Farmers have been dealing with the issue of herbicide-resistant weeds since the 1950s, and it is a simple fact that growers use multiple methods to control weeds, including herbicides, tillage and mechanical weed removal. Resistance is a herbicide issue. It is not directly related to biotech-enhanced crops and includes herbicides beyond glyphosate, the active ingredient in Roundup agricultural herbicides.

History demonstrates that growers manage cultivation of their crops through the occurrence of weed resistance, and that the affected herbicide products continue to be valuable and important. Roundup Ready® sugar beets offer a new, effective weed control tool to manage weeds that are not being controlled by current herbicide programs for sugar beets. For example, kochia is resistant to ALS-inhibiting herbicides.

Worldwide, there are 13 weed species with biotypes confirmed to be resistant to glyphosate, according to the International Survey of Herbicide Resistant Weeds available at www.weedscience.com. Eight of these resistant biotypes are found in the United States. Some are found in areas where Roundup Ready crops are not grown. Roundup agricultural herbicides continue to be the cornerstone for weed management programs in Roundup Ready crops.

Glyphosate-resistant weeds found in the United States in areas where Roundup Ready crops are grown:

• Palmer amaranth (Palmer pigweed)
  Confirmed in Georgia in 2005.
  Suspected in Tennessee, North Carolina and Arkansas
• Common ragweed
  Arkansas, Missouri
• Marestail (Horseweed)
  Arkansas, California, Delaware, Kentucky, Indiana, Maryland, Missouri, Mississippi, Nebraska, North Carolina, New Jersey, Ohio, Pennsylvania and Tennessee
• Waterhemp
  Missouri
• Giant ragweed
  Indiana, Ohio

Note: California and Nebraska are the only three states where sugar beets are grown and where glyphosate-resistant weeds have been found.

The other three weeds in the United States are:

• Italian Ryegrass
  Oregon (orchard setting)
• Rigid Ryegrass
  California (discovered in almonds)
• Hairy Fleabane
  California (roadsides)

For more information, visit http://www.weedscience.org.

Monsanto, the maker of Roundup agricultural herbicides, takes product stewardship and claims of resistance to glyphosate very seriously. Monsanto continually evaluates its recommendations for weed control and provides alternate weed control recommendations for any biotype confirmed as resistant. When glyphosate-resistant weed biotypes have been identified, they have been effectively managed with other herbicides and/or cultural practices.

Monsanto is committed to working with growers to address weed resistance to glyphosate. Monsanto encourages growers to report incidents of repeated non-performance of a Monsanto-branded herbicide to their local Monsanto retailer or to call 1-800-ROUNDUP. Monsanto investigates and addresses potential resistance, and implements control recommendations where resistance is observed.

Weed Resistance Management Resources
http://www.weedresistancemanagement.com
Monsanto’s educational weed resistance management Web site provides its customers comprehensive and timely information on weed control strategies for Roundup Ready cropping systems. Weed Resistance Management Kits are available online. These kits contain reference materials and other items designed to help crop producers and crop advisors steward herbicides and manage weed resistance. The kits include fact sheets detailing practical management tactics for hard-to-control weeds.

2007 Monsanto Technology Use Guide (TUG)
All growers of Roundup Ready crops receive a Monsanto TUG, which includes weed resistance management information, as well as specific application guidelines by crop. The TUG can be found on-line at http://www.weedresistancemanagement.com.

International Survey of Herbicide-resistant Weeds - http://www.weedscience.org
A comprehensive listing of herbicide-resistant weeds worldwide, the survey is a searchable database of resistant weeds by species, location and herbicide mode of action.

Online Weed Resistance Management Learning Centers (WRMLC)
These computer-based training modules educate growers and agriculture industry professionals on how to reduce the potential development of resistant weeds

Sugar Industry Biotech Council - http://www.sugarindustrybiotechcouncil.org/learning-module/index.htm

Other sites offering WRMLC modules include:
National Corn Growers Association – http://www.ncga.com
American Soybean Association – http://www.soygrowers.com/members/WRM/
National Cotton Council - http://www.cotton.org/tech/pest/wrm/
National Association of Wheat Growers - http://www.wheatworld.org/
American Sugar Beet Growers Association - http://www.americansugarbeet.org/
U.S. Canola Association - http://www.uscanola.com/
Beet Sugar Development Foundation - http://www.bsdf-assbt.org/index.htm

2007 Weed Resistance Management General Recommendations
Monsanto recommends the following general guidelines for minimizing the risk of weed resistance:

• Scout fields before and after herbicide applications.
• Start with a clean field by utilizing either a burndown herbicide or tillage.
• Control weeds early when they are small.
• Use the right herbicide product at the right rate and at the right time. For information on applications rates and timing, consult the herbicide product label.
• Add other herbicides (e.g., a selective and/or a residual herbicide) and cultural practices (e.g., tillage or crop rotation) where appropriate.
• One method for adding other herbicides into a continuous Roundup Ready system is to rotate to other Roundup Ready crops.
• Control weed escapes and prevent weeds from setting seeds.
• Clean equipment before moving from field to field to minimize the spread of weed seed.
• Use seed certified as free from weed seed as possible.
• Report any incident of repeated non-performance on a particular weed to the local Monsanto representative, retailer or county extension agent.