Nature is very unpredictable.
Nitrogen Cannibalization
Parts of Iowa and Illinois experienced strong wind events in July and August, which led to large areas of green snap. In addition, drought was also a major factor because it made nitrogen scarce near tassel time. Tassel is a critical time for nitrogen, so the plants were forced to take it from the stored reserves in the stalks, causing the stalks to become less rigid and more brittle. Conducting soil tests to know both phosphorous and potassium values mitigates this problem. In addition, having adequate sulfur available with nitrogen applications enables more efficient uptake, and utilization of the existing nitrogen can also help in this area. The final component is planting hybrids specifically developed to withstand adverse conditions with exceptional standability and green snap scores.
Apical Dominance Abortion
Growers in certain areas reported hybrids with extremely low ear placement. This phenomenon occurs with unusually hot, dry conditions just prior to tassel when the apical dominance of the corn plant is being determined. The weather conditions caused the primary node to abort in favor of lower node, which is supposed to occur later during plant development. There is no management tip to help with this condition; this is a function of environmental conditions during a specific growth stage in corn.
Check back next week when we focus on prevalent issues found in soybeans in 2018.