On Chuck Grassley's Corn twats. Iowa Corn dot Org. has this handy quote:
When is corn harvested?
In Iowa, some farmers begin harvesting corn by mid-September, though most of the harvest is takes place in October. In a cool year, when the corn matures more slowly, much of Iowa's crop isn't harvested until November. Harvest times can vary a great deal because different corn hybrids take different lengths of time to mature. Even when plants are physically mature, farmers might wait to harvest them until corn kernels have dried further so that the corn can be stored for longer periods of time.
Waiting for the kernels (colonels?) to dry (up).
https://www.iowacorn.org/education/faqs