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Angie Peltier

Angie Peltier
Former Extension Educator, Commercial Agriculture

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Hill and Furrow

Current topics about crop production in Western Illinois, including field crops research at the NWIARDC in Monmouth.
Figure. A picture of root lodging due to a combination of rootworm pruning damage, saturated soils and wind. See me in the background below the arrow for perspective.
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Wind + saturate soils = lodging: Will lodging affect grain dry-down and harvest?

At various locations throughout the state, the Illinois State Water Survey (ISWS) collects wind speed measurements using an instrument called an ultrasonic anemometer. This device measures the speed of airflow every 10 seconds. The ISWS collects the average wind speed for each hour of the day. They also note the highest wind speed for each day. In the midst of receiving 2.8 inches of rain over August 22 and 23, on August 23, winds as high as 51 mph were recorded!

From the second half of August until now, each week has brought rain and/or strong storms to western and central Illinois.

Wind + Saturated Soils = Lodging. Many acres of both soybean and corn at the Northwestern Illinois Agricultural Research and Demonstration Center (NWIARDC) have lodged. In some soybean varieties with a very thick, full canopy, plants are laying more than 45 degrees from vertical. These plants may spring back up when they lose their leaves.

However, more worryingly, corn plants in many fields throughout the NWIARDC are also lodged. The lodging that we are observing originated from roots rather than stalks. In the field housing Dr. Mike Gray's rootworm trial, the lodging is near 100 percent in much of the field (Figure). This is due to root pruning damage (Figure) and a combination of water-logged soils and high winds. In a recent Bulletin article, Dr. Gray highlighted the very high rootworm pressure and the possibility of the arrival/evolution of the Bt-resistant western corn rootworm population at the NWIARDC.

In other fields, particularly with certain hybrids, there was little to no root pruning, but the water-logged soils and high winds resulted in significant root-lodging (Figure).

Although we have not yet seen evidence of stalk lodging, those hybrids that had severe foliar disease symptoms are at risk for stalk rot and lodging. Guidelines for scouting fields for stalk-lodging potential are available here.

The lodged corn at the NWIARDC may provide an indication of the need for crops scouting to gauge the potential for dry-down and harvest difficulties throughout the region this fall.

How quickly might grain drying occur in lodged corn? Once corn plants reach physiological maturity (ie. when kernels have a black abscission layer form between the kernel and the cob), kernels are still between 25 and 40 percent moisture. To minimize both the risk of kernel damage during harvest and some of the costs associated with drying very wet grain, producers typically allow grain to dry to lower moisture levels in the field.

The time that grain takes to dry down depends upon many factors including hybrid ear and husk of the characteristics and weather conditions. In an online article, Dr. Bob Nielsen of Purdue University provides a very thorough discussion of the ear and husk characteristics that can affect dry-down. Weather-wise, warmer air is capable of holding more water and the higher the temperature and the lower the relative humidity, generally the faster the rate of dry-down. Downed ears are either much nearer to or in direct contact with the soil. This makes the grain in lodged plants less exposed to wind and sun, making for slower moisture loss. As downed ears can remain wet for longer periods and may be exposed to rain splash from soil and plant residue, they may have a higher risk for some grain molds than other ears.

Very good information about how quickly physiologically mature corn grain can lose moisture is available in an article called "How fast can corn dry down?" written by Iowa State University Agronomist Dr. Roger Elmore and Lori Abondroth.

According to Elmore and Abendroth,

"On average, typical seasonal drying rates range from 0.4 to 0.8% moisture loss per day. If the fall months vary from normal in terms of temperature or moisture, the rate of dry down will differ. For example, wet and cool weather will delay drying. We've recorded seasonal dry down rates less than 0.3 % per day. On the other hand, warm dry weather speeds drying rates. Kernels could lose up to 1.0% moisture per day. Considering that corn at maturity has about 30% moisture content it could easily take 2 to 4 weeks for grain moisture to drop to 15%.

Hybrids will vary in rate of dry down as well. Drying rates of later maturing hybrids or late-planted corn are slower than earlier maturing hybrids or early-planted corn. This is partly because the corn matures when days are shorter in length and temperatures are usually cooler".

Harvesting lodged corn. Ask anyone that has harvested severely lodged corn and they will tell you what a nightmare it is as it is difficult to do and time-consuming and even done carefully grain can be left in the field. Several articles have been written both highlighting the components of yield loss during harvest of lodged corn and how best to minimize each component and prioritize harvest:

Stay in contact with your crop insurance agent. The USDA Risk Management Agency urges those producers that may have had crops affected by wind, heavy rain events and/or flooding to contact their crop insurance agents within 72 hours of discovering damage. During this conversation producers can report damage and discuss possible options, procedures and deadlines.

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