SASKATOON – Genetically engineered canola can spread its herbicide resistance to closely related weeds, which shows the potential to create hard-to-kill plant pests, say a group of Danish scientists.
In the current issue of Nature, a respected science journal, a report from the Riso National Laboratory in Roskilde, Denmark said researchers had been able to make an Argentine-type canola breed with a weedy form of Polish canola common in Europe. The hybrids were fertile. Some plants produced up to 450 seeds which were capable of growing in the next season.
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And the scientists found the hybrids themselves can breed with weeds, passing herbicide resistance into the general weed population.
Thomas Mikkelsen, one of the Danish scientists involved in the project, said their results prove there is potential for herbicide resistance to be passed to weeds. The herbicide-resistant weeds were created in the laboratory, but Mikkelsen said it could happen in the field.
“There is a possibility, but we don’t really know how often that might happen under normal circumstances.”
Mikkelsen said the study results should not lead to the conclusion that transgenic oilseeds should not be produced, but “perhaps we should think about what traits we put into (canola), because there seems a chance the traits can be spread.”
For Canadian farmers, the Danish discovery means they can’t forget about weeds if they are growing herbicide-resistant crops, said Tony Zatylny, crop production co-ordinator with the Canola Council of Canada in Winnipeg.
“Just because we’re using new technologies like herbicide-resistant canola varieties does not exclude the farmer from having to follow good agronomic practices, which includes rotation of herbicides,” he said.
“If farmers follow these practices, there shouldn’t be a problem.”
Since the herbicide resistance is protection from only one chemical, weed control with a different chemical would likely kill the hybrid weed.
Other factors also limit the possibility of herbicide-resistant weed populations.
“These things are not Frankenstein monsters,” said Wilf Keller, a scientist with the National Research Council who has helped develop a herbicide-resistant canola.
Because canola is a rotational crop, he said there will be big gaps between chances to cross-fertilize. Most Polish-type canolas finish flowering before Argentine plants start flowering, he said.
Both Zatylny and Keller said canola growers should not be alarmed because it is theoretically possible to spread herbicide resistance from one plant to another.
“Indicating that you can make 400 seeds in a greenhouse or a lab is quite a bit different from the reality of the field,” said Keller.
And even if a possibility of creating herbicide-resistant weeds does exist, “you have to weigh the risk against the benefit of this kind of technology.”
Since weeds probably cost prairie canola producers $100 million per year, transgenic canolas are a valuable tool, he said.
