Illinois farmers are ready for the corn planting race to begin.

A few early planters were out in late March, with this Prairie Farmer editor spotting a 24-row corn planter in a Sangamon County field on Wednesday, March 28. The big planting rig was working near Illiopolis, just south of I-72. Fields on this stretch between Springfield and Decatur are typically among the first to be planted in the state.

But for those Illinois farmers who purchased crop insurance, the green flag to start planting isn't until Friday, April 6. That's the earliest date you can plant corn and maintain coverage. You need to keep that start date in mind if you're using it to cover any frost or issues related to stand establishment.

Planters will be rolling this week, especially if the weather and soil conditions are right.
While the University of Illinois has long warned farmers of the risks associated with planting early, it is revisiting its past research that the best time for planting corn in the northern half of Illinois is in the last week of April.

Significant improvements made in today's hybrids prompted researchers to re-examine the corn planting date question. For the past two years, the University of Illinois has been conducting studies of planting dates at five or six locations in the state. Planting dates ran from early April through late May.

Planting date responses are notoriously variable depending on seasonal weather notes U of I Agronomist Emerson Nafziger. But with a few exceptions, planting from mid-April through early May has produced the highest yields.

In 2006, the highest yields were produced by the earliest planting date in four of six locations. At the other two locations (Urbana and Monmouth), the second and third planting dates yielded more than the first date. This difference was 12 bushels at Monmouth, where the first date was April 5.

At Urbana, the March 30 planting yielded 40 bushels less than the April 24 planting. "We think it's likely that the first planting at this location was large enough to be damaged in some way by the cool, wet conditions in mid-May, while later plantings did not have plants large enough to be similarly damaged," says Nafziger.

Excluding that instance, results over the past two years indicate that planting in the last half of April is the best time to plant. When planting is delayed past late April, yield responses have ranged from slight increases to about 1 bushel less per day of delay.

The U of I plans to continue its research on planting dates.