Full-season Hybrids Did Better Planted Early

All hybrids yielded poorly at late-May planting date.

Published on: Dec 17, 2007
One of the studies in the exclusive Corn Illustrated project this year was a small-plot study designed to figure out what relative maturity of hybrids works best at a range of planting dates. Or put differently, should you plant early hybrids first, or plant late or full season hybrids first? And if you get caught and are still planting corn later in the season, which maturity range of hybrids should you try to obtain from your seed dealer and then plant on your farm?

Dave Nanda, president of Bird Hybrids, LLC, Tiffin, Ohio, long-time plant breeder and consultant for the Corn Illustrated project initiated by Farm Progress Companies, set up the experiment to demonstrate what he's seen in other years. And even though the year turned out to be extremely stressful where the plots were located, Edinburgh, Ind., the results, in terms of trends, were similar, just more pronounced in some ways, Nanda notes.

These plots were not irrigated. The soil was a medium-textured loam, but with sand and gravel starting at three feet below the surface. Only 5 inches of rain fell on the plots during the growing season, most of it coming in mini-showers. Temperatures soared in August and September. Overall, Jim Facemire, the cooperating farmer, recorded roughly 41 days of 90 or higher F readings on a weather station supplied by Spectrum Technologies, Plainfield,.Ill. The average number of days at or above the 90 degree F level in south –central Indiana is about 18.

The test consisted of planting Bird Hybrids of four different maturities, ranging from 104 days to 119 days in relative maturity, at three different planting dates. The planting dates were May 7, May 17 and May 29. Each test consisted of two one/1000th of an acre of each entry. The entire experiment was replicated once at each planting date.

The earliest-planted plot excelled early and then ran into trouble about tasseling time near the end of July. By early August, it was showing obvious stress. At that same time, the latest-planted plot still showed surprising stamina, with green stalks and leaves, seemingly only showing minor symptoms of stress. However, instead of getting the relief in rain and a break in heat it was waiting for, the temperatures climbed and rainfall totally dried up. Only about 0.4 of an inch of rain fell on the plot from the end of July through September 10. Soon, the latest-planted plots gave up. They were harvested on Sept 17.

"Yields on the latest-planting rep were all extremely low, down in the 50 bushel per acre more or less," Nanda reports. "You expect yields to drop for later-planted corn, but this was a more sizable drop than usual. Scouting told us that silk clipping was not an issue, nor any other insect factor. This was simply a case of running out of moisture and suffering extreme stress at a critical period in the growth stage."