Just as the heavy use of antibiotics contributed to the rise of drug-resistant supergerms, American farmers' near-ubiquitous use of the weedkiller Roundup has led to the rapid growth of tenacious new superweeds. To fight them [farmers] are being forced to spray fields with more toxic herbicides, pull weeds by hand and return to more labor-intensive methods like regular plowing. We're back to where we were 20 years ago," said [farmer Eddie] Anderson. Farm experts say that such efforts could lead to higher food prices, lower crop yields, rising farm costs and more pollution of land and water. The first resistant species [was found] in 2000. Since then, the problem has spread, with 10 resistant species in at least 22 states infesting millions of acres. The superweeds could temper American agriculture's enthusiasm for some genetically modified crops. Roundup Ready crops account for about 90 percent of the soybeans and 70 percent of the corn and cotton grown in the United States. However, if Roundup doesn't kill the weeds, farmers have little incentive to spend the extra money for the special seeds. "The biotech industry is taking us into a more pesticide-dependent agriculture when ... we need to be going in the opposite direction," said Bill Freese, a science policy analyst for the Center for Food Safety in Washington. Roundup-resistant pigweed ... could pose as big a threat to cotton farming in the South as the beetle that devastated the industry in the early 20th century.