University of Illinois

No. 2/April 3, 1998

How Early Should We Plant Corn?

With wet weather continuing into early April, it appears that the question nof early planting will not be as common as it was in 1997. Here are some points to consider about planting corn in April:

--Based on research in Illinois, yields of corn are generally highest when the crop is planted up to a week earlier or later than the last week of April, then yield losses begin to accelerate. Our work showed yields an average of 3 to 5 bushels per acre lower for corn planted in mid-April.

--Even with slightly lower yields with early planting, most farmers will proceed to plant in the first 2 weeks of April to finish on time. Delays in late April due to weather push planting later than the optimum and also delay soybean planting. Risk management, in other words, favors early planting.

--Even though we worry about placing corn seed in soil when temperatures are in the 40s, experience--particularly that in 1997, when it stayed quite dry after planting--has shown that the crop usually emerges well under such conditions. We thus no longer use soil temperature as a guide to planting after April 1, but we strongly recommend that soils be dryenough to allow placement of seeds into good soil conditions. Planting into mud is never a good idea, but it can be a disaster if done when soils are cold as well. In addition, excessive soil compaction from working and planting wet soils may decrease yields some years.

--Very early application of some insecticides and herbicides may mean loss of activity and less protection of the crop.

--Although we never want to replant corn, very early planting may allow replanting, if needed, to be done early enough so that little yield is lost.

Keep in mind that very good yields are still possible even if planting is delayed until mid-May. But once soil conditions are good for planting in April, there probably should be little hesitation in getting started.
Emerson Nafziger, (, Crop Sciences, (217)333-4424