By Greg Roth
Professor of Agronomy
After last week’s frost event I received feedback and made some observations myself about the variable nature of the damage. In some cases it was fairly striking. These have caused some questions about why this variation occurs.
Some fields escaped damage completely while others were nearly completely burned back to the ground. Patterns among fields and within fields were often related to slope and elevation, with low areas and north slopes having the most damage. These are likely due to cold air settling in these pockets. Residue also made a difference. In one low field on our research farm, soybeans were completely killed by the frost in areas with heavy grain residue, but suffered only about 50% mortality where silage plots had been harvested and there was little residue.
Residue on right resulted in complete soybean mortality due to frost in this field.
In a demonstration plot, rows of corn next to the grass were injured while those in the middle of the plot were not. In these cases, the heat transfer from the soil to the air was limited by the grass and the residue and likely made enough difference to really impact injury.
Other patterns were not so easy to explain. In one demonstration, rows of some hybrids were completely burned off, while adjacent rows of another hybrid were untouched.
Dramatic differences of frost tolerance of adjacent corn hybrids.
It’s surprising to me that this much variation in response occurred. Some producers also reported striking differences in injury within the row, which was likely due to a combination of factors like the ones discussed above.
As expected most corn has recovered nicely, but some injured soybeans have not.
Corn recovering well from frost damage.
In some fields, soybeans are recovering from damage from axillary buds where they were not completely killed. These plants should be fine if mortality in the field is limited and the remaining stand is adequate.
I did not get to scout any wheat fields but have discussed the potential of freeze injury in wheat previously. You can read that article here.I would monitor suspect crops for grain development following flowering to see if the frost caused any injury. My suspicion is that most fields were still in the boot stage and not injured significantly.