Stick With Normal Hybrid Corn Maturities For Now

Corn growers should stick with their normal hybrid maturities rather than switch to earlier-season maturities through the end of May, says a University of Missouri Extension corn specialist.

Frequent, excessive rainfall has delayed planting statewide. But Brent Myers advises growers to hold steady.

“A shortened growing season does not necessarily translate into a need for a lower maturity rating,” he said, noting that research has shown that late-planted corn matures in fewer calendar days than early-planted corn of the same hybrid.

“Relative maturity ratings apply to corn adapted or selected for a specific region that is planted ‘on time,’” he said.

The timing of corn growth and development is mainly controlled by the temperature. Corn needs to accumulate a minimum number of “thermal units” across the growing season to reach physiological maturity.

“But there is a big difference between the effective thermal units in a typical late-April day than in a typical late-May day,” Myers said. “Later-planted corn is developing in a different thermal environment than its relative maturity was designed for.”

In a study published in 2002, researchers in Indiana and Ohio planted corn on three dates between late April and June. The later-planted corn, both short- and long-season hybrids, matured an average of nine days before earlier-planted corn.

Myers said that corn’s yield potential has begun to decline slightly because of planting delays, but opportunity remains for a good growing season.

After the end of May, yields begin to drop by 20 percent, and by 40 percent by mid-June. When corn planting is delayed past mid-June, corn growers may want to consider other crops, Myers said. But until then, stick with plans to plant corn.

source : missouri.edu