Corn Not All It’s Stacked-Up to Be?

The stacked corn traits farmers pay big bucks for are not keeping rootworms from munching on their favorite food.  On the positive side, genetically modified corn stops another pest, corn borer, in its tracks, and the technology produces towering plants that produce excellent yields, said University of Illinois (UI) entomologists Mike Gray and Kevin Steffey.

In mid-July, Gray, Steffey and their student assistants began digging up corn plants in UI fields to look at their root system health, an annual ritual for these scientists who study pests that feed on the state's largest crop.  Gray was cited as saying that project overseer Ron Estes called their attention to the surprising difference in height between one transgenic variety (much larger and productive) that contains B.t. proteins engineered to kill both corn borers and rootworms, and its counterpart without the B.t. traits.

The second surprise is that rootworms did significant early damage to transgenic varieties.  Gray said they started digging up roots to evaluate damage in July as well as August for a very specific reason - a severe storm that swept through in July a few years ago and flattened a lot of corn fields, a sure sign rootworms have been at work in the ground.  Steffey said that the technology introduced in 1996 that works so well for corn borers, killing about 99 percent of the beetles that eat it, doesn't work as well on rootworms, technology which was launched in 2003, adding, “You don't get the expression in the roots that you get in the leaves,” and that many companies don't emphasize that fact when they're selling their stacked hybrids to farmers.  Gray said studies show B.t. slows rootworms down and kills some, but “you get survivors.”  (The News-Gazette, 7/13/07).