Carter Charles manages insects and weeds in his corn fields near Cyrus, Minn., without the benefit of genetically modified seeds.

This is the third season he’s planted all conventional corn hybrids. Charles’ cropping strategy is a response to two developments on his farm: growing problems with glyphosate-resistant weeds and declining populations of corn rootworms and corn borers. In 2012, this approach put an extra $46/acre on his bottom line. “It’s not for everybody,” says Charles, who grows 900 acres of corn, soybeans and sunflowers and also runs an aerial crop-spraying business, “but this is working for me.”

After a decade of embracing biotech corn, Charles started questioning the need to keep using herbicide and Bt traits in his operation.

“My problem was that Roundup wasn’t killing my weeds, especially lambsquarters and waterhemp,” (the result of years of a Roundup-only herbicide program on every acre). “If I have to go to conventional herbicides, why am I paying for the technology to use Roundup?

“The other indicator was that my non-Bt refuge corn consistently yielded 6-8 bu. better than my Bt corn, even without insecticide. And it was one or two points drier at harvest. Also, my beetle counts were low, and I didn’t notice any lodging when I combined.”

With encouragement from his agronomist, Luke Griffith, Morris, Minn., Charles planted more conventional alternatives. Now, instead of using triple-stack corn to control pests, he relies on crop rotation, soil-applied insecticide, increased scouting and intensified weed management. “I’m saving a lot of money on seed, and putting it into machinery instead.”

Charles isn’t alone, says Agronomist Dorian Gatchell, Minnesota Agricultural Services, Granite Falls, Minn. In response to a lot of questions about this from growers, Gatchell ran some economic comparisons of conventional and traited corn from his clients’ 2012 fields. Returns on conventional corn were equal to or better than GM-corn, when corn followed soybeans, he says. “No one trait package was considerably better than the others.” Rather, “It is the genetics and the management of those genetics that make yield. Any differences can probably be attributed to differences in management.”

 

Bt and increased yields

Still, few growers are choosing to forgo traits entirely, as Charles has.

Genetically modified seeds accounted for almost 90% of corn plantings in 2012, while Bt hybrids were planted on two of every three U.S. corn acres. A 2012 study by the USDA Economic Research Service concluded, “Bt adoption is associated with increased profits and yields.” In 2010, for example, Bt-corn boosted yields by an average of 26 bu./acre and profits by about $118/acre, the USDA reports.

Demand for Bt corn continues to strengthen, says Tim Bratland, product manager for Legend Seeds, DeSmet, S.D. At the same time, demand for non-GM corn is up in parts of the northwestern Corn Belt, where marginal land, such as former grassland, is being put into corn production. On that less productive ground, “Growers don’t want to spend extra money.”