Diversity is an important strategy to mitigate risk. In corn production, this means choosing diverse hybrid genetics to hedge against weather, disease or pest-related risks that might affect any particular product. However, because more seed companies are licensing hybrids from a single source, growers often do not get the genetic diversity they expect in their corn line-up.
The growing concentration of germplasm sources in the industry raises the possibility of similar genetics appearing in hybrids from different companies, and fewer truly different, top-performing hybrids.
Extension corn specialists see this as a serious problem. According to Emerson Nafziger, University of Illinois professor and Extension agronomist, corn growers typically plant a number of hybrids to spread risks. "Because growing conditions aren't very often near perfect, and we can't predict when a certain stress will occur, we plant different hybrids as insurance," Nafziger explains.
"The major stress we try to deal with in corn is during the pollination period," says Joe Lauer, professor and Extension corn agronomist at the University of Wisconsin. "And it's a very narrow window of time, usually about eight days beginning in the middle part of July through the beginning of August. If you plant all of your corn on all of your acres with one hybrid on the same day and hit a period of stress during pollination, then all of your corn is vulnerable." To reduce this risk, growers can either spread out planting dates or select hybrids with different maturities. This helps ensure that separate fields go through the pollination stage at different times, Lauer explains.
Diseases and other pest pressures also are major risks for corn production, Lauer says. "You can have different diseases or pests on the farm, based on its particular environment," he explains. "It pays to pay attention to the disease-resistance of hybrids and select for your field the best resistance package possible. Otherwise, you could have some trouble. It's important to have different genetics in your fields because of different disease and pest pressures in general." "Every hybrid has one or two sensitivities, and so planting diverse genetics — as long as this doesn't require using hybrids that carry obvious problems — is a sound management practice," Nafziger says.
Identical and Closely Related Hybrids
Choosing genetically diverse hybrids is a goal for most growers, but actually achieving diversity is often difficult. That's because growers could buy two hybrids with different brands and names yet they contain the same genetics, according to Lauer and Nafziger.