HTIR-IPM for the West

A service of the Western Regional Work Group on Integrated Pest Management:
Consequences of Herbicide Tolerant and Insect Resistant Crops,
in cooperation with Colorado State University

News Headlines and Archives

Summaries of the latest IPM news items, with links to original sources and relevant responses or commentaries.

• October 2005
• June 2005
• January 2005
• December 2004
• July 2004
• June 2004

October 2005: Monsanto launches web site on managing weed resistance to herbicides

Monsanto now sponsors a web site, www.weedresistancemanagement.com, providing information on weed control strategies with the potential to minimize the risk of weed resistance occurring. Some features of the site include management recommendations for specific tough-to-control weeds, localized information for growers by region, recent news and updates, and information on how to determine whether a resistant weed is present in the field.

Monsanto, 2005. Monsanto underscores commitment to product stewardship, introduces web site for weed resistance management. Monsanto press release. http://www.monsanto.com/monsanto/layout/media/05/10-03-05.asp

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June 2005: Experts offer strategies for dealing with glyphosate-resistant weeds

The confirmation that glyphosate resistance has developed in several weed species in the South in recent years is prompting experts to propose strategies for delaying the development of resistance in other locations and in other species. Rotation to a non-Roundup Ready crop and the addition of other herbicides to the program are recommended. Greg Elmore of Monsanto and three weed scientists, Alan York and John Wilcut of North Carolina State University and Stanley Culpepper of the University of Georgia, offer their suggestions.

Cecil Yancy, 2005. Weed scientists develop plan to combat glyphosate resistance. Southeast Farm Press, 3 June 2005; published online at http://southeastfarmpress.com/news/060305-Glyphosate-resistance/.

Related story: Jim Langcuster, 2005. Glyphosate resistance a concern but not a calamity, expert says. Southeast Farm Press, 15 May 2005; published online at http://southeastfarmpress.com/news/051505-Glyphosate-resistance/.

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January 2005: Bt crops called a component of integrated pest management programs

Bt crops will be most effectively used as a component of IPM programs rather than as a stand-alone solution to pest problems, according to a Perspective paper published in the science journal Nature Biotechnology. Concern about the possible development of Bt resistance in insect populations remains a high priority. The authors, entomologists at Cornell University, review the theories of resistance development and the policies implemented or recommended to delay the development of resistance. The mixed strategy being used in Australia for Bt cotton is analyzed and other mixed methods are suggested. Traditional IPM methods will help delay the eventual development of resistance, ensuring the long-term effectiveness of transgenic varieties, and Bt crops have a role to play in IPM programs, according to the authors.

Sarah L. Bates, Jian-Zhou Zhao, Richard T. Roush, and Anthony M. Shelton, 2005. Insect resistance management in GM crops: past, present and future, Nature Biotechnology 23: 57-62; published online as 10.1038/nbt1056.

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December 2004: Glyphosate-resistant common ragweed confirmed in Missouri

The existence of a small population of glyphosate-resistant common ragweed has been confirmed by Monsanto, maker of glyphosate-based Roundup, and by Dr. Reid Smeda, a weed scientist at the University of Missouri. The patch of ragweed can survive up to 10 times the dose of Roundup that is effective on normal ragweed. Resistant populations have been found previously in two other species, marestail (also called horseweed) and ryegrass. Monsanto recommends a tank mix combining Roundup with another herbicide to combat cases of resistance.

Monsanto, 2004. Investigation identifies single case of glyphosate-resistant common ragweed in Missouri. Monsanto press release. Contacts: Janice Armstrong at Monsanto (www.monsanto.com) and Reid Smeda (smedar@missouri.edu) at the University of Missouri.

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July 2004: Study finds pollen drift may contaminate insect refuges in Bt corn fields

Pollen drift from Bt corn to an adjacent refuge resulted in Bt toxin expression in the refuge kernels, in a recent study done in the western region. If this phenomenon occurs in commercial fields, kernel-feeding insects would be exposed to the toxin in the refuge, which is supposed to be composed completely of non-Bt plants. What's more, the expression level in those kernels would be reduced compared to the Bt hybrid, a situation that is contrary to the high-dose strategy for avoiding resistance development. These findings could result eventually in changes in the placement or geometry of Bt refuges in corn, or in other measures that would reduce pollen drift to refuges.

Charles F. Chilcutt and Bruce E. Tabashnik, 2004. Contamination of refuges by Bacillus thuringiensis toxin genes from transgenic maize, PNAS 101: 7526-7529; published online before print as 10.1073/pnas.0400546101.

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June 2004: Weed scientists call for forum on stewardship of glyphosate-resistant technology

Weed scientists and agricultural commodity groups should discuss how to preserve the value of glyphosate-resistant technology in the face of market pressure to use and perhaps over-use glyphosate resistance as a management tool, according to a group of weed scientists. Mike Owen from Iowa State University, Chris Boerboom from the University of Wisconsin, Stanley Culpepper from the University of Georgia, Mark Loux from The Ohio State University, Tom Mueller from the University of Tennessee, David Shaw from Mississippi State University, Christy Sprague from Michigan State University, and John Wilcut from North Carolina State University are suggesting that interested parties meet in November to discuss the possibilities. Read their letter formatted as a PDF document.

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