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TECHNOLOGY & PLANTS: Glyphosate-resistant giant ragweed has spread in southern Ontario (Canada)



                                  PART 1


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TITLE:   GLYPHOSATE-RESISTANT GIANT RAGWEED HAS SPREAD IN SOUTHERN ONTARIO

SOURCE:  Digital Journal, USA

AUTHOR:  Stephanie Dearing

URL:     http://www.digitaljournal.com/article/300579

DATE:    23.11.2010

SUMMARY: "Monsanto recently announced that glyphosate-resistant giant ragweed had been identified in more soybean fields near Windsor. Until a small number of plants had been identified one field in 2008, Ontario has not had any glyphosate-resistant weeds. [...] Follow-up this summer has found the glyphosate-resistant ragweed in 16 fields out of 57 tested, Monsanto confirmed in a press release. All identified cases were located in Essex County."

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GLYPHOSATE-RESISTANT GIANT RAGWEED HAS SPREAD IN SOUTHERN ONTARIO

Winnipeg - Monsanto recently announced that glyphosate-resistant giant ragweed had been identified in more soybean fields near Windsor. Until a small number of plants had been identified one field in 2008, Ontario has not had any glyphosate-resistant weeds.

The first case of what was then a suspected case of glyphosate-resistant giant ragweed was found in 2008 by the University of Guelph, and confirmed in 2009. The resistant plants were found in a field in Essex County, near Windsor, Ontario.

Follow-up this summer has found the glyphosate-resistant ragweed in 16 fields out of 57 tested, Monsanto confirmed in a press release. All identified cases were located in Essex County. Speaking for Monsanto from the Winnipeg office, Dr. Mark Lawton reassured farmers who plant Monsanto's roundup ready soy beans, saying

 ?With the 2010 field research findings, we have a plan in place to follow-up with the growers in order to relay the findings and more importantly, suggest solutions for control. It is also important for the researchers to gather field history that may help explain the presence of this resistance in the impacted fields.?

The two University of Guelph researchers who originally found the glyphosate-resistant giant ragweed announced their find in 2009 in a press release said the find was significant because it was the first instance of glyphosate-resistant weeds in Canada.

It is believed the giant ragweed is the only weed species in Canada that is resistant to Roundup. In comparison, the United States has about 15 different weed species exhibiting resistance to glyphosate.

Roundup is Monsanto's trademark glyphosate-based herbicide. Monsanto has created a number of different crop seeds that are genetically modified to tolerate Roundup, including corn (maize), cotton, canola, and soy beans. The company is currently working on creating a Roundup-ready strain of wheat.

Speaking about this year's findings, Sikkema said

"We know that farmers view glyphosate as an important weed control tool so the appearance of glyphosate-resistant populations and solutions to address this challenge are an important area of research for us and the farmers who have been impacted. Where crop rotation occurs, familiar herbicides such as 2.4-D in winter wheat and dicamba based herbicides in corn are very effective at controlling these glyphosate-resistant populations of giant ragweed. Our current research is focused on solutions to manage these populations in soybean production.?

The University of Guelph researchers explained last year "Resistance evolves after a weed population has been subjected to intense selection pressure in the form of repeated use of a single herbicide. The herbicide controls all the susceptible weeds, leaving only those with a resistant gene to reproduce."

According to Sikkema, the identification of the glyphosate-resistant giant ragweed is

"... a very serious situation. In other jurisdictions, most glyphosate-resistant weed biotypes have been effectively managed with other herbicides and cultural practices. We?ll continue our research so we can make recommendations to growers on effective control options."

When it comes to dealing with the glyphosate-resistant giant ragweed, Monsanto's spokesperson said

"There are definitely some crop management practices that can increase the risk of resistant weeds developing. That is why we strongly recommend farmers scout their fields, follow sound crop rotation practices and use additional modes of action that complement the Roundup Ready® system to control problem weeds and reduce the likelihood of developing resistance.?

Monsanto recommends a number of steps to fight the resistant weed in Ontario. In the United States, Monsanto has started a program it calls the Roundup Ready Plus platform <http://monsanto.mediaroom.com/index.php?s=43&item=892>, which gives a small rebate to farmers for having to use other herbicides to combat glyphosate-resistant weeds. Monsanto also loosened restrictions on its patented technology <http://monsanto.mediaroom.com/index.php?s=43&item=890>, allow farmers to use herbicides made by two other companies in order to combat glyphosate resistance.

Until the giant ragweed developed resistance to glyphosate, the plant was known as "the worst nightmare" for those who suffer from hayfever.

It is thought that glyphosate-resistant giant ragweed is slower to spread than other resistant weeds found in the United States, such as Palmer Pigweed and horseweed, reported Delta Farm Press earlier this year <http://deltafarmpress.com/management/resistant-giant-ragweed>.

In Ontario, at least 43 plant species have been identified as being resistant to herbicides, reported OMAFRA in 2009 <http://www.omafra.gov.on.ca/english/crops/field/news/croppest/2009/01cpo09.pdf>.

Monsanto has a weed management strategy posted on its website for those wishing to learn more about managing glyphosate-resistant species <http://www.monsanto.com/weedmanagement/Pages/managing-weeds.aspx>.



                                  PART 2

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TITLE:   WEED SCIENTISTS AT U OF GUELPH CONTINUE RESEARCH ON GLYPHOSATE-RESISTANT GIANT RAGWEED IN CANADA

SOURCE:  Monsanto Canada, Canada

AUTHOR:  Press Release

URL:     http://www.monsanto.ca/about/news/2010/11_15_10.asp

DATE:    15.11.2010

SUMMARY: "Following up their work from last spring which confirmed the first finding of a glyphosate-resistant weed in Canada, University of Guelph weed scientists have now confirmed the presence of additional glyphosate-resistant populations in soybean fields in southwestern Ontario. Greenhouse testing of seed samples collected from southwestern Ontario in the fall of 2009 showed that an additional 16 fields had populations of giant ragweed (Ambrosia trifida) resistant to glyphosate."

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WEED SCIENTISTS AT U OF GUELPH CONTINUE RESEARCH ON GLYPHOSATE-RESISTANT GIANT RAGWEED IN CANADA

Additional giant ragweed populations confirmed in southwestern Ontario

(Winnipeg, MB ? November 15, 2010) ? Following up their work from last spring which confirmed the first finding of a glyphosate-resistant weed in Canada, University of Guelph weed scientists have now confirmed the presence of additional glyphosate-resistant populations in soybean fields in southwestern Ontario.

Greenhouse testing of seed samples collected from southwestern Ontario in the fall of 2009 showed that an additional 16 fields had populations of giant ragweed (Ambrosia trifida) resistant to glyphosate. As part of the ongoing research conducted by Dr. François Tardif and Dr. Peter Sikkema from the department of Plant Agriculture at the University of Guelph, giant ragweed seed was collected from 57 fields across Essex, Kent and Lambton Counties in 2009 in an attempt to document the distribution of glyphosate-resistant giant ragweed in Ontario. Samples collected from the 41 other fields were found to be effectively controlled with glyphosate and therefore, were not found to be resistant. All resistant populations from this survey were located in Essex County in southwestern Ontario.

?As was the case in our initial finding on a field near Windsor in 2008, we have been able to demonstrate that plants from the populations of giant ragweed we collected in 16 of the 57 fields survived when they were sprayed with glyphosate in the greenhouse,? said Dr. Tardif.

The populations in question underwent greenhouse testing by the university researchers, working in conjunction with Monsanto Canada, in order to confirm resistance. While over 30 other species of weeds in Canada have developed resistance to herbicides, glyphosate-resistant giant ragweed continues to be the only weed to be confirmed as glyphosate-resistant in Canada. In other countries around the world, 20 weed species ? including giant ragweed ? have been confirmed as resistant to glyphosate. Ten of those species are in the United States. All of these glyphosate-resistant weed biotypes have been managed with other herbicides and cultural practices.

Much of the ongoing research work is rightly focused on identifying herbicide solutions for management of glyphosate resistant giant ragweed and giving farmers effective solutions for management and control.

?We know that farmers view glyphosate as an important weed control tool so the appearance of glyphosate- resistant populations and solutions to address this challenge are an important area of research for us and the farmers who have been impacted,? said Dr. Sikkema, ?Where crop rotation occurs, familiar herbicides such as 2.4-D in winter wheat and dicamba based herbicides in corn are very effective at controlling these glyphosate-resistant populations of giant ragweed. Our current research is focused on solutions to manage these populations in soybean production.?

Based on the field research conducted this past year, Eragon? and FirstRate? herbicide were the most effective commercial products for control of the glyphosate-resistant giant ragweed. ?FirstRate worked well provided the population was not resistant to the Group 2 herbicides? said Dr. Sikkema, ?unfortunately other postemergence herbicide options in soybeans such as Blazer®, Reflex®, Basagran®, Liberty®, Classic®, Pursuit® and Pinnacle® and the soil applied herbicides Lorox®, Sencor®, Broadstrike? RC, Pursuit® and Command® did not provide commercially acceptable control. ?

There were a few new experimental treatments in soybeans that also worked very well in controlling the glyphosate-resistant giant ragweed. ?Use of dicamba with dicamba tolerant soybeans was one of those new treatments that was very effective in controlling glyphosate-resistant giant ragweed? said Dr. Sikkema. ?We are encouraging companies to pursue some of these new management strategies in soybeans to expand our control options for this issue.?

Dicamba tolerant soybeans are currently in Monsanto?s research and development pipeline but are not expected to be commercially available until 2014.

Monsanto takes product stewardship and claims of glyphosate resistance seriously and encourages growers to report suspected cases of resistance to Monsanto representatives so they can work with academics and extension services to investigate suspected cases, develop solutions for farmers and communicate the findings broadly.

Farmers are constantly reminded to include diversity in their cropping systems to reduce the likelihood of glyphosate resistance materializing in their fields. This includes a diverse crop rotation with multiple herbicide modes of action over time. Farmers are advised to use appropriate rates and other herbicides in their program where possible, including existing residual herbicides, to reduce the likelihood of glyphosate resistance developing in their fields.

?With the 2010 field research findings, we have a plan in place to follow-up with the growers in order to relay the findings and more importantly, suggest solutions for control,? explained Dr. Mark Lawton, Monsanto Canada?s technology development lead for eastern Canada. ?It is also important for the researchers to gather field history that may help explain the presence of this resistance in the impacted fields.?

Monsanto?s current best management practices include:

- Start with a clean field by either utilizing a burn down herbicide or tillage to control weeds early.

- Use Roundup Ready® technology as the foundation of a total weed management program.

- Add other herbicides or cultural practices where appropriate as part of the Roundup Ready cropping system.

- Use the right herbicide rate at the right time.

- Control weeds throughout the season and reduce the weed seed bank.

- Rotation to other Roundup Ready crops will add opportunities for introduction of other modes of action.

?There are definitely some crop management practices that can increase the risk of resistant weeds developing. That is why we strongly recommend farmers scout their fields, follow sound crop rotation practices and use additional modes of action that complement the Roundup Ready® system to control problem weeds and reduce the likelihood of developing resistance,? added Dr. Lawton.

Monsanto Canada is headquartered in Winnipeg, Manitoba. Monsanto Company is an agricultural company and a leading global provider of technology ? focused on enabling both small-holder and large-scale farmers to produce more from their land while conserving more of world?s natural resources such as water and energy. Learn more about our business and our commitments at www.monsanto.ca.



                                  PART 3

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TITLE:   U OF G RESEARCHERS FIND SUSPECTED GLYPHOSATE-RESISTANT WEED

SOURCE:  University of Guelph, Canada

AUTHOR:  Press Release

URL:     http://www.uoguelph.ca/news/2009/05/u_of_g_research_19.html

DATE:    07.05.2009

SUMMARY: "Researchers at the University of Guelph's Ontario Agricultural College have found a giant ragweed biotype that is showing resistance to the popular herbicide glyphosate. The plants are able to survive glyphosate use rates that kill normal susceptible weeds. [...] Currently, no weeds in Canada have been confirmed as resistant to glyphosate, the most often used herbicide globally. But in other countries around the world, 15 weed species ? including giant ragweed ? have been confirmed as resistant to glyphosate. Eight of those species are in the United States."

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U OF G RESEARCHERS FIND SUSPECTED GLYPHOSATE-RESISTANT WEED

Researchers at the University of Guelph's Ontario Agricultural College have found a giant ragweed biotype that is showing resistance to the popular herbicide glyphosate. The plants are able to survive glyphosate use rates that kill normal susceptible weeds.

"We've seen a difference in control of this giant ragweed biotype than what is normally expected when sprayed with glyphosate," said Prof. François Tardif of the Department of Plant Agriculture. The plants were still able to grow after an application of the herbicide at recommended levels, whereas susceptible ragweed did not survive.

"Glyphosate has become a tool of choice for the control for many weeds, so the appearance of a glyphosate resistant population can complicate management for growers," added Peter Sikkema, a plant agriculture professor at the University's Ridgetown Campus, who conducted the research with Tardif.

Currently, no weeds in Canada have been confirmed as resistant to glyphosate, the most often used herbicide globally. But in other countries around the world, 15 weed species ? including giant ragweed ? have been confirmed as resistant to glyphosate. Eight of those species are in the United States.

The giant ragweed population in question was brought to the researchers? attention in late 2008. It was found in a small portion of a 580-acre field of Roundup Ready® soybeans in Essex County. Weed seeds were collected from the area and used in greenhouse tests. In addition, researchers are collecting information on the field?s history, including crops grown, tillage practice and the herbicide program used.

The researchers stress that the results are preliminary and that, thus far, the suspected resistant biotype has been found in only the one identified area. Further greenhouse and field trials will be conducted on the weed biotype to confirm resistance as well as identify potential management options. Researchers will also be working to understand the genetic and biochemical basis for resistance.

Resistance evolves after a weed population has been subjected to intense selection pressure in the form of repeated use of a single herbicide. The herbicide controls all the susceptible weeds, leaving only those with a resistant gene to reproduce.

"This is a very serious situation," Sikkema said. "In other jurisdictions, most glyphosate-resistant weed biotypes have been effectively managed with other herbicides and cultural practices. We?ll continue our research so we can make recommendations to growers on effective control options."