Planting Decisions May Be Changing with the Weather

DuPont Pioneer research finds even in late May planting situations, full-season hybrids may still be best choice

Published on: May 7, 2013

According to Purdue Extension corn specialist Bob Nielsen, this spring's planting season has been so slow it's among the five slowest years for spring planting in the last 20 years.

That's no surprise, given the amount of precipitation that has blanketed the Corn Belt states in the past three weeks, causing flooding situations, impeding field-dry out and generally making fieldwork next to impossible.

But despite the wet conditions in many areas, some producers are determined to get into the field as quickly as possible to avoid more hits to their crops' yields, but they could be filling the planter with hybrids they didn't originally choose.

DuPont Pioneer research finds even in late May planting situations, full-season hybrids may still be best choice
DuPont Pioneer research finds even in late May planting situations, full-season hybrids may still be best choice

The question of switching hybrids due to a late start has several variables, and several outcomes. Nielsen said a switch would be to hybrids that don't take as long to reach maturity, but the tradeoff could potentially be lower yields.

Nielsen notes a related concern with delayed planting of full-maturity hybrids is the risk of high moisture at harvest and the resulting costs of drying or price discounts.

According to research prepared by DuPont Pioneer, however, adapted full-season corn hybrids still offer the best yield and profit advantage when planting delays aren't extreme.

Mark Jeschke, DuPont Pioneer agronomy research manager, noted that it is important to weigh your decision carefully.

"If you switch to a shorter season hybrid too soon, you are giving up higher yield potential and profits," he said.

Pioneer said university research shows that full-season hybrids adjust to late planting with a reduction in their growing degree unit requirement of up to six units per day of planting delay. For example, hybrids planted May 20 may require 150 fewer heat units to reach maturity than the same hybrids planted April 25. This adjustment reduces the risk of fall frost damage to these hybrids.

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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.