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A weed biotype that survives an herbicide treatment that previously was effective is considered to be herbicide resistant. Glyphosate resistant marestail, waterhemp, and kochia have become increasingly harder to manage as they become more common. Many of these uncontrolled weeds from last season produced seed and will be a continuing problem in future years within those fields.
The Roundup Ready® Xtend Crop System is an advanced weed management system, pending regulatory approvals, that is designed to help control herbicide resistant and tough-to-control broadleaf weeds in soybeans. Two of the components of the system are Roundup Ready 2 Xtend® soybeans and XtendiMax™ herbicide with VaporGrip™ Technology. Roundup Ready 2 Xtend soybeans are built on the Genuity® Roundup Ready 2 Yield® technology. They are the only soybean products that provide tolerance to both dicamba and glyphosate.
Figure 1. Relative volatility of various dicamba formulations
Dicamba and glyphosate herbicides are utilized to manage weeds on Roundup Ready 2 Xtend soybeans. XtendiMax herbicide with VaporGrip Technology is a new dicamba formulation which can provide a significant reduction in volatility compared to other commercially available dicamba formulations (Figure 1). XtendiMax herbicide with VaporGrip Technology is now approved by the EPA for in-crop use.
XtendiMax herbicide with VaporGrip Technology can be applied from before planting up to and including beginning bloom (R1 stage). The wide application window allows for the control of weeds when they are small (less than 4 inches) and more vulnerable, such as marestail at early burndown. The ability to use this product through the planting window will allow your Roundup Ready 2 Xtend soybeans to get a head start towards their high yield potential with minimal competition from weeds. With some other products, application restrictions limit use to 28 days or more before planting.
XtendiMax herbicide with VaporGrip Technology also offers potential soil activity for up to 14 days on certain small-seeded broadleaf weeds depending on rainfall and soil type.
A weed management program should always include traditional residual herbicides in pre-emergence and post-emergence applications that have different sites of action. Targeting weeds that have not yet emerged or are small (less than 4 inches) will make your weed management much more successful.
Use of XtendiMax herbicide with VaporGrip Technology has various application requirements including nozzle selection, set-back distances from sensitive areas, spray volume, etc. Always read and follow the most current pesticide label requirements.
Additional up-to-date information about the Roundup Ready Xtend Crop System and use of XtendiMax herbicide with VaporGrip Technology is available at the following websites:
A resource is available at http://takeactiononweeds.com which lists numerous herbicides by their site of action. The resource, which is supported by the United Soybean Board and industry, contains a Site of Action Lookup Tool and a downloadable Site of Action Chart. An additional source of herbicide recommendations focusing on reducing herbicide resistance issues is available from Roundup Ready PLUS® Crop Management Solutions, at: www.roundupreadyPLUS.com.
1 Peterson, D. and Shoup, D. 2016. The ongoing battle with pigweeds in soybeans. eUpdate Issue 593. Kansas State University Department of Agronomy. https://webapp.agron.ksu.edu/agr_social/eu_article.throck?article_id=1131 2 Herbicide Resistance. Department of Agronomy. Kansas State University. http://www.agronomy.k-state.edu/extension/weed-management/herbicide-resistance/. 3 Guideline to the management of herbicide resistance. Herbicide Resistance Action Committee. http://hracglobal.com/ 4 Sprague, C. 2016. Herbicide classification. Take action, herbicide-resistance management. United Soybean Board. http://takeactiononweeds.com/. Web sources verified 01/15/15. 170130153557