Monsanto’s Bt corn was supposed to reduce pesticide use. The Environmental Protection Agency said as much when the corn, which is genetically modified to resist the crop-ravaging rootworm, debuted in 2003. Sure enough, as more farmers sowed their fields with Bt corn, fewer of them needed to spray pesticides to protect their crops. The share of U.S. corn acreage treated with insecticides fell from 25 percent in 2005 to 9 percent in 2010.
But now, Bt corn has become, basically, too successful: Rootworms are starting to develop immunity to this prevalent crop, driving farmers to return to insecticide use. The Wall Street Journal reports:
Syngenta, one of the world's largest pesticide makers, reported that sales of its major soil insecticide for corn, which is applied at planting time, more than doubled in 2012. Chief Financial Officer John Ramsay attributed the growth to "increased grower awareness" of rootworm resistance in the U.S. Insecticide sales in the first quarter climbed 5% to $480 million.