AMES, Iowa -- The 2008 corn growing season has busted some long-held corn production “truths,” according to Roger Elmore, professor of agronomy with research and extension responsibilities in corn production. During a recent interview with Iowa State University Extension communications specialist Doug Cooper, Elmore listed nine commonly held beliefs that were disproved during recent years.
Myth #1 - Planting late-April through early-May will increase yields. In 2008, some of the best results were from corn planted late-May to early-June.
Myth #2 - When it comes to seeding rates – higher is better.
Agronomically that is still true. But when you think in terms of economics, with seed prices double what they were two years ago, seed prices along with yield responses must be taken into consideration before planting at higher rates. What is the optimum population for maximum yield as compared to economic yield? And what agronomic and environmental criteria should be used to select the best population for a specific farm? Elmore says research results should be available in the next couple of months. Right now it looks like the best yields on average in Iowa occur with 34 to 37 thousand plants per acre. With high-priced seed, producers may want to back off from these densities.
Myth #3 - Narrow rows increase yields.
It is hard to find proof in Iowa that there is a benefit to narrow row corn, i.e., rows less than 30 inches. However, corn yields are not reduced in narrow rows either.
Myth #4 - Early silk results in higher yielding corn.
Silking in 2008 happened two to three weeks later than usual, yet 2008 Iowa yields are tied for the third best in history of recorded yields; credit has to be given to the ideal weather after silking.
Myth #5 - Cool August chills yields.
Simply put, 2008 yields disproved this old thinking.
Myth #6 - Tasseling precedes silk.
With our new hybrids, this is not always true. Tassels are smaller than 20 to 30 years ago. They often are not fully emerged before silks appear and pollination begins.
Myth #7 - Uniform spacing within rows increases yields.
There is no research behind this belief at yield levels up to and over 200 bushels per acre.
Myth #8 - Transgenic traits increase yields.
Not so. These traits allow the crop to grow to its potential, but do not increase the potential yield! They protect yield, not increase it.
Myth #9 - Bt hybrid residue – European Corn Borer Resistant - decomposes more slowly than traditional corn residue. In research trials, they decompose at the same rate. The only time non-Bt hybrid decomposes faster is when stalks are bored by European corn borer.
While not typically known as myth busters, Iowa State University Extension researchers do bring the latest research in Iowa crop production to those that need it. Crop producers and managers can stay informed by subscribing to the Integrated Crop Management (ICM) newsletter at www.extension.iastate.edu/cropnews. The newsletter, with articles and interviews regarding current crop management issues, is updated regularly during the growing season to meet the needs of Iowa crop producers and managers.