Skip to content
for a responsible, fair & sustainable food system

GM Oilseed Survives Longer in Soil – New blow to EU coexistence plans

Immediate release (30 Sep 2005)

Calls to Pete Riley 07903 341 065.

New research [1] has found that GM oilseed rape could contaminate non-GM crops 15 years after it was grown – longer than previously thought. This represent a major set back to plans to commercialise the crop and EU plans to introduce coexistence rules for growing GM and non-GM crops.

The research [2] looked at how long oilseed rape seeds can survive in the soil and then germinate after they were spilt at harvest. Previously it was thought that GM oilseed seed would persist in the soil for ten years [3]. However the new research on 5 sites across the England and Scotland predicts that one in twenty spilt seeds could survive in the soil for 9 years and 1% could still germinate fifteen years after the GM crop was harvested. The researchers found that some crops dropped 10,000 seeds per square metre (3575 per square metre average) compared with a normal sowing rate for oilseed rape of just 100 seeds per square metre.

The researchers concluded:

Even at 95% loss of the mean 3575 seeds per square metre shed at harvest, would still leave nearly 200 seeds per square metre. Such numbers would be highly likely to result in the presence of more than two volunteer plants per square metre in a rape crop sown 9 years after the HT crop. This density would exceed the European Union threshold of 0.9% adventitious presence of GM seeds in a non-GM crop, if the subsequent crop was ‘conventional’.

The European Commission Coexistence guidelines require measures to prevent contamination in non-GM crops exceeding 0.9% [4]. However, the EC advice to adopt the high threshold of 0.9% has been challenged by the opinion of a leading QC as “fundamentally flawed” and “wrong in law”. [5]

In fact, two plants per square metre would result in around 2% contamination. One plant per square metre, after 15 years, would still mean that the 0.9% threshold could be breached.

These results follow the publication of new results by DEFRA this week showing harmful effect on wildlife from GM herbicide tolerant crops found in the Farm Scale Evaluations persisted for at least two years [5].

Commenting for GM Freeze, Pete Riley said:

These research findings show that it will be impossible to grow GM oilseed rape without long term contamination problems – the concept of coexistence is looking like dream land . Farmers would not be able to predict what level of GM they could find in their non-GM crops. Their land would be blighted for 15 years or more by a GM crop grown by a previous owner. The Government should announce the end all GM oilseed rape experiments in the UK immediately so that farmers can get on with providing UK supermarkets and food and animal feed manufacturers with the GM-free products they are demanding.


Calls to Pete Riley 07903 341 065.


[1] Lutman PJW et al , 2005. Persistence of seeds from crops of conventional and herbicide tolerant oilseed rape (Brassica napus). Proc.R.Soc B (2005) 272, 1909-1915 22nd September 2005.

[2] The research was part of the BRIGHT project, published in 2004, which investigated the environmental and agronomic impacts of herbicide tolerant crops in typical arable rotations.

[3] Scientific Committee on Plants SCP/GMO-SEED-CONT/002-Final 13th March 2001 Opinion of the Scientific Committee on plants concerning the adventitious presence of GM seeds in conventional seeds.

[4] 2003/556/EC dated 23 July 2003, Commission Recommendation on guidelines for the development of national strategies and best practices to ensure the coexistence of genetically modified crops with conventional and organic farming.

[5] Legal opinion by Paul Lasok QC for The Five Year Freeze, Friends of the Earth, Which?, GeneWatch UK, The Soil Association and Greenpeace January 2005. For summary click here.

[6] The full report is at and for further information visit