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[genet-news] PLANTS & TECHNOLOGY: Farmers relying on Roundup lose some of its benefit

                                  PART 1

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SOURCE: Purdue University, USA

AUTHOR: Press Release, by Brian Wallheimer


DATE:   14.04.2009

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WEST LAFAYETTE, Ind. - Roundup Ready crops have made weed control much easier for farmers, but a new study shows their reliance on the technology may be weakening the herbicide?s ability to control weeds.

Bill Johnson, a Purdue University associate professor of weed science, said farmers who plant Roundup Ready crops and spray Roundup or glyphosate-based herbicides almost exclusively are finding that weeds have developed resistance. It is only a matter of time, Johnson said, before there are so many resistant weeds that the use of glyphosate products would become much less effective in some places.

?We have weeds that have developed resistance, including giant ragweed, which is one of the weeds that drove the adoption of Roundup,? Johnson said. ?It?s a pretty major issue in the Eastern Corn Belt. That weed can cause up to 100 percent yield loss.?

Johnson was part of a team, including Steve Weller, a Purdue professor of horticulture and landscape architecture, that surveyed farmers in Indiana, Illinois, Iowa, Mississippi, Nebraska and North Carolina about their views on the ability of Roundup Ready crops to help control problematic weeds. A paper on the survey was published in the most recent edition of the journal Weed Technology. Researchers from Iowa State University, Mississippi State University, North Carolina State University, the University of Nebraska and Southern Illinois University Carbondale also contributed.

Roundup Ready crops are resistant to glyphosate, the active ingredient in Roundup. So, if a farm uses Roundup Ready crops, the herbicide can be sprayed on crops to kill weeds without damaging those crops.

Johnson said the problem has become farmers? overreliance on Roundup and Roundup Ready crops. Those who saw the most benefit from using Roundup, according to the survey, rotated between types of crops and those that were Roundup Ready and conventional crop varieties.

Johnson said this shows that subjecting weeds to different herbicides is important to keeping them from developing resistance to any particular herbicide.

?Farmers do not think resistance is a problem until they actually have it,? Johnson said. ?And they think the chemical companies can turn on the spigots and produce a new herbicide whenever they want. The problem is, since Roundup is so effective, there?s not been any money for new herbicide discovery.?

Johnson said farmers should treat Roundup and Roundup Ready crops as an investment and work to protect the technology. Rotating crops consistently and using various herbicides will slow the development of glyphosate-resistant weeds.

?Go after weeds with two different herbicides. That?s the best short-term solution,? Johnson said. ?We want to minimize the number of weeds resistant to Roundup. To do that, you want to minimize the exposure that a weed population has to Roundup. If you diversify a little bit, you?ll extend the life of the technology.?

Monsanto, the maker of Roundup, funded the survey. Johnson said the next step is studying the differences among management strategies in grower fields to see which will slow the build-up of glyphosate resistance.


ABSTRACT: U.S. Grower Views on Problematic Weeds 
and Changes in Weed Pressure 
in Glyphosate-Resistant Corn, Cotton, 
and Soybean Cropping Systems

Greg R. Kruger, William G. Johnson, Stephen C. Weller, Micheal D. K. Owen, David R. Shaw, John W. Wilcut, David L. Jordan, Robert G. Wilson, Mark L. Bernards, 
and Bryan G. Young

Corn and soybean growers in Illinois, Indiana, Iowa, Mississippi, Nebraska, and North Carolina, as well as cotton growers in Mississippi and North Carolina, were surveyed about their views on changes in problematic weeds and weed pressure in cropping systems based on a glyphosate-resistant (GR) crop. No growers using a GR cropping system for more than 5 yr reported heavy weed pressure. Over all cropping systems investigated (continuous GR soybean, continuous GR cotton, GR corn/GR soybean, GR soybean/non-GR crop, and GR corn/non-GR crop), 0 to 7% of survey respondents reported greater weed pressure after implementing rotations using GR crops, whereas 31 to 57% felt weed pressure was similar and 36 to 70% indicated that weed pressure was less. Pigweed, morningglory, johnsongrass, ragweed, foxtail, and velvetleaf were mentioned as their most problematic weeds, depending on the state and cropping system. Systems using GR crops improved weed management compared with the technologi
 es used before the adoption of GR crops. However, the long-term success of managing problematic weeds in GR cropping systems will require the development of multifaceted integrated weed management programs that include glyphosate as well as other weed management tactics.

                                  PART 2

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SOURCE: Stock & Land, Australia



DATE:   07.04.2009

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AUSTRALIAN farmers can expect better results from their Roundup Ready canola as better agronomic varieties are developed, according to Monsanto?s technical development leader Dave Moore, but he also warned that growers will have to use the technology responsibly if it is to continue as a useful tool.

?All we hear about is the tremendous benefits, which is fantastic, but growers have to remember it isn?t a silver bullet,? Mr Moore said.

?The surest way to wreck the system is to just use Roundup as the only herbicide all the time.

?Our American colleagues have showed us this well, and we need to learn from this mistake.?

Mr Moore said that Monsanto?s PRAMOG, Paddock Risk Assessment Management Option Guide, stewardship program for growers has been designed to keep the threat of glyphosate resistance at bay.

?The herbicide resistance issue is something I am passionate, we don?t want to go down the same track as America,? he said.

?We developed a program many years ago, PRAMOG, that is designed to show exactly how Roundup Ready canola will fit in a grower?s system.?

?PRAMOG looks at grower history, the probability of resistance issues, given existing modes of actions, it highlights in growers minds, the potential for glyphosate resistance.?

?It presents a field by field analysis of the risks of growing Roundup Ready canola and each farmer has to go through it each time they grow GM canola.?

?There?s been good feedback from farmers about how it works.?

?The key is to protect the sustainability of our product and the herbicide, and that?s why its so important that we train and accredit all users, and that growers and advisors are aware of their responsibility in that area.?

?If you use a single mode of action over and over again, you can end up with a great problem ? a farming system that relies on one or two modes of action isn?t a farming system.

He said Monsanto, owners of the Roundup Ready trait, would continue to work with seed companies such as Pioneer, Pacific and Nuseed to development new cultivars with better performance traits.

He said there had been promising trial work done on GM canola and that lines with yield advantages to the current ones were in the pipeline.

Mr Moore also flagged the possibility of looking at other GM traits, pointing to the example of improved water use efficiency in cotton, where work has led to the regulatory process beginning for the use of the gene on a commercial scale.

                                  PART 3

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SOURCE: Monsanto, USA



DATE:   21.04.1997

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A few environmental groups and anti-biotechnology activists have raised a number of questions about Roundup Ready soybeans, glyphosate (the active ingredient in Roundup® brand herbicides) and the regulatory systems that have approved and registered their use. To set the record straight and provide facts for interested people around the world, we examine the critic?s statements one by one, in many cases responding to their language, for proper context.


Critic?s Statement: Monsanto also claims that glyphosate is considered to be a herbicide with low risk for weed resistance. However, Monsanto itself notes that one important factor contributing to resistant weeds is frequent applications without crop or herbicide rotations. Yet no-till, single-herbicide monoculture is precisely what Roundup Ready soybeans are meant to encourage.

-	There has not been a verified case of weed resistance developing in the field as a result of Roundup being sprayed. Monsanto receives reports occasionally that speculate on resistance, and we always follow-up to understand any new developments. The mode of action unique to glyphosate, the active ingredient in Roundup, plus the herbicide?s lack of soil residual activity, have made it unlikely that resistant plants will appear over time in a weed population.

-	Although Monsanto does promote a no-till system to be used in conjunction with Roundup herbicide and Roundup Ready crops, this system is meant to conserve soil moisture and topsoil, an agronomic benefit that exists outside of Roundup Ready crops and their use.

-	In fact, Monsanto supplies much grower information to those farmers who purchase Roundup Ready soybeans and other modified crops. This information includes recommendations for crop rotation sequences (not monoculture), and it also provides guidelines for managing any Roundup Ready volunteers in following crops.

-	The need to manage crop rotations, soil tillage, and herbicide rotations is no different with Roundup Ready crops than with any other crops. Farmers are accustomed to minimum-tillage and soil-conservation practices which involve crop rotations. These rotations are no less necessary with Roundup Ready crops and Monsanto will recommend continuation of these practices with Roundup Ready and other modified crops.


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