Late planting is a game changer for corn

Anyone with gray hair remembers “To Tell the Truth.” Three people claiming to be the same person attempted to stump a celebrity panel. Only one of the three was the real person. This summer features “To Tell a Hybrid,” with the same hybrid looking different depending upon when it was planted.

Key Points

Late-planted and early-planted corn of the same hybrid look different.

Later-planted corn of the same hybrid matures faster.

Typically, later-planted corn of the same hybrid yields less.


Certain characteristics won’t change. If the tassel on Hybrid X has few spikes that typically stick upward, it will have few spikes that stick upward, no matter when it was planted. And if plant leaves are erect, they will still be erect.

Telltale signs

“Late” planting is relative. Basically, we’re talking about corn planted before May 10 vs. corn planted after May 20. We’ve done such a good job convincing people that early planting pays that many panicked soon after May 1. You can still raise a good corn crop planting later, depending upon weather in July and August.

Mother Nature makes the adjusting on late planting. Her No. 1 desire is to produce as many mature babies (embryos in kernels) as possible, even if that means shortening the growth phase.

For corn planted after May 10, expect these adjustments in the same hybrid:

Change in leaf number. There will be fewer leaves. The emphasis shifts toward reaching maturity vs. building the largest factory possible.

Taller stalks. The internodes, or stem between each node, will be longer than if the same hybrid is planted earlier.

Quicker flowering. It will happen after an accumulation of fewer growing degree day units, which are a measure of heat units, than if the hybrid was planted before May 10.

Faster maturation. Bob Nielsen at Purdue University and Peter Tomlinson at Ohio State University demonstrated that late-planted corn of the same hybrid can take up to 200 fewer growing degree days to reach black layer.

Lower yield. Odds favor lower yield. You can’t rule out that yield might have been higher planted earlier, even if it yields 200 bushels per acre when planted May 25, unless you have strips of the same hybrid in the same field planted on or before May 10.

Corn will be wetter. Moisture content at harvest will likely be higher. Late-September and October weather determine just how much wetter corn will be.

Today vs. yesterday

There are trade-offs in how today’s hybrids should handle late planting vs. those of 20 years ago. Modern hybrids have more vigor and grow and mature faster, all factors that should help offset late planting and very high harvest-moisture content.

However, today’s GMO hybrids with built-in insect protection, coupled with fungicide applications, tend to stay healthier longer. In this particular situation, that tends to delay maturity.

Nanda is a crops consultant based in Indianapolis and director of genetics and technology for Seed Consultants Inc. Reach him at Nanda@
seedconsultants.com
, or call him at 317- 910-9876.

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Reach for sky: This corn was planted during the last week of May in 2010. Due to longer internodes, it is taller than if it had been planted April 25.

This article published in the July, 2011 edition of INDIANA PRAIRIE FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.