Roundup Ready Soybeans

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Roundup Ready Soybeans (RR soybeans) are genetically engineered soybeans that have had their DNA altered to allow them to withstand the herbicide glyphosate (the active ingredient in Monsanto's herbicide Roundup). They are also known as "glyphosate tolerant" soybeans. RR Soybeans were first planted commercially in 1996. When planting RR soybeans, a farmer can spray the entire crop with glyphosate, killing only the weeds and leaving the soybeans alive. However, one concern with the heavy use of glyphosate on Roundup Ready Crops is that it will lead to the development of glyphosate resistant weeds (sometimes referred to as "superweeds").[1]

Impact of RR Soybeans

For more general information about the impact of Roundup Ready Crops, please see the article on Roundup Ready Crops.

Impact on Herbicide Use

Predictably, as farmers were now instructed to spray their entire soybean crops with glyphosate, the adoption of RR soybeans increased the amount of glyphosate use. However, as weeds also evolved glyphosate resistance and as "weed shifts" occurred, in which less susceptible varieties of weeds became bigger problems once more susceptible weeds were eliminated, farmers growing RR soybeans had to use ever higher amounts of glyphosate on their RR soybeans to control weeds. A leading weed scientist testified before Congress that "between 1996 and 2006, the amount of glyphosate applied per planted acre of soybeans in the U.S. increased from less than 0.2 to about 1.2 pounds, a six-fold increase."[2] At the same time more and more of the soybean crop was planted in Roundup Ready seeds each year, "The soybean glyphosate rate per crop year increased from 0.69 pounds per acre in 1996 to 1.36 pounds in 2006, or 9.8% per year. The average one-time rate of application rose 27% from 1996 through 2006, while the number of applications rose from 1.1 to 1.7, or 55%."[3]

Of course, total herbicide use measured in pounds is not a perfect measure, as herbicides are not all equal in toxicity. Glyphosate, for example, is seen as less toxic than many other herbicides. Unfortunately, as more and more acres are impacted by glyphosate resistant weeds, farmers have begun using other, often more toxic herbicides to deal with them. Because glyphosate resistant Palmer amaranth is often already resistant to other herbicides (such as ALS inhibitors), often the last option left are PPO Inhibiting Herbicides.[3]

Evolution of Glyphosate Resistant Weeds

As farmers adopted RR soybeans and increased use of glyphosate herbicides, weeds began evolving resistance to glyphosate as well. The first glyphosate resistant weed in soybeans discovered in the U.S. was horseweed (also known as marestail), discovered in Delaware in 2000.[4] Since then, it has spread to 20 other states (AR, CA, IA, IL, IN, KS, KY, MD, MI, MO, MS, NC, NE, NJ, OH, OK, PA, SD, TN, and VA) as well as soybeans in Brazil and Canada.[5]

More glyphosate resistant weeds in U.S. soybeans followed, with giant ragweed and common ragweed identified in 2004,[6] palmer amaranth and common waterhemp identified in 2005,[7][8] and johnsongrass in 2007.[9]

Palmer amaranth in particular is a big problem, as one plant can produce nearly half a million seeds.[3] It was identified in cotton and soybeans in Georgia in 2005, and it then spread to many other states (AL, AR, IL, LA, MI, MO, MS, NC, NM, TN, and VA).[10] In 2008, scientists found palmer amaranth that was resistant to both glyphosate and ALS inhibitors in soybeans in Georgia.[11] Since then, palmer amaranth with multiple herbicide resistances has been found in more U.S. states.

Impact on Crop Yields

One argument given in favor of planting Roundup Ready crops is that they will increase crop yields. However, a 2009 study found that the original Roundup Ready soybeans (MON 04032) "have not increased operational yields, whether on a per-acre or national basis, compared to conventional methods that rely on other available herbicides."[12]

The study explains its findings, saying:[12]

"Overall, studies have reported both increases and decreases in yield of GT [glyphosate tolerant] compared to non-GT soybeans, but the best-controlled studies suggest that GT has not increased — and may even have decreased — soybean yield. This is not necessarily surprising. The typical pesticide regimes and combinations of several herbicides used prior to the introduction of GT soybeans were generally effective, if inconvenient, in controlling weeds. Glyphosate has been effective against many species of weeds, and therefore more convenient because farmers can often avoid using several different herbicides and spraying schedules, but it does not necessarily provide better weed control than several other herbicides combined."

It also assesses Monsanto's second generation RR soybeans, MON 89788, saying:[12]

"Recently, Monsanto Co. announced the release of a new GT soybean, called Roundup Ready 2 Yield (RR2Y), that is claimed to increase yield by 7–11 percent over previous GT soybeans. Significantly, increased yield is the result of insertion of the gene for glyphosate tolerance in a way that avoids the negative yield effect of the original GT soybeans, and the use of a soybean variety that provides high yield due to conventional breeding methods (Meyer et al. 2006). GE in this case does not increase yields, but merely eliminates the previous yield reduction associated with the original HT-engineered soybeans."

Impact on the Environment

Impact on Human Health


For more detailed information, see the article on History of Roundup Ready Soybeans.




  • 2000: The first glyphosate resistant horseweed (Conyza canadensis) in the U.S. is discovered. They are found in the U.S. in soybeans.[16]
  • 2004: The first glyphosate resistant Giant Ragweed (Ambrosia trifida) and Common Ragweed (Ambrosia artemisiifolia) in the U.S. is discovered. They are found in the U.S. in soybeans.[17]
  • 2005: The first glyphosate resistant Palmer Amaranth and Common Waterhemp (Amaranthus tuberculatus (syn. rudis)) in the U.S. is discovered. They are found in soybeans and cotton.[18][19]
  • 2007: The first glyphosate resistant Johnsongrass (Sorghum halepense) in the U.S. is discovered. They are found in the U.S. in soybeans.[20]
  • June 27, 2007: Canada deregulates a new RR soybean variety from Monsanto, MON 89788.
  • July 23, 2007: U.S. deregulates MON 89788.
  • 2008: Monsanto introduces MON 89788 under the brand name "Roundup Ready 2 Yield®," marketing them as "the second generation of the popular Roundup Ready® technology farmers have used since 1996."[21]
  • July 24, 2008: US deregulates Pioneer Hi-Bred 's Glyphosate Tolerant soybean variety, Event 356043 soybeans.[22] In addition to being glyphosate tolerant, it is also tolerant of ALS Inhibiting herbicides..
  • September 23, 2009: Canada deregulates Pioneer Hi-Bred's Event 356043 soybeans.


Brands and Manufacturers


Adoption Rates

In addition to the U.S., as of 2011, Roundup Ready soybeans were grown in: Argentina, Bolivia, Brazil, Canada, Chile, Costa Rica, Mexico, Paraguay, South Africa, and Uruguay.[26] This list includes several of the world's top soybean producers, including Brazil (2), Argentina (3), Paraguay (6), Canada (7), Uruguay (8), Bolivia (10), and South Africa (13). The world's #1 producer of soybeans is the United States.[27]

Within the U.S., the adoption of RR soybeans by farmers grew following their 1996 introduction. The USDA offers data on the percent of soybeans in the U.S. that are herbicide tolerant between 2000 and 2012:[28]

  • 2000: 54%
  • 2001: 68%
  • 2002: 75%
  • 2003: 81%
  • 2004: 85%
  • 2005: 87%
  • 2006: 89%
  • 2007: 91%
  • 2008: 92%
  • 2009: 91%
  • 2010: 93%
  • 2011: 94%
  • 2012: 93%

Articles and resources

Related SourceWatch articles


  1. William Neuman and Andrew Pollack, "Farmers Cope With Roundup-Resistant Weeds," New York Times, May 3, 2010, Accessed February 18, 2011.
  2. Testimony of Michael Owen, "Are ‘Superweeds’ an Outgrowth of USDA Biotech Policy? (Part I)," Hearing, Committee on Oversight and Government Reform, U.S. House of Representatives, July 28, 2010.
  3. 3.0 3.1 3.2 Charles Benbrook, "Impacts of Genetically Engineered Crops on Pesticide Use: The First Thirteen Years" and Supplemental Tables, The Organic Center, 2009.
  4. Herbicide Resistant Weeds: Horseweed, Accessed August 18, 2012.
  5. Herbicide Resistant Weeds: Glycines, Accessed August 18, 2012.
  6. Herbicide Resistant Weeds: Giant Ragweed, Accessed August 17, 2012.
  7. Herbicide Resistant Weeds: Palmer Amaranth, Accessed August 17, 2012.
  8. Herbicide Resistant Weeds: Common Waterhemp, Accessed August 17, 2012.
  9. Herbicide Resistant Weeds: Palmer Amaranth, Accessed August 17, 2012.
  10. Herbicide Resistant Weeds: Glycines, Accessed August 18, 2012.
  11. Herbicide Resistant Weeds: Palmer Amaranth, Accessed August 18, 2012.
  12. 12.0 12.1 12.2 Doug Gurian-Sherman, "Failure to Yield: Evaluating the Performance of Genetically Engineered Crops," Union of Concerned Scientists, 2009.
  13. Federal Register, Vol. 59, No. 99, May 24, 1994.
  14. Novel Food Decisions - Approved Products, Health Canada, Accessed August 17, 2012.
  15. Daniel Charles, Lords of the Harvest: Biotech, Big Money, and the Future of Food, p. 163-164.
  16. Herbicide Resistant Weeds: Horseweed, Accessed August 17, 2012.
  17. Herbicide Resistant Weeds: Giant Ragweed, Accessed August 17, 2012.
  18. Herbicide Resistant Weeds: Palmer Amaranth, Accessed August 17, 2012.
  19. Herbicide Resistant Weeds: Common Waterhemp, Accessed August 17, 2012.
  20. Herbicide Resistant Weeds: Palmer Amaranth, Accessed August 17, 2012.
  21. Monsanto Company History, Accessed August 14, 2012.
  22. Federal Register, Vol. 73, No. 143, July 24, 2008.
  23. Product Safety Summaries, Accessed August 13, 2012.
  24. Federal Register, Vol. 76, No. 242, December 16, 2011.
  25. Petitions for Nonregulated Status Pending, USDA, Accessed August 9, 2012.
  26. Clive James, "2011 ISAAA Report on Global Status of Biotech/GM Crops," ISAAA, 2012.
  27. FAOSTAT, Search on Production of Soybeans by Quantity for 2010, Accessed July 16, 2012.
  28. Genetically engineered varieties of corn, upland cotton, and soybeans, by State and for the Unites States, 2000-12, USDA ERS.

External resources

External articles