Here are problems you could run into, even if you didn’t think your crop was stressed much this summer:
Poor kernel set. This can definitely happen in stressed fields, but sometimes it happens even if fields didn’t appear that stressed, Bob Nielsen notes. There’s a two- to three-week window from pollination through early kernel development where kernel set is determined. If pollination isn’t effective, or if kernels abort, you’ll find ears with missing kernels.
Silk clipping. Both corn rootworm and Japanese beetles are quite capable of clipping silks short enough to interfere with pollination. It all comes down to when the beetles were active and how many were in the field.
Wet tassels. If you were lucky enough to get moisture this summer, but unlucky enough to get showers or rain every day during pollination, the pollination process could have been affected.
Tip dieback. You’re talking about kernel abortion. A small amount is expected and may vary by hybrid. An inch or more of unfertilized cob at the tip may indicate that stress or some other factor, such as warm nights during early grain fill, caused kernel abortion.
Source: Wisconsin Agriculturist, September 2011