Rape seed
Greenpeace believe GM crops pose irreversible long-term risks to the environment.
GM crops can transfer their modified genes to other, closely related plant species; and as pollen and seeds can be blown by the wind and/or be carried by insects, GM crops can pollinate with other crops over huge distances.
This is particularly worrying because GM oilseed rape and sugar beet have wild relatives in the UK. Any contamination of these wild species would be irreversible. Non-gm and organic maize or oilseed rape crops could also be contaminated.
If GM crops are commercialised, the risk of contamination will be massive. A recent study by the European Environment Agency confirmed:
- "At farm and regional scale, gene flow can occur over long distances and therefore complete genetic purity will be difficult to maintain."
- "Oilseed rape is cross compatible with a number of wild relatives and thus the likelihood of gene flow to these species is high."
- "It is predicted that plants carrying multiple [herbicide] resistance genes will become common post-GM release."
- "Volunteers (weeds in the following year's crops) may become more difficult to control with herbicide treatments."
A 2002 study of GM oilseed rape trials by the UK Department of Environment, Food and Rural Affairs came to very similar conclusions:
- "If GM oilseed rape is grown on a large scale in the UK, then gene flow will occur between fields, farms and across landscapes."
- Seed spillage and failure to clean combine harvesters is likely to be a significant source of GM contamination.
- GM oilseed rape volunteers survived for at least four years.
- Wild oilseed rape growing close to crop fields was contaminated.
Genetic contamination of non-GM and organic crops by GM varieties has already happened in Canada. According to a study by English Nature, so-called "superweeds" have started growing that are tolerant to three widely used herbicides when genes from separate GM varieties accumulate (called "gene stacking") in plants that grow from seed spilled at harvest ("volunteer plants"). The problem starts when one type of GM oilseed rape pollinates another, causing gene stacking and multiple herbicide tolerance. When seed is spilled at harvest, it remains in the ground and germinates later as unwanted weeds in crops of different species. These superweeds will be very difficult to eradicate - greater use of more powerful herbicides, especially in places like field margins where weeds tend to grow and can be important refuges for wildlife, could be very damaging.
The problem of contamination is especially significant in the UK because wild relatives of two of the crops being grown in the Farm Scale Evaluations live naturally in the UK. Wild relatives of oilseed rape and sugar beet include Wild Turnip (Brassica rapa) and Sea Beet (Beta vulgaris maritima).
