The ability to apply a nonselective herbicide such as Roundup, Liberty or Touchdown without harming the genetically engineered crop has revolutionized weed control. More than half of all soybeans planted in the U.S. this year are transgenic. Such widespread use, warn Loux and his colleagues, can only lead to problems later. That's not to say you can't get away with using the same herbicide or mode of action for several consecutive years. But eventually weed species are going to respond and survive and adapt to the herbicide programs you use.
History certainly supports the scientist's warning.
Measurable weed shifts first appeared when the widespread use of 2,4-D in corn caused an increase in grasses. Fall panicum began to thrive from overuse of atrazine. In soybeans, cocklebur became more frequent after years of metribuzin treatments. Use of Pursuit in soybeans caused lambsquarters to increase. The most recent example of weed species adaptation is waterhemp.