Wheat grows in a test field at Oregon State University in Corvallis. Some scientists believe that there's a chance that genetically modified wheat found in one farmer's field in May is still in the seed supply.
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Russ Kremer with some of his hogs on his farm in Frankenstein, Mo., in 2009. Instead of buying conventional feed, Kremer grazes his hogs in a pasture, and grows grains and legumes for them.
Jeff Roberson /AP
Protesters demonstrate against the production of genetically modified food in front of a Monsanto facility in Davis, Calif., in March. The local protest was not specifically about labeling.
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Farmer Alan Madison fills a seed hopper with Monsanto hybrid seed corn near Arlington, Illinois, U.S. A group of organic and other growers say they're concerned they'll be sued by Monsanto if pollen from seeds like these drift onto their fields.