Super-weeds are not lurking round the corner of every GM plantation

CropGen's Professor Howard Slater

Environmentalists have argued that GM crops might crossbreed with wild plants, producing more weedy offspring. But the Imperial College team found that native wild plants displaced both GM and ordinary crops and that the GM crops were actually outlived by the conventional ones.

Reporting their findings in the science journal Nature, the researchers said most of the crops died out after four years, and after 10 years the only survivor was one type of non-GM potato.

'No surprise'

When the study began, the kinds of GM plants available were varieties engineered to make them better able to withstand spraying with herbicides or insect attack.

One of the report's authors, Rosemary Hails, told BBC News Online that the results came as no surprise, as such traits were unlikely to help a plant survive in the wild.

Protesters fear GM crops could turn into super-weeds

"We wouldn't expect herbicide tolerance to give a plant an ecological advantage," she said.

The report's authors stress that they only looked at specific kinds of GM crop and did not look at new crops engineered to withstand drought or natural pests.

"Our results do not mean that other genetic modifications could not increase weediness or invasiveness of crop plants, but they do indicate that arable crops are unlikely to survive for long outside cultivation," they wrote in Nature.

"We will always have to be careful about managing crops and about spraying regimes to ensure that we don't end up with varieties in places we don't want them," Dr Hails added.

Industry welcome

The scientific group CropGen, which is backed by the crop industry, welcomed the study.

"These results confirm what many plant geneticists and ecologists have long expected: that super-weeds are not lurking round the corner of every GM plantation," CropGen's Professor Howard Slater said.

The research provides no guarantee that GM super-weeds will not establish themselves in the wider environment

Adrian Bebb, Friends of the Earth

The environmental group Friends of the Earth (FoE) also welcomed the study's findings.

Adrian Bebb, food campaigner at FoE, said: "They add to our knowledge on the survival of crops in the wild.

"However, the research provides no guarantee that GM super-weeds will not establish themselves in the wider environment.

"This risk will increase significantly if the government succeeds with its plans to conduct GM trials at over 90 sites throughout the UK," he added.