Roundup Ready Corn

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Roundup Ready Corn (RR Corn) is genetically engineered corn that has had its DNA modified to withstand the herbicide glyphosate (the active ingredient in Monsanto's herbicide Roundup). It is also known as "glyphosate tolerant corn." RR corn was first deregulated in the U.S. in 1997 and first commercialized in the U.S. in 1998. Roundup Ready Crops and genetically modified organisms (GMOs) are controversial around the world. One variety of RR Corn, NK603, was linked to tumors in rats by a 2012 study.[1]

Study Links RR Corn to Tumors in Rats

On September 19, 2012, a team led by Gilles-Eric Séralini of the University of Caen published a study called "Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize" in the journal Food and Chemical Toxicology.[1] The study ran for two years, studying the effects of Monsanto's Roundup Ready corn variety NK603 and/or Roundup herbicide on 200 rats. Only 30% of males and 20% of females in the control group died during the experiment, compared to much higher rates of mortality among treated rats.

"Up to 14 months, no animals in the control groups showed any signs of tumors whilst 10–30% of treated females per group developed tumors, with the exception of one group (33% GMO + R). By the beginning of the 24th month, 50–80% of female animals had developed tumors in all treated groups, with up to 3 tumors per animal, whereas only 30% of controls were affected. The R [Roundup] treatment groups showed the greatest rates of tumor incidence with 80% of animals affected with up to 3 tumors for one female, in each group."[1]

The study found that the first large detectable tumors occurred "at 4 and 7 months into the study in males and females respectively, underlining the inadequacy of the standard 90 day feeding trials for evaluating GM crop and food toxicity (Séralini et al., 2011)." (emphasis added)

For more information on this study, see the article on the NK603 variety of corn.

Roundup Ready Corn Brands and Manufacturers

The following companies sell Roundup Ready corn under the brand names listed below.[2]


Dow Agrosciences and Pioneer Hi-Bred:

Pioneer Hi-Bred (DuPont):[3]

  • Optimum® AcreMax® RW Rootworm Protection (DAS 59122-7 and NK603)
  • Optimum® AcreMax® Insect Protection (YieldGard Corn Borer, TC1507, and NK603)
  • Optimum® AcreMax® Xtra Insect Protection (YieldGard Corn Borer, TC1507, DAS59122-7, and NK603)






  • 2010: Monsanto releases a new line of products called Genuity, including several varieties of Roundup Ready Corn, and both Monsanto and Dow introduce a Roundup Ready product called "SmartStax."

As of 2012, the USDA is evaluating petitions to deregulate the following glyphosate tolerant corn varieties:[7]

Adoption Rates in the U.S.

Following the introduction of Roundup Ready corn, its adoption by U.S. farmers grew. The USDA offers data on the percent of corn in the U.S. that is herbicide tolerant between 2000 and 2012:[8]

  • 2000: 7%
  • 2001: 8%
  • 2002: 11%
  • 2003: 15%
  • 2004: 20%
  • 2005: 26%
  • 2006: 36%
  • 2007: 52%
  • 2008: 63%
  • 2009: 68%
  • 2010: 70%
  • 2011: 72%
  • 2012: 73%

Articles and resources

Related SourceWatch articles


  1. 1.0 1.1 1.2 Gilles-Eric Séralini, Emilie Clair, Robin Mesnage, Steeve Gress, Nicolas Defarge, Manuela Malatesta, Didier Hennequin, Joël Spiroux de Vendômois, "Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize," Food and Chemical Toxicology, Available online September 19, 2012.
  2. A Compendium of Biotech Corn Traits, Purdue University, Accessed August 12, 2012.
  3. Optimum AcreMax, Accessed August 13, 2012.
  4. Determinations of Non-Regulated Status, USDA, Accessed August 9, 2012.
  5. Monsanto Company History, Accessed August 12, 2012.
  6. Monsanto Company History, Accessed August 12, 2012.
  7. Petitions for Nonregulated Status Pending, USDA, Accessed August 9, 2012.
  8. Genetically engineered varieties of corn, upland cotton, and soybeans, by State and for the Unites States, 2000-12, USDA ERS.

External resources

External articles