Genetic Food: The Case Against, Fields where birds don't sing

YOU MAY never have heard of Green Concrete, but that's the idea behind much of the opposition to genetically modified food plants. It means a field devoid of all wildlife - insects, wildflowers, birds or animals - a field that is full of genetically engineered crops, but otherwise sterile.

It's what the Government's own environmental scientists fear Britain's farmland may turn into, once it is filled with new plants, which are being genetically engineered to be tolerant of a new generation of extremely powerful weedkillers.

This is the purpose of the vast majority of the hundreds of GM crops currently on trial in Britain. Get it straight: these are not tomatoes modified to taste sweeter or last longer.

They are nearly all oilseed rape, sugar beet and soybeans, which have been engineered by one of the big biotech companies such as Monsanto, Zeneca or AgrEvo, to be tolerant of just one individual new weedkiller which that company itself produces. These weedkillers - Monsanto's Roundup is the best known - are "broad spectrum" herbicides that, directly or indirectly, will kill everything in the field but the crops themselves.

The companies claim that less of them can be used, and so they are environmentally friendly, but the argument is disingenuous as it confuses dosage with impact: the first might be less but the second is certainly greater.

The prospect of their widespread use is alarming to anyone who has watched the catastrophic decline, because of intensive farming practices, of once- familiar farmland birds such as the skylark, the partridge and the corn bunting. And it is the reason for the remarkable call from the Government's own wildlife adviser, English Nature, and its sister agencies in Wales and Scotland, for a three-year moratorium on the commercial growing of GM crops until a proper assessment is made of the effects on wildlife of the deadly new herbicides they come with.

Neither English Nature nor any other government body has called for a moratorium on the consumption of GM food but the call for a delay in commercial crop planting has been misinterpreted, not least by the Tory leader, William Hague, in questioning Tony Blair a fortnight ago.

While the food issue is more emotive with the public - why should we trust your assurances that a new and untried foodstuff is safe when you misled us over BSE? - it is the Green Concrete argument that has the solid scientific backing.