A superweed is not a hero clad in tights, bright colors and a cape. On the contrary, it brings devastation to farmers across the Midwest. To prevent misconceptions that stem from using slang words, the Weed Science Society of America (WSSA) has defined the term “superweed” as:
“Slang used to describe a weed that has evolved characteristics that make it more difficult to manage due to repeated use of the same management tactic. Over-dependence on a single tactic as opposed to using diverse approaches can lead to such adaptations.”
In layperson’s terms, superweeds have developed resistance to common herbicides from repeat use of a single mode of action. These can cause yield and profit losses where resistance is high.
To those not familiar with the term superweed or weed resistance, this term can lead to confusion and false assumptions. For example, one misconception is superweeds resulted by gene transfer from genetically modified crops. Another is these weeds are brand new species that have super-powered competitive characteristics.
(Source – http://www.agweb.com/article/no-superpowers-for-superweeds-NAA-sonja-gjerde/)