When Do Corn Yields Begin to Decline With a Late Planting Date?

Richard Taylor, Extension Agronomist; rtaylor@udel.edu

With the five-day forecast for New Castle County showing a chance of light rain or showers all five days, a grower asked me when to expect corn yields to begin to decline. Some of the work done in the past with planting dates indicate that the “ideal” planting window for corn, where you can expect maximum yields, is April 25 to May 10, although those dates will vary slightly as you move from north to south in the state. Many growers have developed the habit of planting corn very early and are therefore a bit concerned that we are moving from mid-April to late April with little accomplished in the northern portions of Delaware. Southern Delaware missed some of the recent rains and growers there were able to go full out planting corn this week, while many in the northern sections of the state were again delayed with wet, cold soils.

We all hope that the weather will cooperate soon so the corn and bean crops can be planted on time; but, for those not constrained by large acreages to plant, the good news is that there are still several weeks to go in the ideal corn planting window. Once we get past mid-May, corn yield potential does begin to decline — slowly at the beginning but rapidly as we move into June.


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