A center-pivot irrigation system sprays water over a field of corn in Hopkins Park, Illinois, U.S., on Friday, July 6, 2012. Corn prices jumped to a nine-month high of $7.13 a bushel on the Chicago Board of Trade yesterday and have surged more than 37 percent since June 15 as a crop-damaging drought in the U.S. Midwest shows no signs of abating. Photographer: Daniel Acker/Bloomberg
Corn plants damaged by extreme heat and drought conditions stand in a field in Carmi, Illinois, U.S., on Wednesday, July 11, 2012. Photographer: Daniel Acker/Bloomberg
A center-pivot irrigation system sprays water over a field of soybeans in Hopkins Park, Illinois, U.S., on Friday, July 6, 2012. Corn prices jumped to a nine-month high of $7.13 a bushel on the Chicago Board of Trade yesterday and have surged more than 37 percent since June 15 as a crop-damaging drought in the U.S. Midwest shows no signs of abating. Photographer: Daniel Acker/Bloomberg