Andreas Späth

The superweeds cometh

2010-06-02 07:50

“It won’t happen, because it can’t happen.” That, in a nutshell, has always been the response of biotechnology companies like Monsanto whenever critics have suggested that the widespread introduction of pesticide-resistant genetically modified crops will inevitably lead to the emergence of pesticide-resistant weeds, dubbed superweeds. Well, guess what? They’re here!

The first weed that could stand up to glyphosate, the main ingredient in Monsanto’s best-selling “broad spectrum” herbicide Roundup, made its appearance in a Delaware soybean field in 2000. Today, a further ten Roundup-resistant species have been reported in fields planted with genetically modified cotton, soy and maize in 22 US states and further afield in Argentina and Brazil.

In parts of the US South, including Georgia, Arkansas, North and South Carolina, Tennessee, Missouri and Kentucky, soybean fields have been infested with a virulent strain of Roundup-resistant pigweed, which has been described as the perfect superweed. It grows to a height of three metres at a rate of more than an inch a day, is drought hardy, produces 10 000 seeds at a time and happily smothers young soy seedlings.

The rationale behind herbicide-resistant crop plants is simple enough. A farmer who’s planted so-called Roundup Ready cotton, for instance, simply douses his entire field with Roundup which will kill every plant it comes in contact with other than the cotton itself, saving the farmer time and increasing his productivity. For Monsanto, who supply the proprietary genetically-modified cotton seeds along with the Roundup every season, it’s a very profitable arrangement. Even the environment is supposed to benefit since farmers are theoretically expected to require less herbicide.

In reality, of course, things aren’t quite that simple. As early as the 90s, opponents of genetically engineered crops suggested that herbicide-resistant plants would pass on their special genetically-engineered traits to closely related weeds by cross-breeding and hybridisation. Others argued that the extensive use of a single chemical for weed control was bound to result in the evolution of superweeds. According to journalist and author Michael Pollan, “the theory of natural selection predicts that resistance will appear whenever you attempt to eradicate a pest […] using such a heavy-handed approach”.

With the large-scale introduction of herbicide-resistant crops, sales of glyphosate in the USA alone sky-rocketed by a factor of 15 between 1994 and 2005 and sure enough superweeds started to proliferate gradually and in tandem. In response to the appearance of ever-hardier weeds, farmers found themselves needing to apply extra lashings of glyphosate and eventually resorted to additional, more potent weedkillers as well, landing themselves in a herbicide treadmill and reversing the intended trend of reduced chemical use.

All of this is rather ominous for us here in South Africa. While we weren’t among the earliest adopters of genetically-modified crops, local agriculture along with the government have enthusiastically embraced the technology in recent years. South Africa remains the only country to have allowed the large-scale commercial cultivation of a genetically modified crop that is also one of its staple foods. Many of the mielie fields in this country are planted with herbicide-resistant genetically modified maize. So don’t be surprised if stories about pernicious superweeds start to rear their ugly heads in due course.

What are the alternatives? A return to conventional crops, seasonal crop rotation and weed control using a combination of different herbicides and mechanical cultivation techniques such as regular ploughing. Or, much better yet, a courageous move to organic agriculture with weed and pest control through natural, sustainable and environmentally-friendly methods. “That won’t happen, because it can’t happen”, the biotech multinationals tell us. “We need genetically modified crops to feed the world’s growing population”, they insist. Perhaps it’s time we stopped listening to them.

- Andreas manages Lobby Books, the independent book shop at Idasa’s Cape Town Democracy Centre.

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