Moment of Truth Approaches for Corn Yield

CORN ILLUSTRATED: If you haven't harvested yet you likely will soon.

Published on: Sep 24, 2013

A lot of pluses and minuses have been said about this year's corn crop. It appears to be a big crop, but maybe not a record crop. Several factors have made this one hard to predict. The truth will soon be known. Some fields have already been harvested, especially in the Eastern Corn Belt. More will be harvested soon.

Early reports indicate that the crop may yield better than expected, even if it did fight off rainy periods early and dry weather late in the season. However, some of those early reports are from farmers who micro-manage the crop with fertilizers, tissue testing and fungicides to get the most yield per acre as possible.

Here are factors making it hard to know what's in your field.

N shortage: Plants running out of nitrogen may have capped yields in some fields.
N shortage: Plants running out of nitrogen may have capped yields in some fields.

Late start: Many fields were planted later than normal due to a wet spring. However, past history says corn planted in mid-May in the central Corn Belt can still yield well if the rest of the season is favorable.

Split personality: The weather was generally cool and wet during pollination. That favors big corn yields. However, it turned hot and dry in many areas in August and early September. That favors somewhat lower yields since kernels abort at the tip, and existing kernels may not be filled as plump as if the grain fill period was favorable.

Mixed bag on disease: No big outbreaks have been reported, but conditions were favorable for white mold to form during the middle part of the season. Once it takes hold it can continue to grow even if the weather turns dry. Expect to see some of it. How much you see may help determine yield and quality.

Mixed bag on insects: The phones were quiet in the Entomology Extension office at Purdue University, but they rang off the wall in Illinois. Mike Gray of the University of Illinois an entomologist who got lots of calls, especially from a couple counties in central Illinois, where fertilizer dealers and farmers suspected that rootworm was breaking through the genetic control mechanisms.

Nutrient shortages: Nitrogen is probably the key nutrient in this year's discussion about corn yield. Since the spring was wet, those who made early applications of N likely lost part of it. However, even those who sidedressed later saw corn with classic N deficiency symptoms on the leaves. Consider this a wild card factor that may or may not affect your yield.