If you have more acres of corn to plant, plant earlier if seedbed and environmental conditions allow, say Iowa State University Extension agronomists.
Last year 50% of the crop was planted by April 25. Research has shown a small yield loss with early planting dates and a larger yield loss with later planting dates.
Research from 1998-2000 showed that planting approximately between April 20 and May 20 resulted in 100% yield. Newer research (2003-2006), finds corn can be planted before April 20 and reach 100% yield.