Today Defra published a report that gives a better understanding of the potential impact of GM herbicide tolerant crops on farming practices and the environment. It looks in particular at how farmers might deal with ‘volunteer' weeds that are herbicide tolerant.

The study does not suggest that weeds might be created that could not be controlled. It says that, depending on the circumstances, farmers may need to change their normal practices to ensure they don't get a weed problem. The report considers a number of possible changes farmers might implement to manage herbicide tolerant weeds, such as using a different herbicide.

The research only relates to weeds in crop fields. Evidence already shows these crops are unlikely to create a problem outside of arable fields, because the herbicide tolerance trait would not give wild plants in unmanaged areas any competitive advantage.

The Advisory Committee on Releases to the Environment has considered this research and said that:

• it adds to our understanding of possible long-term effects that could be associated with GM herbicide tolerant crops; however, this was a desk study and the scenarios examined may not be representative of the field situation; 

• monitoring for changes in cropping practices and management after herbicide tolerant crops are grown would be appropriate to address the issues raised by this research;

• the work demonstrates that the management associated with different crops and different herbicide tolerance traits have different effects, and ACRE will therefore continue to address these issues on a case-by-case basis.

BACKGROUND

1. The report ‘Agronomic and environmental implications of the establishment of GM herbicide tolerant problem weeds' is available on the Defra website.

2. The advice of the Advisory Committee on Releases to the Environment (ACRE) on the implications of this research is available in full at www.defra.gov.uk/environment/acre/advice/pdf/acre_advice78.pdf (42 KB)

3. ‘Volunteers' are plants that develop from seed shed during harvest. They are regarded as weeds in succeeding crops, and farmers normally control them by applying suitable herbicides.

4. There are no current plans to cultivate GM herbicide-tolerant crops in the UK. Varieties of GM herbicide tolerant beet, oilseed rape and maize were previously grown in the Defra-funded Farm Scale Evaluation trials. These studied the impact on farmland biodiversity of the novel herbicide use associated with the GM crops, relative to their conventional counterparts.