Uneven corn is somewhat common across west central Iowa and is especially noticeable in lighter soils with residue cover.

In one field I noticed V6 corn right next to V4 corn and 12 inch corn right next to 6 inch corn. To confuse the matter I found three V5 plants that were 6, 8 and 12 inches tall. So, not only did we have variance in growth stage, but also shoot elongation.

So what happened? Here’s my take on the situation. The corn was planted into ideal or nearly ideal conditions. Lack of moisture at emergence was not an issue. But as the surface soil dried up with below normal amounts of rainfall in May the corn plant may have been limited in moisture at a critical time during nodal root formation.

Let’s add salt to that wound. Some of the worse cases of uneven corn had two additional strikes against them; first was lighter soils and second was either no-till or high residue conditions. The light soils had less moisture available for the plant while the residue effected planting performance. Most notable on planter performance was variability in seed depth placement. Some of the shortest corn both in height and growth stage had shallow seed depth.

The residue also created micro-environments for warmth and moisture. With residue cover there were cooler, wetter zones and without residue the zones were drier and warmer. And we all know what cool and wet does to plant development… it slows it down.

With moisture over the weekend and early this week in addition to predictions for warmer weather by weeks end, I would suspect that the plants will grow out of the unevenness with shorter plants elongating more to compensate for height as warmer weather becomes abundant.

It is too late to think about starting over, but one could expect a 5 to 25% yield hit. Of course this would depend much delay there is between plants and how long the unevenness persists. For more information go to Yield Effects of Uneven Corn Height by Roger Elmore, ISU Corn Specialist.

SOURCE: ISU’s Mark Licht