The results of U.K. Government-commissioned research into the impacts of genetically modified herbicide tolerant (GMHT) cropping systems on weed seedbanks are published today.

The research was carried out for Defra by a team led by the Centre for Ecology and Hydrology and was an extension of the Farm Scale Evaluations - a four-year programme to study any effects the management of GMHT crops might have on the diversity and abundance of farmland wildlife, compared with the effects of weed control measures for the equivalent non-GM crops.

The results for the Farm Scale Evaluations of herbicide tolerant GM maize, beet and spring oilseed rape were published in 2003, and for winter oilseed rape in March 2005. They showed that growing GMHT crops can affect biodiversity, not because of the way the crops are bred but because of the different herbicides that are used with them.

Decisions on whether to permit the growing of GM crops in Europe now include an assessment of the impact of management of those crops on biodiversity, and the results of the Farm Scale Evaluations will inform the Government's decisions on any proposals to cultivate GMHT beet, maize and oilseed rape anywhere in the European Union using the methods trialled.

The new research published today in the Royal Society's journal Biology Letters considered longer-term effects by collecting data on weed seedbanks in the fields used for the Farm Scale Evaluations for the following two years of conventional crops. It investigated whether the effects observed during the Farm Scale Evaluations carried on when farmers returned to their normal farming practices.

The research found that:

• The weed seedbank was lower in the fields where herbicide-tolerant GM spring oilseed rape had been trialled (compared to non-GM spring oilseed rape). This effect persisted for two years. Results for GM winter oilseed rape published in March 2005 showed the number of weeds were similar, but in the GM crop there were fewer broad leaved weeds and more grass weeds;
• The weed seedbank was higher in the fields where herbicide-tolerant GM maize had been trialled (compared to non-GM maize). This effect persisted for two years;
• The weed seedbank in the fields where GM beet had been trialled was lower in the first year after the Farm Scale Evaluations, but this effect had largely disappeared by the second year.

The Government welcomes the publication of this report. It provides important information on the impact of GM crops on weed populations and adds to the UK's considerable scientific knowledge bank on GM crops, amongst the largest of its kind in the world.

The Government is committed to sound science as its basis for decisions on GMs, with protection of human health and the environment as its top priorities. On the basis of current evidence, no GM crops have been approved for commercial cultivation in the UK to date.

The full report can be viewed at http://www.journals.royalsoc.ac.uk. 
For further information visit http://defra.gov.uk/environment/gm/research/epg-cpec28.htm

BACKGROUND

1. The Government set out its policy on the commercial cultivation of GM crops in a statement to Parliament in March 2004. The Government has concluded that there is no scientific case for a blanket ban on the cultivation of GM crops in the UK, but that proposed uses need to be assessed for safety on a case-by-case basis.

2. A non-technical summary of the main findings for all four crops tested in the FSE was published on 21 March 2005. A pdf of this document in Adobe Acrobat format is available to download (430 KB).

3. Further information and results:
* 2005: results for winter oilseed rape (published on 21st March 2005)
* 2003: results for maize, beet and spring oilseed rape (published 16th October 2003)
* Raw data from the FSEs: The raw data from the FSEs are available at www.farmscale.org.uk