![thumbnail image](https://extension.entm.purdue.edu/newsletters/pestandcrop/wp-content/uploads/sites/2/2019/09/corn1.png)
Delayed planting of corn in the upper Midwest often increases the risk that the grain will not mature prior to a killing fall freeze. Physiological maturity occurs near the time the so-called “black layer” develops at the tips of the kernels where they connect to the cob (Nielsen, 2019a).