Tweaking crop DNA has been good for Monsanto (NYSE: MON). The agricultural technology giant saw its fiscal 2006 revenue climb 17% to $7.3 billion, thanks in large part to ongoing growth in its corn seed and traits business. The success is impressive, but recent comments from a General Mills (NYSE: GIS) executive suggest that unless it takes action soon, Monsanto might have trouble maintaining its torrid growth rate. Not everyone is a fan of Monsanto. Plenty of folks have raised questions about genetically modified (GM) crops' impact on human health and the environment, even as millions regularly consume foods containing GM ingredients. In the U.S., concern over GM foods is relatively muted, in part perhaps because most consumers probably aren't aware that they are buying and eating such products.