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Alien Invasion: Attack of the Superweeds

Glyphosate, the main ingredient in Monsanto's Roundup herbicide, has spawned a new generation of superweeds that are spreading rapidly across the United States.

Since farmers planting Monsanto's genetically engineered Roundup Ready crops no longer need to worry about overdosing their crops with herbicide, they tend to spray more of it. And just as antibiotic overuse has resulted in antibiotic resistant drugs, constant use of Roundup and its active ingredient, glyphosate, has given rise to an epidemic of glyphosate resistant superweeds.


Scientific Name: Conyza canadensis 


  • Named after its resemblance to a horse's tail blowing in the wind
  • Causes skin irritation in humans and livestock
  • Grows up to nine feet tall
  • Produces up to 250,000 tiny, super mobile seeds per plant
  • Affects cotton, soybeans and, most recently, corn
  • Infests more than three million acres in 16 states
  • Reduces cotton yields by 40 to 70 percent
  • Hosts tarnished plant bugs, a major cotton pest
  • Regarded as a "worst case scenario" in Roundup Ready cropping systems


Scientific Name: Palmer amaranth 


  • Named after its preference for growing in pig pens with lots of manure
  • Spreads rapidly amongst cotton, soybeans and corn fields across the southern U.S.
  • Known to be "aggressively invasive"
  • Grows as tall as a man and as thick as a baseball bat
  • Destroys everything in its path, including harvesting equipment
  • Produces up to 450,000 seeds per female plant
  • Spreads via flooding, farm machinery, wind and long-distance pollen flow
  • Withstands up to seven applications of glyphosate
  • Drives fed-up farmers to abandon their fields


Scientific Name: Ambrosia trifida 


  • Named after its deeply indented or "ragged" looking leaves
  • Torments people who suffer from hay fever
  • Resides in six states: Ohio, Arkansas, Indiana, Minnesota, Kansas and Tennessee
  • Grows up to 16 feet tall
  • Considered most competitive broadleaf weed in Indiana soybean production
  • Destroys crop yields up to 70 percent with just three to four plants per square yard
  • Attacks soybean and cotton plants by spreading seeds with prolific force
  • Spotted recently in Canada
  • Compels farmers to rely more heavily on tillage and dangerous herbicides, like 2,4-D


illustrations by Matt Lau