Source: Iowa State University

Two Iowa State University researchers question if the industry expects too much from a corn hybrid or a specific stacking of traits when they are grown over fields that vary so significantly.

In 2009, 57 percent of Iowa's corn crop was stacked gene varieties and seven out of eight fields were planted with one or more transgenic traits, according to USDA statistics. In 2010, producers across the country may plant 3 million to 4 million acres of hybrids with eight genetic modifications for insect control and herbicide tolerance, SmartStax. 

Original press release.