Effects of Frost on Corn

Effects of Frost on Corn

In the Field with Mr. Agronomist


Chad Hermelbracht

A wet 2019 spring and volatile markets left producers scratching their heads on when and what to plant in their saturated soils. Those farmers who were lucky enough to get their crops planted most likely did so later than they wanted. This later planting date shifted the crop maturity later into the year. Cloudy days and cooler weather pushed maturity back even further. As we approached harvest, we are running anywhere from 2-4 week behind average for corn production. Now we are faced with a cold front and freezing temperature at the beginning of October. Some areas are even dealing with snow. What does this mean for our crops in the field?

Yield losses that occur from frost injury depend on a couple factors, how cold and length as well as what stage the corn is at. We are a couple weeks behind normal and most corn is in the dent stage nearing black layer. Black layer is when the kernel is at its physical maturity and no longer receives any nutrients from the plant. It severs the connection. Frost will not hurt yield if it occurs after black layer. It will however slow dry down. After black layer, the corn plant is still alive and helping draw moisture out of the kernel. If the plant is killed by frost, then kernel is then going to rely solely on evaporation to dry. With cool and wet conditions, there will be very little drying done.

If the kernel has not reached black layer, a killing frost will stop all development. This can severely hurt yield, primarily test weight. The grain will be higher moisture, possible misshapen kernels, and prone to damage during mechanical drying. See the below chart for possible yield losses.

A killing frost will not severely hurt a producer’s yield if back layer is reached, but one must be mindful of the harvest challenges that we will face after the frost sets in. Dry down will be slower and less mature corn has potential to be lighter test weight. With wet field conditions, take your opportunities to harvest when possible. Understand what stage the crop was at right before the frost. This will aid in harvest timing, drying, and marketing.
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