Guelph, Ontario, Canada
September 5, 2007
A new six-year cropping study
completed by the University of
Guelph and Agriculture and
Agri-Food Canada (AAFC) on the agronomic fit of Roundup
Ready® corn and Roundup Ready® soybeans in Eastern Canadian
cropping systems has confirmed that incorporating the Roundup
Ready system into cropping rotations is a viable and effective
production system for Eastern Canadian growers.
The study - titled, "Long-term effects of Roundup Ready
Compared to Conventional Herbicide Systems in Ontario" -
also found that the use of Roundup Ready crops over the six-year
period was sustainable in both conventional and no tillage
production systems. When winter wheat was added to a Roundup
Ready soybean/corn rotation, growers also tended to get yield
benefits in corn and soybean production in subsequent years.
The study also confirmed what many growers already know about
the Roundup Ready system - the use of glyphosate consistently
provided better mid-season weed control in corn and soybean when
compared to conventional herbicides.
There are also many more findings that should benefit Eastern
Canadian growers and help them plan their crop rotations for
maximum weed control and improved yields.
"Growers may be interested in the study's finding that shows the
inclusion of winter wheat in the rotation resulted in a
different weed community than in corn and soybeans," said Dr.
Clarence Swanton of the University of Guelph's Department of
Plant Agriculture and one of several authors of the study. "As
well, over the six years of this experiment at the locations
tested, we found little evidence for an increase in weeds that
have a natural tolerance to glyphosate in the Roundup Ready
system nor did volunteer crops of Roundup Ready soybean or corn
create a problem for us."
The objective of the study - which was funded by
Monsanto Canada - was to
compare the effects of continuous use of glyphosate or
conventional herbicides on weed control, weed biodiversity, crop
yield and yield stability of glyphosate-resistant corn and
soybean grown in rotation with, or without, winter wheat.
Some growers in Ontario have been cautious about growing more
than one Roundup Ready crop, thinking it isn't viable or that it
might not be a good agronomic choice. Now with some thorough,
multi-year research on the long-term effect of Roundup Ready
systems compared to conventional herbicide systems, they have
the data they need to make an informed choice.
"This new study provides valuable, science-based research that
gives growers the confidence to grow both Roundup Ready soybeans
and Roundup Ready corn if that is the best option for their
farm," said Dr. Mark Lawton, Monsanto's technology manager,
Eastern Canada. "It's a sound agronomic decision, as well as the
best economic one in terms of weed control and yield."
Lawton added that Monsanto gets a lot of questions from
customers in Eastern Canada about proper agronomic management of
Roundup Ready crops, particularly about what impact growing
multiple Roundup Ready crops might have on managing glyphosate
resistance on their farm.
"Good stewardship practices such as field scouting, starting
with clean fields and adding other herbicides and cultural
practices will help growers manage the likelihood of developing
glyphosate resistance when they choose to grow both Roundup
Ready soybeans and Roundup Ready corn on their farm," said
Lawton. "We're very pleased to fund this sort of valuable
research for the benefit of growers and appreciative of the
opportunity to collaborate with both government and university
researchers on this study."
About the Study
- Conducted by researchers
at the University of Guelph and Agriculture and Agri-Food
Canada - Dr. C. J. Swanton, University of Guelph; Dr. P. H.
Sikkema, University of Guelph; Dr. A. S. Hamill, AAFC; Dr.
F. J. Tardif, University of Guelph; Dr. R. H. Gulden,
University of Guelph.
- Six years of field trial
work took place at five locations in Ontario (two no-tillage
and three conventional tillage) between 2000 and 2005.
- Treatments included a two
crop rotation system: Roundup Ready corn/Roundup Ready
soybeans compared to conventional corn/conventional
soybeans; and a three crop rotation system: Roundup Ready
corn/Roundup Ready soybeans/winter wheat compared to
conventional corn/conventional soybean/winter wheat. All
rotations were grown at all locations each year.
Summary of key findings
- Over the six years of
the study, the continuous use of Roundup Ready crops was
a viable production system for conventional and no-till
cropping systems.
- The use of Roundup
agricultural herbicide provided better mid-season weed
control in both Roundup Ready corn and soybeans compared
to conventional herbicide weed control programs.
- Volunteer Roundup
Ready soybeans or corn were not a weed management issue.
- Yields of Roundup
Ready crops were equal to or better than conventional
crops.
- The inclusion of
winter wheat in the rotation had a tendency to improve
corn and soybean yields.
- Over the six years of
the study, there was little evidence for the selection
of weeds that were naturally tolerant to glyphosate in
the Roundup Ready system.
- In no-tillage corn and
soybeans, more weed species were observed in the
conventional herbicide system than with the Roundup
Ready system by mid-season.
- In conventional
tillage soybeans, the number of weed species observed
was the same in both herbicide systems. In conventional
tillage corn, the number of weed species observed was
greater in the Roundup Ready system.
- The inclusion of
winter wheat resulted in a different weed community than
in corn or soybeans.
A complete copy of "Long-term
effects of Roundup Ready Compared to Conventional Herbicide
Systems in Ontario," is available from the
University of Guelph,
Department of Plant Agriculture or Monsanto Canada's Eastern
Business office in Guelph, Ontario. |
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