Low commodity prices make it more important than ever to protect corn yields, point out seed company representatives.

Gene Kassmeyer, Garst product manager, notes that it does not take much yield increase, even with $2 corn, to pay the technology fee for Bt corn.

"In most years, in most areas, we see at least a 5-bu/acre loss from corn borers," he points out. "Usually it's more. Farmers, historically, haven't recognized that loss because it wasn't visible."

Pioneer's 1997 studies show the return for planting Bt hybrids can range from $11/acre with low infestations to $75/acre with severe infestations. That's assuming a 150-bu yield and $2 corn, less a $7/acre tech fee.

"We split 20,000 stalks at 18 locations to develop the database for these conclusions," reports Steve Butzen, Pioneer agronomy information specialist.

Historically, he says, entomologists have estimated yield loss at 5%/borer/plant. Using that data, Bt hybrids would provide a $45/acre return, assuming a 150-bu yield, three borers per plant, $2 corn and a $7 tech fee.