Having issues with kernel set in your corn this year? Kernel abortion and incomplete pollination issues have popped up in a lot of fields in the Corn Belt this year, especially after the dryness and heat of July and much of August.

"Zipper ear" is a common type of incomplete kernel development and grain fill. It causes a few rows of the ear's kernels to abort altogether, giving the pattern its name, as it resembles a zipper. So, why exactly does it happen? According to Purdue University Extension agronomist Bob Nielsen, crop drought stress is the culprit, but what about issues like "zipper ear," when only a few rows of the cob don't develop?

There's no real explanation, but Nielsen speculates zipper ear stems from the way the silks fall on the ear during pollination.

"This leads me to speculate that perhaps the draping of the silks resulted in the underlying silks being shaded from initial contact with pollen," he says in a university report. "That may have led to those silks never coming into contact with pollen or those silks being pollinated later than the rest."

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So, if you've got kernel development issues like zipper ear, what can you do? There's not much to do for this year's crop, obviously, but there are ways you can prepare for next year, Nielsen says.

"The only suggestion I can give is to try to reduce soil compaction so it will take more time for drought conditions to damage the plants," he says. "Soil compaction limits root growth and keeps the plants from getting water. Plus, reducing compaction is a best management practice that farmers should be working on every year."