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’s
Saskatoon Research Center, which has been monitoring GM crops since commercial
farming began six years ago. Canada’s experience provides valuable lessons for
other parts of the world, such as Europe, that don’t 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.
“If we move towards quite a lot of GM growing, there would have to be some
sort of zoning,” 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.
Advertisement
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. “Our studies have shown that pollen can travel at least
800 metres.” That’s eight times further than the official Canadian “safe”
separation of 100 metres for rape grown to supply pedigree seed. And it’s four
times further than the country’s 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 “plateau” 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’s “a good chance” he will recommend extending
separation distances.
What’s 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 “stacked” resistance is easily managed with other herbicides,
but only if farmers know the problem exists.
