By Peter Hemphill


The "escape" of genetically modified canola on to roadsides is not likely to
develop into uncontrollable wild populations contaminating conventional
crops.


Four years of research by the University of Melbourne has shown volunteer
canola competes poorly with other plants and does not establish breeding
populations on roadsides.

And other research has shown that concerns of roadside canola crossbreeding
with other canola plants are unfounded.

University of Melbourne agronomy lecturer Rob Norton said that, while the
study looked at the behaviour of conventional canola growing on roadsides,
the findings would apply equally to genetically modified plants.

The research results come after windrowed Roundup Ready canola blew on to a
road in the Horsham district last week, prompting angry responses from
anti-GM campaigners.

University researchers surveyed more than 200km of Wimmera and southern
Mallee roadsides in 2002, 2003, 2004 and 2006, and found low densities of
canola every year.

But in most cases, there was no correlation between population location and
density from one year to the next.

Dr Norton said canola was not a roadside weed which persisted.

"The plants you see come from seeds dropped during transport, establish,
grow, possibly set seed, but don't persist with new generations," he said.

"The Office of the Gene Technology Regulator in its risk assessment of GM
canola recognised that canola is a poor competitor with established plants."

Dr Norton said the methods to control roadside growth of conventional canola
were exactly the same as GM canola: slashing, grading and spraying with
different herbicides mixes.

He said good roadside management of volunteer canola plants meant councils
should not be using a single type of herbicide to control them but a mix of
alternatives.

"Every year, we do the survey and the results essentially come up the same."

Dr Norton said they recorded the numbers of canola plants along every
kilometre of road and found that, where the populations peaked in one year,
this generally did not follow in subsequent years.

"If a population was building up in density, it would keep on building up in
that one place," he said.

"There is no evidence of an ongoing population of roadside weeds in the same
place."

Dr Norton said roadside canola was effectively a "one-year population".

"We looked more closely at spots with a high density of canola plants and
found that virtually everything was within 2m of the bitumen, that is, in
the area that had been graded.

"The canola was only able to establish where the soil had been disturbed.

"Of interest, the density of canola along roadsides is no more common where
canola was the crop in the adjacent paddock."

The Co-operative Research Centre for Weeds published research in 2004 to
determine if volunteer canola populations were the results of grain spills
or from a build-up of a "seed bank" at the site.

The research, by Jeanine Baker and Chris Preston of the University of
Adelaide, compared the DNA of the seeds with that of the parent plant, and
found they were identical.

"This suggests that cross-pollination is rare in roadside canola
populations, even when more than one cultivar (variety) is present in the
population," Dr Norton said.

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