The historic derecho storm event that passed through the corn belt on August 10, 2020 left a wide path of destruction. Millions of acres of corn across IA, IL and areas of WI were affected. There are a few key considerations and takeaways to keep in mind when managing wind-damaged corn:
- The growth stage of the crop at the time of weather event is a key factor in yield impact.
- Whether the plants experienced root lodging or stalk-crimping impacts the grain fill potential.
- Yield losses due to reduced harvestability should be expected.
Root Lodging
The most significant issue that resulted from the storm is root lodging, which occurs when high winds force the corn roots to lose hold and the plant tips over at the soil line without breaking. The incredibly high winds, with significant downdraft, flattened corn fields (shown right). The problem is worsened in saturated soils, often brought about by heavy rains that can accompany a large thunderstorm.
Factors that can contribute to root lodging:
- Hybrid tolerance to lodging (increasingly bred to withstand greensnap or stalk lodging).
- Poor early season root development caused by compaction, excessive/saturated early season soil moisture, delayed planting dates, high seeding rates or poor seed spacing at planting.
- Corn rootworm feeding damage.
Stalk Bending Between Nodes
In addition to root lodging, many fields encountered stalks bending or crimping between nodes. It’s important to understand that in these scenarios, the plant is no longer able to transport nutrients to the developing ears. This will impact the normal grain fill process and result in much greater yield loss, slowed dry-down and reduced test weight. If the wind event occurs later into the season, during or after grain fill, then yield loss is likely to be reduced.
Growth Stage at Time of Damage
The corn growth stage plays a significant role as to how the plant responds to root lodging or bent stalks. Prior to tasseling, corn internodes are still elongating. Root lodging prior to tasseling will induce a plant growth hormone response resulting in “goosenecking” of stalks as the plant begins to regrow upright. Auxin, a plant growth hormone, encourages stalk elongation on the side closest to the soil to help the plant begin to grow vertically again.
The August 10 wind event occurred post-pollination for the majority of fields. Due to plants now focusing on grain fill, corn will have minimal goosenecking back up from soil surface, making harvest even more challenging.
What to Expect Based on Crop Stage at Time of Wind Event: - V13-15: Plants begin to gooseneck upward rapidly within 6 days of event, minimal affects on harvestability, and a 5-15% yield reduction may occur.
- During pollination (VT): Pollination can be reduced, causing poor kernel set. Disruptions of photosynthesis at key timing results in greater yield loss potential. Minimal goosenecking and increased impact on harvestability. A 12-31% yield reduction may be expected, most likely on the higher end of the range if pollination/kernel set is affected.
- Post-Pollination/Grain Fill: Light, nutrients and soil moisture can be greatly reduced during important grain filling stages. Stalk quality may deteriorate quickly, due to reduced photosynthesis and the reallocation of nutrients within the stalk to the developing ear to better support grain fill. Plants will no longer gooseneck upward, increasing harvest challenges. Little data exists on yield impact of corn lodged at the R2 growth stage in which the majority of corn was in on August 10th. University of Wisconsin trial results suggest up to 25% yield reduction as late as R1. Greater yield losses are unlikely if just root lodged. Additional yield losses due to harvestability should also be expected.
Harvestability and Adjustments to Consider
In addition to physiological yield reduction, harvest losses can be quite large in some situations. Harvestable yield will be impacted depending on how much the nodes below the ear can adjust and raise the plant off the ground. When root lodging occurs post-pollination, goosenecking will be minimal. Root-lodged corn usually requires slower harvest speeds and has the potential for further yield loss from ear loss during harvest. Lodged corn will likely be more predisposed to stalk rots. As the plant cannibalizes the stalk for nutrients due to reduced soil nutrient uptake, it is more vulnerable to stalk rot diseases, which can further impact the harvestability of the lodged corn.
For more information on managing wind-damaged corn, contact your local
Golden Harvest Seed Advisor or agronomist.
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