London (July 26th, 2005) – The UK’s GM “hype”rmarket yesterday re-opened for business.

The new product on offer was a report (ref. 1) that genes from genetically modified, herbicide-tolerant oilseed rape had been found in charlock, a related wild crucifer species. Potentially this might give a competitive advantage to the recipients not possessed by the native plants.

Interestingly – and unusually – the paper itself begins with a comment from the reviewers, remarks worth quoting in full:

Although this study identified hybridisation between oil seed rape and Sinapis arvensis, such a finding needs to be interpreted with caution. The frequency of such an event in the field is likely to be very low, as highlighted by the fact it has never been detected in numerous previous assessments. Furthermore, the conditions where the hybrid was found appear to be quite unusual, restricted as it was to a case where Sinapis was sufficiently abundant in a crop to act as a significant conspecific pollen donor. The consequences of the transfer of the herbicide tolerance trait on the fitness and persistence of Sinapis arvensis were not assessed in this study but are presumed to be negligible. Nevertheless, this unusual occurrence merits further study in order to adequately assess any potential risk of gene transfer.

What happened was a very rare event of cross-pollination from GM rape, unusual indeed because it had not been observed during the several years of use of this plant in field trials. The reviewers are clearly correct: not only is the frequency likely to be low, it is low. One out of a total of almost 100,000 charlock plants tested had acquired the GM trait; that individual produced eight seeds, all of them sterile. Crosses between related plants are, of course, not unknown in the wild and one must pay tribute to the management of the GM oilseed rape trials that the frequency of crossing was so minimal.

Dr Les Firbank, co-ordinator of the farm-scale evaluations of GM crops at the Centre for Ecology and Hydrology (where this latest research was done), said the impact of the GM resistant weed would be "pretty much non-existent". "It's recognised that gene flow from GM crops to wild relatives is a potential problem, but in this case it happens very, very rarely and there are no environmental consequences," he said.

"Some people would say any gene flow at all is unacceptable. I personally think the risk is low enough to be acceptable." (ref. 2)

Elliot Morley, the UK Environment Minister with responsibility, rejected an allegation that the Government was acting as a ‘cheerleader’ for GM crops. Commenting on the cross-pollination report, he said: “No-one can state conclusively that GM technology is either wholly good or wholly bad. Government does not promote GMs - our duty as regulators is to ensure that the decisions we take are precautionary and strictly evidence-based. We take the only sensible approach, to assess each crop on a case-by-case basis”.

“Contrary to some media reports, the so-called hybrid has not been confirmed by researchers as a cross between oil seed rape and charlock, but is a finding we cannot ignore."

"A year later when researchers revisited the site where the possible hybrid plant had been found, and took seeds from the plants growing there, they found no evidence of gene transfer. So even if a hybrid did once exist it has disappeared. We do however need to improve our understanding of all aspects of gene transfer and this means we must take this into account with individual GM applications” (ref. 3).

The notion that hybrids between GM crops and weeds will lead to the emergence of uncontrollable “superweeds” is an exaggeration typical of the campaigning groups. Even if the herbicide resistance genes were acquired by a few individuals weeds, farmers could still managed them, just as they already manage refractory weeds.

By contrast with the campaigning approach, take a look at the BBC website (ref. 4) for an admirably balanced view of the whole episode.


1. Roger Daniels, Caroline Boffey, Rebecca Mogg, Joanna Bond & Ralph Clarke (July 2005). The potential for dispersal of herbicide tolerance genes from genetically-modified, herbicide-tolerant oilseed rape crops to wild relatives. ( gm/research/pdf/epg_1-5-151.pdf)

2. Ian Johnston (26 July 2005). Green body's fury at 'superweed' in field of GM crops. The Scotsman (

3. Superweed stories 'wildly irresponsible' – Morley. Department for Environment, Food and Rural Affairs (25 July 2005) (

4. Scientists play down 'superweed'. BBC News (25 July 2005) (


  “Super” hyperbole strikes again