Pioneer studies also showed similar results. The company focused on hybrids planted across the central, north-central, north and far-north regions of the Corn Belt. Hybrids were planted from early April to mid-June and grouped into full, medium and early maturities at each location. Several hybrids were included in each maturity group so that true maturity responses could be measured. The studies looked at differences in corn grain yield response to planting date, as well as moisture, test weight and gross income response.
For example, in the central Corn Belt, Pioneer's study results indicate that early to mid-April planting is best for the greatest corn yield potential. Full-season hybrids – hybrids with a comparative relative maturity of 111 to 115 – yield better and produce better grain at harvest than early maturity hybrids, Pioneer said.
Pioneer recommends full-season hybrids until the last week of May in the north-central Corn Belt, and full-season hybrids in the northern Corn Belt until approximately May 27.
Purdue's Nielsen also offers recommendations for farmers needing to weigh a hybrid decision, and noted that development is very dependent on temperature. His research shows that relative to a May 1 planting date, hybrids planted later mature approximately 6.8 fewer growing degree days for every day of delay beyond May 1.
"That response of hybrid development relative to delayed planting means that normal full-maturity hybrids can be safely planted later than one would think and, consequently, means that growers can avoid switching to earlier maturity hybrids until planting dates later than one would think," Nielsen writes.
Though May is already in full swing, agronomists expect farmers to catch up fast once the weather comes around. Nielsen estimated late last week that when farmers do get in the fields, 25% to 30% of the corn crop could be planted in a week and the rest a week later, still in time for maximum yield potential.
Both Nielsen and Pioneer note that growers with specific questions about maturity and selection should consult their seedsman.