Don't Forget Disease Resistance When Choosing Corn Hybrids

December 19, 2006

COLUMBUS, Ohio -- Disease resistance shouldn't be overlooked when choosing corn hybrids for next season, especially if growers plan to make the switch to continuous corn.


Peter Thomison, an Ohio State University Extension agronomist, said that corn planted following corn, especially in reduced tillage systems, increases the risk for disease buildup because of inoculum left behind in residue. As a result, choosing hybrids with disease-resistant packages becomes that much more important.

"A lot of growers are expressing interest in planting corn following corn next year and they are looking for characteristics in hybrids that are good for that production system," said Thomison, who also holds a partial research appointment with the Ohio Agricultural Research and Development Center. "Disease resistance is the No. 1 trait they should be looking for in conjunction with yield potential."

Incidences of foliar diseases such as gray leaf spot and northern corn leaf blight, diplodia and fusarium ear rots, and stalk rots can all intensify under continuous corn production.

Several sources exist for growers searching for the right traits to protect their crop. One such source is the Ohio Corn Performance Trials -- tests conducted annually by OSU Extension that evaluate hybrids based on a variety of performance characteristics, such as yield potential, percent moisture, stalk lodging, emergence, and test weights of the grain. The results help growers select hybrids that not only yield well, but can also perform well across a variety of environmental factors and growing conditions.

This year's tests covered 225 hybrids representing 38 commercial brands. Hybrids with disease resistance packages were tested, along with transgenic hybrids that house stacked traits resistant to corn rootworm and other insects. Complete results are available at

"Growers have no control over the weather and in a continuous corn cropping system, fungi are always present, so the only thing growers can control when it comes to minimizing disease development in their crop is selecting hybrids with good resistance and good stalk strength," said Pierce Paul, an Ohio State University OARDC plant pathologist. "Growers might think that it's not a priority to take disease into consideration, but you can still take a yield hit in any given year if you plant a highly susceptible hybrid, especially in a corn following corn cropping system."

The following are some tips growers can follow when selecting hybrids with disease-resistant packages:

• Choose varieties that show resistance to the more common diseases in Ohio, such as gray leaf spot and northern corn leaf blight.

• Choose hybrids with good stalk strength.

• Look to a variety of sources when deciding which hybrids to choose, from the Ohio Corn Performance Trials, to seed companies, to data from neighboring states.

• Choose hybrids with disease resistance rated on a scale, rather than on a "good" plant health description. Thomison said that hybrids with "good" plant health are too general and not sufficient to providing the information needed to make an informed decision on which hybrids work best for a specific farmer's situation.

• Analyze hybrids over several locations to see how well they performed, and preferably use two years worth of data. Also use the performance of the hybrids planted by yourself and your neighbor as a guide.

In Ohio, continuous corn production is uncommon. Thomison estimates that less than 15 percent of the corn planted in the state follows the previous year's corn crop. He added that it's important for growers to realize the potential problems associated with continuous corn, and the best way to minimize those problems starts with hybrid selection.

Candace Pollock
Peter Thomison, Pierce Paul