Environment

Concerned scientists urge action on Monsanto superweeds

The Union of Concerned Scientists (UCS) is calling for action to halt the devastation being caused by herbicide-resistant superweeds. The union, based in the United States, is urging Congress and the US Department of Agriculture to support farmers who want to use sustainable agro-ecological practices rather than dangerous chemicals.

The UCS has just released an animated video to help convey its message. It says the agro-giant Monsanto and its competitors are responsible for the rise of superweeds that have developed resistance to a herbicide that once kept them in check. Superweeds are a grim reality for farmers across the US, the UCS says.

The video, “Monsanto Supersizes Farmers’ Weed Problem – but Science Can Solve It”, depicts Monsanto’s Roundup Ready seed and herbicide system as a superhero with a fatal flaw.

“As more and more farmers used more and more Roundup, genes for glyphosate resistance began to spread in weed populations,” the UCS said.

In its 2013 briefing paper, “The Rise of Superweeds – and What to Do About It”, the UCS said superweeds had spread to more than 60 million acres of farmland in the US and were wreaking environmental and economic havoc.

The paper sets out the history:
• In the 1990s, Monsanto introduced a new line of seeds called Roundup Ready, which were genetically engineered to be immune to glyphosate, the active ingredient in the company’s patented herbicide, Roundup.
• Roundup Ready seeds were expensive, but were widely adopted because they made weed control easier. And because glyphosate is less toxic than other common herbicides, the Roundup Ready system was hailed as an environmental breakthrough.

“At present, more than 15 years after farmers began growing Roundup Ready crops, the most widely grown US commodity crops are glyphosate-resistant, and farmers douse at least 150 million acres with the herbicide every year,” the paper’s authors, Doug Gurian-Sherman and Margaret Mellon, stated. “As a result of this heavy use, weeds showing resistance to glyphosate began appearing in fields more than a decade ago – first as occasional interlopers, but eventually as large infestations.”

Because many farmers can no longer rely on glyphosate alone, overall herbicide use in the US – which Roundup was supposed to help reduce – has actually increased. A study in 2012 indicated that about 404 million pounds more pesticides were being used than if Roundup Ready crops had not been planted.

UCS herbicide-increaseEstimates of actual herbicide use on US soybeans and future rates forecast by weed scientists. (Adapted with permission from Mortensen et al., 2012.)

The Roundup system had seemed like a superhero to farmers looking for an effective, relatively non-toxic way to fight weeds and they adopted it enthusiastically, the UCS said. “For a while, the system did reduce farmers’ overall use of herbicides, but before they knew what had hit them, the weakness in Roundup Ready had transformed their weed problems into a national superweed crisis.”

According to the UCS, the growth of resistance to Roundup Ready was accelerated by three factors:
Monoculture. Growing the same crop on the same land year after year helps weeds to flourish.
Overreliance on a single herbicide. When farmers use Roundup exclusively, resistance develops more quickly.
Neglect of other weed control measures. The convenience of the Roundup Ready system encouraged farmers to abandon a range of practices that had been part of their weed control strategy.

According to the 2013 International Survey of Herbicide Resistant Weeds, 24 species of weed had become glyphosate-resistant. The worst cases were in the southeastern United States, where a reported 92 percent of cotton and soybean fields were infested as a result of Roundup Ready crops.

The now-resistant Palmer amaranth is a fast-growing weed that can reach eight feet in height, outcompeting soybeans or cotton; it develops a tough stem that can damage farm machinery and must sometimes be removed by hand, which is an expensive proposition. Resistant ragweeds, marestail, and water hemp are aggressive weeds that have been spreading through the Midwest and the Corn Belt and farmers in the Great Plains are confronting resistant populations of kochia, a weed adapted to drier climates.

horseweedsHerbicide-resistant marestail, also known as horseweed, which can grow to be six feet tall.

The pesticide and seed industry has responded to the superweed crisis by engineering a new generation of herbicide-resistant crops to tolerate older herbicides such as 2,4-D and dicamba in addition to glyphosate. These crops are awaiting approval from the USDA.

In its briefing paper, the UCS points to the new dangers:
• 2,4-D and dicamba belong to a chemical class that has been associated with increased rates of diseases, including non-Hodgkins lymphoma.
• They are highly toxic to broadleaf crops, including many of the most common fruit and vegetable crops.
• They are more prone to volatilization (air dispersal) than glyphosate, so their increased use is likely to harm neighbouring farms and uncultivated areas.

“On top of all these drawbacks is a more fundamental one,” the UCS said. “Weeds that developed glyphosate resistance can develop resistance to the new herbicides as well – and this has already begun to happen. When major weed species develop widespread multi-herbicide resistance, farmers will really be in a bind because there are no new herbicides coming over the horizon to save the day.”

The UCS is calling on people to take action and to urge their members of Congress to help find lasting solutions to farming challenges.

There is a real solution available, the UCS says. “We call it healthy farms. It’s grounded in science, it’s sustainable, and it’s cost-effective; and more and more farmers are putting it into practice. The transition isn’t easy, however, and farmers need new policies and more research to help them make it happen.”

According to the UCS, farmers can control weeds using practices grounded in the science of agro-ecology, which works with nature rather than against it. These practices include crop rotation, cover crops, judicious tillage, the use of manure and compost instead of synthetic fertilizers, and taking advantage of the weed-suppressing chemicals that some crops produce.

“Such practices have benefits beyond weed control: they increase soil fertility and water-holding capacity, reduce water pollution and global warming emissions, and make the farm and its surroundings more welcoming to pollinators and other beneficial organisms.”

Recent research shows that agro-ecological practices work, the UCS says. “They make farms healthier, sustainable, and cost-effective, but change is being blocked by farm policies and research agendas that favour monoculture and by a lack of information and technical support for farmers who want to change their methods.”

The UCS wants Congress and the USDA to take a series of actions:

• Fund and implement the Conservation Stewardship Programme, which provides support for farmers using sustainable weed control methods.
• Institute new regional programmes that encourage farmers to address weed problems through sustainable techniques.
• Support organic farmers and those who want to transition to organic farming with research, certification, cost-sharing, and marketing programmes. (Organic farming serves as a “test kitchen” for integrated weed management practices that can be broadly applied to conventional farm systems.)
• Support multidisciplinary research on integrated weed management strategies and educate farmers in their use.
• Bring together scientists, industry, farmers, and public interest groups to formulate plans preventing or containing the development of herbicide-resistant weeds, and make the approval of new herbicide-tolerant crops conditional on the implementation of such plans.
• Fund and carry out long-term research to breed crop varieties and cover crops that compete with and control weeds more effectively.

Briefing paper: “The Rise of Superweeds—and What to Do About It”

The video “Monsanto Supersizes Farmers’ Weed Problem – but Science Can Solve It” was created by UCS member Nathan Shields of Draw4.Us.

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