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GE Crops Need More, Not Less, Herbicides

Dear Friends and Colleagues,

The GM industry has always claimed that the advantage of herbicide-tolerant
(HT) GM crops is that they lead to reduced herbicide use.

This is supposedly because as a GM crop grows, a farmer can spray the company's wide-spectrum herbicide that will kill all weeds but not the GM crop. Farmers can use just one type of herbicide rather than a mixture of herbicides. This would supposedly be better environmentally, and cheaper for the farmer.

But an examination of data from the US Department of Agriculture, shows that GM crops have led to increasing amounts of herbicide use over the years. Although the number of different types of herbicide used on a GM farm has reduced, the overall volume of herbicide has on average increased by 50 million pounds (weight) per year in the US.

A recent report from the Northwest Science and Environmental Policy Center confirms what many critics of GM have been saying for years. Wide-spectrum herbicides (in the US, Monsanto's glyphosate, or "Roundup" is the most
common) lead to "Superweeds". Superweeds can arise through a number of
ways: through selection pressure on weed populations; gene transfer from GM crops to wild relatives; or through "volunteers" of the crop appearing unwanted in following years. These weeds can therefore only be killed through increased dosages or by mixing in stronger herbicides. Thus the long-term effectiveness of herbicide-tolerant crops will always be limited.

It is possible that GM farmers are less aware of these facts because the increases in use have been incremental. In fact, for the first 2 to 3 years, herbicide use does decrease, and thus pleases farmers. But in the years following, the need for herbicide usage increases substantially. The effects of this has been hidden from the farmer because the cost of glyphosate has gone down over the years.

GM crops have been grown in the US for 8 years now, and so we can finally have a longer-term review of the effects and effectiveness of herbicide-tolerant crops. The results show that long-term, GM creates more problems than it solves.

Please visit
To download "Impacts of Genetically Engineered Crops on Pesticide Use in the United States: The First Eight Years".

Best wishes,


1. Genetically Engineered Crops Now Increasing Pesticide Use in the United States
Press Release from the Northwest Science and Environmental Policy Centre (US).
Date: 25 November 2003
Dr Charles Benbrook
2. GM Crops - Trait Information: Herbicide Tolerance
Web page from Gene Watch. Date: Sept 2002
3. Roundup Ready Soybeans
Case Study from the Union of Concerned Scientists.
4. GM Crops May Become Weedier
Press Release from English Nature. Date: 5 February 2002
5. Glyphosate Resistance is Showing a Worldwide Rise
Article in Farmers Weekly (UK). Date: 23 November 2001

1. Genetically Engineered Crops Now Increasing Pesticide Use in the United States

Press Release from the Northwest Science and Environmental Policy Centre (US).
Date: 25 November 2003
Dr Charles Benbrook

The planting of 550 million acres of genetically engineered (GE) corn, soybeans and cotton in the United States since 1996 has increased pesticide use by about 50 million pounds, according to a report released today by the Northwest Science and Environmental Policy Center.

The report is the first comprehensive study of the impacts of all major commercial GE crops on pesticide use in the United States over the first eight years of commercial use, 1996-2003. It draws on official U.S. Department of Agriculture data on pesticide use by crop and state. The report is entitled "Impacts of Genetically Engineered Crops on Pesticide Use in the United States: The First Eight Years," and is the sixth in a series of "Technical Papers" prepared for Ag BioTech InfoNet.

It is being published today via the Internet (hard copies will not be provided, but can be printed for free from the website). The report calculates the difference between the average pounds of pesticides applied on acres planted to GE crops compared to the pounds applied to otherwise similar conventional crops. In their first three years of commercial sales (1996-1998), GE crops reduced pesticide use by about 25.4 million pounds, but in the last three years (2001-2003), over 73 million more pounds of pesticides were applied on GE acres.

Substantial increases in herbicide use on "Herbicide Tolerant" (HT) crops, especially soybeans, accounted for the increase in pesticide use on GE acres compared to acres planted to conventional plant varieties. Many farmers have had to spray incrementally more herbicides on GE acres in order to keep up with shifts in weeds toward tougher-to-control species, coupled with the emergence of genetic resistance in certain weed populations.

"For years weed scientists have warned that heavy reliance on herbicide tolerant crops would trigger ecological changes in farm fields that would incrementally erode the technology's effectiveness. It now appears that this process began in 2001 in the United States in the case of herbicide tolerant crops," according to Benbrook.

The report concludes that the other major category of GE crops, corn and cotton engineered to produce the natural insecticide Bacillus thuringiensis
(Bt) in plant cells, continues to reduce insecticide use by 2 million to 2.5 million pounds annually. The increase in herbicide use on HT crop acres, however, far exceeds the modest reductions in insecticide use on acres planted to Bt crops, especially since 2001.

The 46-page report is posted on Ag BioTech InfoNet at --

Dr. Benbrook has a PhD. in agricultural economics and has carried out several studies on the impacts of genetically engineered crops on farming systems and costs and the environment. He directs the Northwest Science and Environmental Policy Center, which is based in Sandpoint, Idaho. From 1984 through 1990, he served as the Executive Director of the National Academy of Sciences Board on Agriculture.

For More Information:
Contact Dr. Benbrook at 208-263-5236 or via e-mail:

Financial and in-kind support for this study was provided by: The Union of Concerned Scientists; The Leopold Center for Sustainable Agriculture, Iowa State University; Consumer Policy Institute, Consumers Union; The Center for Food Safety; Institute for Agriculture and Trade Policy; and The Organic Farming Research Foundation.


2. GM Crops - Trait Information: Herbicide Tolerance

Web page from Gene Watch. Date: Sept 2002

Making a crop tolerant to a certain herbicide (weed killer) allows the farmer to spray the crop with that herbicide, killing the weeds but leaving the crop undamaged. This makes management of the crops easier and should allow a farmer to use one broad spectrum herbicide rather than several different ones.

Potential Benefits


Easier weed control and increased profits through lower labour requirements.

Less herbicide use by reducing the number of applications and total amount (by weight or volume) of herbicide used.

Increased yields through better weed management and, therefore, increased profits.
* Less environmentally damaging herbicides to replace more toxic,
persistent chemicals.

Potential Dangers


Gene transfer to related wild species may take place, creating herbicide tolerant Œsuper weeds¹. This depends on the proximity of species with which the crop can successfully hybridise.

The crop itself may become a problem weed, either by spreading from the field or when seed shed at harvest emerges in the following crop (so-called Œvolunteer¹ weeds). This is considered inevitable by many weed specialists.

The increased use of the specific herbicide a crop is made tolerant to, will encourage the emergence of resistant weeds through selection pressure.

Neighbouring organic or non-GM crops may be pollinated by the GM crop, leading to genetic contamination with the foreign genes. Levels of acceptable contamination have not been set and organic farming standards are likely to demand zero levels.

The widespread use of broad spectrum herbicides (like glufosinate or
glyphosate) will lead to fields being efficiently cleared of weeds, thus removing some of the remaining food sources for farmland birds and other wildlife. The use of pesticides and herbicides is already thought to have contributed to the dramatic decline in farmland bird species in the UK.
* Herbicide use patterns will change and although amounts may be reduced
overall in terms of weight and volume (in large part because broad spectrum herbicides are more potent), the use of the specific herbicides that crops are being made resistant to will increase dramatically.


3. Roundup Ready Soybeans

Case Study from the Union of Concerned Scientists.

Herbicide-tolerant crops are engineered to enable crops to withstand doses of herbicides that would otherwise kill them. These crops are generally developed by the manufacturers of the herbicide with the hope of increasing the sale of that herbicide. Roundup ReadyTM crops, for example, are produced by the Monsanto company, the producer of the herbicide Roundup, a billion-dollar product that generates about 40 percent of the company's annual revenue. The projected planting of perhaps 12 million acres of Roundup ReadyTM soybeans will substantially increase Monsanto's revenues as farmers switch from their current herbicide to Roundup.

What do these crops mean for the environment? The environmental benefit Monsanto claims for Roundup ReadyTM soybeans is associated with the move away from popular herbicides like atrazine, whose active ingredients persist in the environment. Even granting that glyphosate is less toxic than atrazine and generally to be preferred to it, a switch from one herbicide to another does not result in an environmentally sound agriculture.

Glyphosate is highly toxic to plants and fish. Few who care about the environment welcome the annual dousing of 12 million acres of American farmland with such a chemical. In addition, many preparations of glyphosate are dissolved in so-called inert ingredients that can also be toxic. More fundamentally, it is highly unlikely that chemical companies that produce herbicide-tolerant plants will ever develop products that cut into their substantial herbicide revenues. Thus, to the extent that Roundup ReadyTM products are environmentally beneficial, this is likely to be the limit of progress in that direction. The bottom line: US agriculture remains shackled to intensive chemical use.

Moreover, use of glyphosate-tolerant soybeans poses environmental risks. Herbicide-tolerant crops can transfer their tolerance trait to nearby related plants and weeds. While there are no such relatives in the United States, they do exist in other parts of the world, where the resulting glyphosate-resistant weeds will make weed control much more difficult. In the United States, the use of glyphosate on millions of acres will intensify the selection pressure for resistance in weeds unrelated to soybeans. As weeds become resistant, farmers will have to use more glyphosate, accelerating the downward spiral toward the loss of glyphosate as a weed-control tool. In addition, the glyphosate-tolerant plants could have effects on soil ecology that have not been assessed.

Are there alternative approaches to weed control other than intensive, prophylactic herbicide use? Yes, there are new tillage methods, multiyear crop rotations, cover crops, and other techniques of biointensive weed management. Scientists also urge farmers to accept of levels of weeds that may give their fields a messy appearance but have no economic impacts.

4. GM Crops May Become Weedier

Press Release from English Nature. Date: 5 February 2002
An extensive study commissioned by English Nature* of GM herbicide tolerant oilseed rape crops in Canada has revealed that genes from separate GM varieties can accumulate ('gene stacking') in plants that grow from seed spilled at harvest (volunteer plants). This happens because different varieties cross-pollinate, and their offspring may contain the accumulated genes from GM varieties with different genetic traits. In Canada these plants are now resistant to several widely used herbicides, with farmers regularly resorting to old herbicides to control them. In effect they are on the road to becoming nuisance weeds.

The Canadian system of voluntary guidelines advising farmers to leave a separation distance of 175 m between different GM varieties seems to have broken down, and 'gene stacking' is now widespread in Canada. A code of practice for farmers growing GM crops in the UK has already been developed by the industry body SCIMAC.

Dr Brian Johnson, English Nature's biotechnology advisor said today: "Our report shows that the SCIMAC code is probably inadequate to prevent gene stacking happening in Britain, if these crops were commercialised. The consequences for farmers could be that volunteer crops would be harder to control and they might have to use different, and more environmentally damaging, herbicides to control them."

English Nature are concerned that attempts to eliminate GM volunteers with multiple herbicide tolerance in 'weedy' crops like oilseed rape could lead to more intensive herbicide use in field margins and uncropped habitats, which can be important refuges for wildlife.

Dr Johnson said: "We do not yet know how 'stacked gene' plants would behave either in farmers' fields or in the wild. The European regulatory system has not yet approved GM herbicide tolerant oilseeds for general release. English Nature will be working with DEFRA and ACRE to ensure that risks from possible gene stacking are properly addressed, and that we avoid the mistakes that have been made in Canada".

The European Commission has recently proposed that a threshold of up to 0.7% GM seed should be allowed in batches of conventional crop seed. English Nature are deeply concerned that if this proposal were to be adopted, it might be a recipe for gene stacking, because the GM plants from a seed batch could be made up of several varieties that would inevitably hybridise, giving 'volunteer' plants next season with multiple GM traits. It will be difficult to police seed batches to ensure that this does not happen.

English Nature has been pressing the GM industry to explain how to deal with these issues before GM crops are released widely, rather than wait for stacking to emerge and then try to control the rogue crop plants.
Notes for editors

1. * On this issue, English Nature is the lead agency for the UK
statutory nature conservation agencies which are English Nature, Scottish Natural Heritage, The Countryside Council for Wales and the Joint Nature Conservation Committee.
2. The study, Gene-stacking in herbicide-tolerant oilseed rape: lessons
from the North American experience, English Nature research report Number 443, was undertaken by Jim Orson, director of Morley Research Centre, on behalf of English Nature. Embaroged copies are available from English Nature¹s national Press Office and will be on the web site on 5 February 2002.
* ŒVolunteer¹ crop plants are those that grow from seed left on the
ground after harvest. They germinate and (unless they are controlled by cultivation and herbicides) can appear in following crops, field margins and roadside verges.
* Gene stacking is where cross-pollination results in genes from
different GM varieties occurring together in individual 'volunteer' plants that grow from seed left behind during harvesting. Some volunteer oilseed rape (canola) plants in Canada have three herbicide tolerance genes within them, making them resistant to some of the most commonly used agricultural herbicides.
* ACRE is the Advisory Committee on Releases to the Environment. ACRE is
an independent committee that advises ministers on whether consent should be given to release GMOs into the environment.
* SCIMAC is the Supply Chain Initiative for Modified Agricultural Crops,
an industry sponsored group that has produced guidelines for growers intending to use GM crops.
4. The SCIMAC Code of Practice, published in 1999, recommends a
separation distance of 50m for GM oilseed rape.
5. A copy of the EC working paper on adventitious presence of GM seeds in
seed of conventional plant varieties is available at The opinion of the EC Scientific Committee on Plants, which advises the Commission, is that the proposed thresholds of GM presence in non-GM seed will be difficult, if not impossible, to achieve, particularly as the global area of GM crops continues to grow. The opinion is published at

For more information: English Nature's National Press Office 01733 455190 out-of-hours 07970 098005 email or visit our website at

5. Glyphosate Resistance is Showing a Worldwide Rise

Article in Farmers Weekly (UK). Date: 23 November 2001

New Products, new advice and new problems were debated in detail at last week's International "Weeds Conference" staged by the British Crop Protection Council in Brighton. Over the following four pages Charles Abel, Andrew Blake and Andrew Swallow report the highlights

Resistance to glyphosate (Roundup) is emerging all around the world, potentially jeopardising the 2.5 billion dollar market for genetically modified herbicide tolerant crops.

The latest discovery is glyphosate resistant ryegrass in South African vineyards where growers have used Roundup for 23 years.

"Monsanto is very sensitive because half the soya and maize is in GM herbicide tolerant varieties, creating a market worth $2.5b," said Andrew Cairns, of Natal University, Pietermaitzburg.

Resistance has also been found in ryegrass in New South Wales and Western Australia, a grass-weed in Malaysia, a broad-leaved weed in Delaware and ryegrass in California. In one US case, the repeat use of Roundup in GM herbicide tolerant maize has been blamed for the development of resistant weeds.

"I agree with the technology, it's a very good idea," said Prof Cairns. "But they need to have the stewardship in place to prevent this becoming a bigger issue."

Resistance problems are predicted to increase but a simple change in herbicide use should offer a solution, said Michael Owen of Iowa State University.

"I don't see that the shifts on establishment of resistant populations is going to be a big issue." Using an alternative mode of action should solve the problem, although the number of new modes of action becoming available is decreasing, he said.

Over-use of glyphosate by growers is to blame for the rapid development of resistance in common waterhemp and horseweed. One or two applications would often be enough to give economic control, but growers frequently use three or even four applications to keep fields cosmetically clean, said Mr Owen.

That puts a strong selection pressure on the weed population. In one case in the eastern corn belt, horseweed became resistant to glyphosate after just three years of growing glyphosate tolerant crops. A desire to show spotlessly clean fields to non-farming landlords adds to the problem, he said.

"Growers do not look at the economics of weed escapes. They view GM crops as an excellent chance to go out late season with the sprayer just to clean the crop up. This aesthetic weed management is a real problem for us."