Greener light on GM crops

A new study of a number of specific GM crops over several years in rotation with conventional crops has found no evidence that they may be more harmful to the environment, in terms of the reservoir of weed seeds important for much wildlife, than conventional varieties alone. The findings of the Botanical and Rotational Implications of Genetically Modified Herbicide Tolerance (Bright) project in the UK studied sugar beet and winter oilseed rape which had been engineered to make them tolerant of specific herbicides. The novel crops were grown in rotation with non-GM cereals, and compared with similar rotations involving non-GM beet and rape. The project concluded that the GM varieties used in this way did not necessarily deplete the soil of weed seeds. The results have been released a year after another major GM investigation in the UK, called the Farm-Scale Evaluations or FSEs. Both these studies have been part of a far more cautious approach to the introduction of such crops in Europe, compared with the US and other regions. The FSEs found that two GM varieties, a sugar beet and a spring rape, were more damaging to biodiversity than conventional crops. There were fewer insect groups, such as bees and butterflies recorded among the plants. A GM maize, on the other hand, appeared to be less damaging than its conventional cousin. There were more weeds in and around the biotech maize crops, more butterflies and bees around at certain times of year, and more weed seeds. The British government cautiously opened the way to cultivation of this crop but Bayer CropScience, the company involved, said that government conditions failed fully to endorse planting the crop because of the length of time needed to begin production. A spokesperson for the company said that it was unlikely to get commercialisation of the product before 2006 or 2007. “This makes an already ageing variety old and essentially economically unviable,” he said. He said the company was concerned that the decision had been influenced by calls for new legislation on guidelines for farmers, a legal framework for liability, further biodiversity trials and rewrites on present and future EU licences for the technology. But Elliot Morley, the British environment minister, defended the government’s stance. “We do not apologise for the fact there is a tough EU-wide regulatory regime on GMs. It applies to the whole of the EU and not just the UK.” The British government’s stance, and that of other regulatory bodies, provides a tough backdrop for commercialisation of the crops in Europe. FSEs were considerably larger in scale than the Bright project, involving 60–70 fields across the UK. The Bright project focused on smaller plots but also at sites around the UK. The FSEs were a straight comparison of GM versus nonGM in each growing season over a few years, whereas the Bright project aimed to reflect normal farming practices in each location, indicating how GM varieties might perform if they were integrated into UK agriculture. Jeremy Sweet, the Bright project’s scientific co-ordinator, believes that in both studies, the impact on weed seeds is down to the herbicides used, rather than the GM crops themselves. “The critical thing is how the herbicides are used on these crops: so what we need to do is to ask whether these herbicides have the potential to do more harm than the current ones.” Sweet concludes that the herbicides used with the GM varieties can be less harmful than those used on the conventional crops. “One of the interesting things about the herbicide-tolerant systems is that you can apply the herbicides later, when you have got a much better idea of what spectrum of weeds is in the field, and therefore you can target your weed control more effectively. “This means that you have some scope for manipulating populations of weeds so that if you do want to retain a reasonable weed flora in the field, you can do that. “You can also control the weeds which are competing with the crop, particularly when the crop is being established.” “The most important element of the Bright project is the fact that it confirms comments made in the FSEs about the importance of management,” says Chris Pollack, who chaired the FSE trials but was not involved in the Bright project. “You can use management to generate rotations that give you the best balance between weed control and preservation of the seed supply.” The Bright project did, however, show some potential problems with cross-breeding between herbicide-tolerant varieties of rape, producing seeds immune to more than one herbicide. News focus