BY JEREMY SIMES
GRAIN
SCIENCE
NEWS
Chem-resistant kochia
NEWSTUDYONGLYPHOSATE-RESISTANTWEED
THE TASK OF UNCOVERING NEW
methods to manage Western Canada’s first
glyphosate-resistant (GR) weed is under-
way in Lethbridge and at the University
of Alberta. The weed is called kochia, a
plentiful, large and competitive pest that
emerges early in the growing season, said
Bob Blackshaw, a weed scientist with Ag-
riculture and Agri-Food Canada (AAFC).
Kochia can be a factor that contrib-
utes to yield reduction, and Blackshaw
explained that tackling the weed economi-
cally benefits producers.
“Kochia is a common weed in southern
Alberta. If it’s not controlled, then farmers
will lose on their yields, if they have it.”
In order to combat the problem,
Blackshaw’s leading a project aimed to
determine the seed production potential,
the timing of seed development and the
environmental conditions when GR seeds
are inactive compared to kochia seeds that
are susceptible to glyphosate.
The project also seeks to identify
cost-e ective herbicides that can be used
to control GR kochia. That will be done
through pre-seed burndown applications,
chemfallow treatments and in-crop herbi-
cide applications.
The team is testing herbicides on wheat,
canola and field peas alongside kochia to
better understand how those crops react
to the sprays.
The GR-kochia problem came to light in
2011 when Blackshaw received a call from
a farmer who had trouble controlling the
weed on his field. After Blackshaw and a
team of researchers investigated three fal-
low fields in the Warner-Milk River area,
they confirmed a number of weeds were
glyphosate resistant.
Thereafter, Blackshaw, with fellow
researchers Linda Hall and Hugh Beck-
ie, surveyed 309 sites for GR kochia in
Alberta. Thirteen of those sites—seven in
Warner County, five in Vulcan and one
in Taber—had kochia with glyphosate
resistance.
It didn’t stop there, either: 10 other GR-
kochia sites were found in Warner prior to
the survey. Independent farmer testing in
2012 also found an additional nine sites,
including four in Forty Mile County, one
in Lethbridge and one in Cypress County.
Another survey by Beckie in 2013 found
GR kochia in 17 of 342 sites in southern
and central Saskatchewan and two of 283
sites in southern Manitoba.
Despite those small numbers, there’s
potential for the number of GR kochia
sites to increase, explained Beckie, an
AAFC research scientist who specializes
in herbicide-resistant weeds.
“Based on Group 2-resistant kochia, it
was everywhere in less than 20 years. So
because glyphosate is used more often
than Group 2 ever was in terms of num-
bers of acres and intensity of use, I would
expect that to be the same situation if not
quicker for GR kochia.”
The interprovincial spread of GR kochia
is largely due to seed dispersal from ma-
ture plants tumbling across the landscape.
Pollen transmission also causes the scat-
tering of the weed, said Beckie.
The team jumped on the GR-kochia
problem immediately, “thanks to the three
original growers who contacted us,” Beck-
ie explained. “We knew we had to quickly
survey the Prairies to see the extent of
the problem, and we will follow that up
with regular surveys to see how fast it’s
spreading.”
Glyphosate was introduced in 1974, and
has become the most widely used herbi-
cide in the world, according to a report by
Blackshaw.
“Initially, glyphosate was mixed with
other herbicides. However, when glypho-
sate went o patent in the 1990s and
became cheaper, then it was actually eas-
ier not to mix it with another herbicide,”
Blackshaw said.
That largely contributed to the develop-
ment of GR kochia. Through the survey,
the research team found farmers were
using only glyphosate to control their
weeds on fallow.
He recommended that farmers fight
back with integrated weed-management
practices such as tank mixing, crop rota-
tion and high seeding rates.
“That could increase producers’ costs,
but it pays o in the long run.”
Western Canadian Wheat Growers
vice-president Stephen Vandervalk ech-
oed the importance of best management
practices.
“It’s important to tackle GR kochia if
you have it,” said Vandervalk, who farms
near Fort Macleod. “We’re always looking
for a new herbicide. That’s not the fix,
though. It’s about breaking down resist-
ance, not just relying on new modes of
herbicide control.”
The team will do one last field test in
2015, and the project will conclude in
2016.
FIGHTING BACK:
Hugh Beckie (left) with
a glyphosate-resistant kochia plant.
Photo: Agriculture andAgri-FoodCanada
Spring
2015
Grains
West
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