Herbicide tolerant crops
Herbicide tolerant (HT) crops are the biggest selling GM crops. These crops have been made to be tolerant to either Monsanto's weedkiller RoundUp (glyphosate) or Bayer's weedkiller Liberty (glufosinate ammonium). These are broad spectrum herbicides which kill all green plants except those protected as a result of the genetic modification. Recently, the first crops tolerant to Dow's 2,4-D, a more toxic weedkiller, have been approved for commercial growing in South Africa.
Monsanto's RoundUp Ready soybeans are the leading product. Other herbicide-tolerant crops include maize, sugar beet, and oil seed rape (canola).
Herbicide-tolerant GM crops have been attractive to the biotechnology companies as they have been able to
- sell both the herbicide and the GM seeds as a package
- place the same gene sequences into each of these major crop types
- gain intellectual property rights over the modified seeds and thus charge an annual technology fee.
Herbicide-tolerant GM crops have been attractive to a number of large-scale farmers in North and South America because in the early years after adoption they simplified the spraying regimes i.e. farmers only had to spray them once with with one type of herbicide, saving labour costs. However, repeated blanket applications of the same herbicide have led to herbicide-resistant superweeds evolving. These superweeds are now reducing crop yields and require repeated applications of multiple herbicides and sometimes even pulling up by hand. There are concerns about the impacts on of pesticide residues on human health, on wildlife, and on farmers' livelihoods.
The existence of superweeds is now being used by the companies involved to justify developing new GM crops tolerant to other herbicides, which may be even more damaging. "The weed resistance problems currently infesting U.S. farms are rapidly getting worse, and growers need new technology now to maintain productivity. Within the past year, the number of weed-resistant farm acres in the U.S. has increased by about 25 percent." Dow AgroSciences USA press release, April 2012.
In the USA, agro-chemical and GM seed companies now recommend that farmers use tank mixes of multiple herbides to try to tackle the superweed problem.
In 2012, South Africa approved Dow's GM maize (corn) engineered to be tolerant to the weedkiller 2,4-D (one of the ingredients in Agent Orange). The controversial GM maize, plus the same trait engineered into soybeans, are awaiting approval in the USA. The crops are intended to be planted in response to the spread of superweeds tolerant to Monsanto's weedkiller RoundUp (glyphosate), which have arisen due to use of the company's RoundUp Ready GM crops. In the short term, this will allow the superweeds to be killer by 2,4-D, but in the longer term resistance to this weedkiller will also develop. A significant increase in the use of 2,4-D is expected, leaving toxic residues in the food chain and damaging neighbouring crops due to drift during spraying.
In late 2012, Dow announced plans to introduce GM soybeans which are tolerant to three different weedkillers.
In South America, local people and some scientists have raised concerns about the health effects of being sprayed with the herbicides used on GM soya. Much of this soya is exported to Europe for use in animal feed.
In the UK, the Farm Scale Evaluations ran from 1999-2004. Herbicide-tolerant GM sugar beet, maize and oilseed rape (winter and spring) were grown along side conventional crops to monitor their ecological effects. The studies found that the changes in herbicide use associated with growing these GM crops had negative effects on wildlife.
- Press articles
- ABC News: Glyphosate resistance on the rise in Australia (15th May 2013)
- The Guardian: Tracking the causes of monarch butterfly decline (18th April 2013)
- Mother Jones: Monsanto Claims to Ditch Herbicide While Selling More of It (10th April 2013)
- Huffington Post: My War Against GM Crops (24th March 2013)
- Farmers Weekly: US farmers may stop planting GMs after poor global yields (6th February 2013)
- UPI: Resistant weeds said threat to U.S. crops (4th February 2013)
- Farm Industry News: Glyphosate-resistant weed problem extends to more species, more farms (29th January 2013)
- Reuters: UPDATE 1-Dow's controversial new GMO corn delayed amid protests (18th January 2013)
- Agriculture.com: New GM corn delayed until 2014 (18th January 2013)
- The Western Producer: Scientist raises concerns about GM crops and glyphosate (21st December 2012)
- Mother Jones: Meet the Weeds That Monsanto Can't Beat (20th December 2012)
- GRTV: Farmer to Farmer: The Truth About GM Crops (17th December 2012)
- New York Times: Pesticides: Now More Than Ever (11th December 2012)
- The Guardian: European Commission could open GM pandora's box (7th November 2012)
- Guardian: How GMOs unleashed a pesticide gusher (3rd October 2012)
- Independent Science News: Seralini and Science: an Open Letter (2nd October 2012)
- Reuters: Pesticide use ramping up as GMO crop technology backfires: study (1st October 2012)
- Daily Mail: Russia suspends import and use of American GM corn after study revealed cancer risk (29th September 2012)
- The Guardian: Study linking GM maize to cancer must be taken seriously by regulators (28th September 2012)
- BBC News: Agent Orange chemical in GM war on resistant weeds (19th September 2012)
- The Grocer: Monsanto Roundup weedkiller and GM maize implicated in 'shocking' new cancer study (19th September 2012)
- The Telegraph: GM crop enquiry launched by French government (19th September 2012)
- Deutsche Welle: Soy production endangers Argentina (3rd September 2012)
- IOL News: Controversial GM mielies get green light (24th July 2012)
- Mother Jones: USDA Prepares to Green-Light Gnarliest GMO Soy Yet (18th July 2012)
- Science News: Glyphosate-Resistant 'Superweeds' May Be Less Susceptible to Diseases (17th July 2012)
Reuters: US House biotech proposal would bypass courts - critic (5th June 2012)
Reports plans to re-start plantings of GM sugar beet in the US, while court cases are ongoing.
- Nature: War on weeds loses ground (22nd May 2012)
- Daily News Tanzania: Superweeds caused by GMO are super problems (20th May 2012)
- Superweeds: A Long-Predicted Problem for GM Crops Has Arrived (15th May 2012)
- Ottawa Citizen: Reaping what we sow (12th May 2012)
- Reuters: Super weeds no easy fix for US agriculture-experts (10th May 2012)
- San Francisco Chronicle: Genetically modified crops' results raise concern (30th April 2012)
- New York Times: A Battle Over an Engineered Crop (25th April 2012)
- Farmers Weekly: US growers petition government over GM crops (25th April 2012)
- Reuters: Analysis - Dow's new corn - "time bomb" or farmers' dream?
- Delaware Online: As Roundup's effect fades, farming costs rise (17th April 2012)
- Summit Voice: Popular weedkiller causes deformities in amphibians (3rd April 2012)
- StarTribune: Study ties GMO corn, soybeans to butterfly losses (16th March 2012)
Mother Jones: How NPR Got It Wrong on Monsanto's Superweeds (14th March 2012)
Includes some history on how Monsanto's RoundUp Ready trait was discovered.
- Penn State Live: Integrated weed management best response to herbicide resistance (9th February 2012)
- Bloomberg: Monsanto Says Weedkiller-Resistant Kochia Found in Western Canadian Fields (12th January 2012)
- Farmers Weekly: Resistance to Roundup is increasing (7th November 2011)
- Forbes India Magazine: Bt Brinjal and India's Wake-up Call (20th October 2011)
- ArabNews.com: Super weeds pose growing threat to US crops (19th September 2011)
- Wallaces Farmer (USA): Glyphosate-Resistant Weeds Are Huge Challenge (9th August 2011)
- St Louis Today: Resistant weeds leave farmers desperate (17th July 2011)
New York Times: In Midwest, Flutters May Be Far Fewer (11th July 2011)
Reports that the growing use of herbicide-tolerant genetically modified crops is threatening the monarch butterfly by destroying the milkweed on which it lays its eggs.
The Guardian: Global food crisis: the speculators playing with our daily bread (2nd June 2011)
Dan Basse, president of AgResource (Chicago) tells the Guardian that the promise that biotech seeds would deliver big increases in yields has turned out to be illusory. He also fears that "superweeds are coming on so fast with GM that US farmers are going to have to go back to more traditional cultivation methods [as opposed to the practice with GM seeds of not tilling the soil and simply spraying to control pests] - but they don't have the capacity to do that."
- The Telegraph: GM soy: the high cost of the quest for 'green gold' (17th May 2011)
- Wall Street Journal: Superweed Outbreak Triggers Arms Race (4th June 2010)
- Press releases
- External links
- Save our Crops Coalition: SOCC Opposes New Uses of Dicamba and Residue Tolerances for Monsanto's Dicamba Tolerant Crops (17th January 2013)
- CRIIGEN: Long-term toxicity study of GM herbicide-tolerant maize (September 2012)
- Genok: Report: Soybean Production in the Southern Cone of the Americas: Update on Land and Pesticide Use (July 2012)
- Friends of the Earth Europe: Herbicide resistant crops
- GeneWatch briefings