Still Weeks Away From Switching Hybrids

Stay with original plans as long as you can.

Published on: May 13, 2009

Questions started trickling in to agronomists as early as the first week of May. The callers want to know if they could exchange long-season corn hybrids for earlier-maturing hybrids since planting date is delayed this year.

Bob Nielsen's pat answer is 'no.' The Purdue University Extension corn specialist says that since hybrids can adjust and mature more quickly with less GDDs than the same hybrid could if planted earlier, there is no need to panic. It's possible yield might slip some, but based on last year's observations, it's still possible to have a good year.

"What we don't know is what the weather will be like during the rest of the season," says Dave Nanda, plant breeder and president of Bird Hybrids, Tiffin, Ohio. "Last year we saw a late start in many areas, but yields still turned out well for the most part," he notes.
What matters is what weather patterns develop and dominant during the key summer months. The key period for corn reproduction, even with a delayed start in planting, will still come in mid-July. "We'll have to wait and see what the weather is like then," Nanda says.

At some point, should the continuous on -again, off-again rain shower pattern continue, it might be necessary to switch to earlier hybrids, Nielsen notes. Nanda agrees, However, both believe that will likely be the end of May, not now. "Yields may not be as high due to delayed planting, but the crop will still mature based on Nielsen's findings," Nanda says. Peter Thomison at Ohio State University contributed to that important research a few seasons back. Nielsen and Thomison found that the same hybrid can shorten the number of growing degree days it needs to mature by up to 200, or nearly 10% of the total number of GDDs most hybrids require to reach maturity, if maturity is delayed.

A rush to switch to earlier hybrids could have unintended consequences. Not all companies have ample quantities of earlier hybrids. Some specialize in fuller-season hybrids, and have only limited inventories of hybrids that would be considered early maturity hybrids. Those companies might be hard-pressed to locate enough seed for customers if a switch becomes absolutely necessary.

For now, the word from Nielsen is not to panic. Warm May days can change the situation in a hurry. The next couple weeks may go a long way toward revealing how this season will play out, and how it will be remembered.