The corn is "firing"

I have lived in the central Illinois farmland for over 35 years now and listen to farm reports on the radio regularly - since they give great weather reports.  I just recently heard a new farm term that was new to me.  Someone said - the corn is firing - well I had to ask what that meant of course.  It is when the corn begins to dry up and turn that lovely shade of brown.  Well, the corn is firing for sure and the harvest is starting.  I have seen fields which are opened up a bit, a few rows on the edge of the field which have been gathered in by the corn pickers.  Beans are drying up also - they would have liked a lot more rain when they were green, but that didn't happen this year.  So I imagine it will be a bit more of a skimpy harvest.