91av

GENETICALLY modified crops are now grown in more than 16 countries. In 2002, farmers around the world planted 60 million hectares of land with dozens of varieties of GM crops. Yet in the UK, the decision to approve or reject the technology could hinge on the results, out this week, of four-year trials involving 280 fields of three GM crops.

Although these farm-scale evaluations are being portrayed as a test of the environmental credentials of GM crops, it is really the weedkillers to which they are resistant that are on trial. The studies looked only at the effect that these herbicides had on “wildlife” in fields, in the form of weeds and insects. But if the aim of the exercise really is to save farmland wildlife, banning any of the GM crops tested is unlikely to make much difference.

That’s because herbicide use in the UK is soaring even before any GM crops are introduced. And in the long term, farmers denied GM crops may instead turn to non-GM crops bred to be resistant to herbicides. That might seem like a good thing to those who oppose GM technology, but like GM crops, the conventionally bred strains allow farmers to splash on the herbicide. Their impact on farmland wildlife in Europe could be worse than that of the weedkiller-resistant GM crops, because many allow the use of more noxious herbicides than GM strains. And as with GM crops, the herbicide-resistance could spread to other crops and wild relatives.

Despite this, these crops do not have to undergo the same scrutiny as GM crops because they are not genetically engineered. The only hurdle they face in the UK is tests designed to confirm that they are indeed new varieties. And while GM crops can be banned under world trade rules on the grounds that they pose a threat to human health or the environment, the same is not true of conventional herbicide-resistant crops.

“We’re as concerned about them as GM crops,” says Brian Johnson, an adviser on GM technology to the conservation group English Nature. “The same principles should be applied to all crops, irrespective of their origin.” The sequencing of plant genomes is making it much easier for breeders to create non-GM plants with a desired trait, he points out.

None of these crops is yet grown in the UK, unless one counts maize, which is naturally resistant to the herbicide atrazine. But one company has already tried to market them. An application to sell imidazolinone-resistant rapeseed in the UK was turned down in 1998 only because the strain proved low-yielding when trialled (91av, 27 February 1999, p 4). This strain and others like it are already grown in several countries (see Table). More are being developed. And companies are likely to redouble their efforts if GM herbicide-resistant crops are banned in Europe.

“We’re continually looking at GM and non-GM solutions. If the market is there, we’d explore all avenues,” a Syngenta spokesman told 91av.

“We would be foolish to turn our backs on the possibility that other methods of plant breeding could generate the same results without the transgenic approach,” says a Monsanto spokesman. “The regulatory systems effectively ignore all these other methods, and are driven by politics, not science. As things stand, a non-GM plant would bypass the arguments against GM.”

But so far Monsanto has been unable to create conventional crops resistant to glyphosate, the herbicide it sells as Roundup. Glyphosate is regarded as one of the most benign herbicides because it breaks down relatively rapidly. That is not true of many of the herbicides to which companies have been able to breed resistant crops.

For instance, almost all Australia’s oilseed rape now consists of strains bred to be resistant to broad-spectrum herbicides. The most popular, accounting for 72 per cent of the total grown, is “TT canola”, which tolerates the triazine herbicides, including atrazine, an older herbicide suspected of poisoning frogs and polluting rivers.

The original strains were created by researchers at the University of Guelph in Ontaria, Canada, who cross-bred commercial canolas with a weedy relative, Brassica rapa, which had evolved resistance to triazines. Another variety, “Clearfield” rapeseed, is resistant to the imidazolinone family of weedkillers. Scientists made it by chemically mutating rapeseed strains until they produced some strains resistant to the herbicide.

Both strains were approved without the fuss surrounding GM crops, despite arguments that imidazolinones and atrazine are worse for the environment than the herbicides such as glyphosate. “The two canolas that were classically bred have greater problems with persistence of herbicides and resistance than the GM ones do,” says Rick Roush, now of the University of California at Davis, who served for five years with Australia’s GM regulation body, the Office of the Gene Technology Regulator.

“Atrazine is probably the most problematic of these two herbicides, as it is mobile in water and frequently appears in groundwater and waterways,” says Chris Preston of the University of Adelaide. “Atrazine is persistent and in dry years may cause minor damage to subsequent wheat crops.”

Imidazolinones, meanwhile, can last so long in soil that it is impossible to grow a crop the following season. “Australians opposed to GM crops have totally ignored the fact that most of our canola is already herbicide tolerant, and have also ignored problems with currently used herbicides,” says Preston.

In the UK the use of atrazine has increased from 34,000 kilograms a year in 1992 to over 130,000 kg in 2002, mostly because more naturally resistant maize and sweetcorn is being grown. Atrazine was one of the “conventional” treatments against which GM glyphosate-resistant maize was evaluated in the UK’s farm-scale trials.

Critics say that glyphosate-resistant GM maize is bound to look good compared with atrazine, and that the comparison is irrelevant because of an impending European ban. But the UK has applied for an exemption from the ban for sweetcorn.

The EU ban does mean that TT Canola is unlikely to be grown in Europe. But Clearfield products are edging closer, with launch this year of imidazolinone-resistant sunflowers in Turkey, and the development of similar varieties for southern and eastern Europe. BASF, the company that makes Clearfield strains, has just launched imidazolinone-resistant wheat in Australia and may develop variants for the European market.

Even without herbicide-resistant crops, GM or otherwise, herbicide use has soared in the UK, with glyphosate use more than quadrupling in a decade (see Graphic). The biggest rise has been on farms, where farmers receive subsidies to reduce overproduction by temporarily leaving fields fallow, but keep these “set aside” fields free of weeds with glyphosate. Glyphosate use has also soared on cereals such as wheat and barley, to compensate for a side effect of a popular fungicide.

“There’s no strategic control over technologies used in the countryside,” says Johnson. “We have many well-meaning technologies, but not a means to regulate them.”