STRAY pollen and seed from genetically modified oilseed rape, or canola, is
now so widespread in Canada that it is difficult to grow conventional or organic
strains without them being contaminated.
That is the stark message from Hugh Beckie of the agriculture ministry鈥檚
Saskatoon Research Center, which has been monitoring GM crops since commercial
farming began six years ago. Canada鈥檚 experience provides valuable lessons for
other parts of the world, such as Europe, that don鈥檛 yet allow commercial
production. It suggests that GM and non-GM varieties of some crops might have to
be kept far apart or even grown in separate, designated zones.
鈥淚f we move towards quite a lot of GM growing, there would have to be some
sort of zoning,鈥� says Jeremy Sweet of the National Institute of Agricultural
Botany in Cambridge. This is already done to prevent contamination of elite
conventional strains of sugar beet and potatoes, he says.
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Beckie, who spoke at the Weeds 2001 conference in Britain last week, stresses
that much depends on the particular crop. Plants such as wheat and soybeans are
relatively safe from contamination because they usually pollinate themselves.
But oilseed rape accepts pollen from neighbours.
Experiments show that pollen from GM oilseed rape travels much further than
expected, Beckie says. 鈥淥ur studies have shown that pollen can travel at least
800 metres.鈥� That鈥檚 eight times further than the official Canadian 鈥渟afe鈥�
separation of 100 metres for rape grown to supply pedigree seed. And it鈥檚 four
times further than the country鈥檚 175-metre separation for rape grown to supply
oil or food.
Only 0.07 per cent of plants at 800 metres were pollinated, but there was a
long 鈥減lateau鈥� between 50 and 400 metres where contamination was about 0.2 per
cent, dangerously close to the accepted 0.25 per cent contamination limit for
elite seed. Beckie says that there鈥檚 鈥渁 good chance鈥� he will recommend extending
separation distances.
What鈥檚 more, some GM plants are surviving in fields from year to year because
they have acquired resistance to more than one weedkiller by crossing with other
GM strains. Such 鈥渟tacked鈥� resistance is easily managed with other herbicides,
but only if farmers know the problem exists.