Farmers in the U.S., Canada, and Argentina are expected to slash their plantings of genetically modified (GM) crops by 20 to 25 percent this year because of growing uncertainty in the market, the Worldwatch Institute said yesterday. A growing number of food manufacturers and retailers have said they will stop selling foods containing GM ingredients. Last month, a straw poll of 400 farmers by Reuters found that they planned to plant 24 percent less Bt corn and 22 percent less RoundUp Ready corn, two widely used GM crops. The U.S. Agriculture Department said last week that grain buyers were paying eight to 10 cents more per bushel of non-GM corn in Illinois than for GM corn. Meanwhile, biotech companies are bringing fewer new GM crop varieties to market. A scientific advisory panel to the EPA this week recommended that the U.S. government conduct more testing and monitoring of GM crops to ensure they aren’t killing butterflies and other unintended insects.