The 2008 corn growing season has busted some long-held corn production “truths.”

Although the list could go on and on, here are nine commonly held beliefs that were either disproved during 2008 or in 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? What agronomic and environmental criteria should be used to select the best population for a specific farm? Our 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 – narrows here refer to those less than 30 inches wide. However, I’ve not seen corn yields reduced in narrow rows compared to 30 inch rows either.
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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 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. We aren’t sure what happens at very high yield levels.

Myth #8 – Transgenic traits increase yields.
Not so. What these traits do is allow the crop to grow to its potential, but it does 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 tunneled by European corn borers.

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 http://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.

Editor’s Note: This list was compiled from a recent interview with Iowa State University Extension communications specialist Doug Cooper and then written as a news release by Iowa State University Extension communications specialist Willy Klein.