The Roundup Ready® Xtend Crop System has expanded to include XtendFlex® soybeans and in-crop applications of the dicamba herbicide product XtendiMax® herbicide with VaporGrip® Technology, a restricted use pesticide, which must be used with VaporGrip® Xtra Agent (or an equivalent Volatility Reduction Adjuvant (VRA). XtendFlex soybeans are tolerant to dicamba, glyphosate, and glufosinate. The herbicide resistance combination of XtendFlex soybeans gives farmers greater flexibility for managing tough-to-control weeds such as waterhemp, Palmer amaranth, and marestail, including those with PPO-inhibitor and glyphosate resistance. When needed, a glufosinate herbicide can be used during the growing season to help manage weeds resistant to glyphosate.
Residual control should be accomplished with the application of herbicides with effective sites of action tank-mixed with XtendiMax herbicide with VaporGrip Technology (for approved tank-mix products and nozzles, please visit www.XtendiMaxApplicationRequirements.com). Plant-back restrictions apply to crops that are not tolerant to dicamba by genetics or by herbicide-resistant traits. Repeated use of herbicides with the same site of action may lead to selection for resistant weeds; therefore, it is important to use the labeled herbicide rates to help maximize weed control and include other herbicides with different sites of action. Integrated weed management principles that should be followed include:
The scouting of fields before and after herbicide applications.
The use of broad-spectrum soil-applied residual herbicide(s).
The use of sequential herbicide applications with multiple, effective sites of action.
The use of appropriate herbicides and product rates for respective weed species at sizes present.
The use of crop rotation, where possible, can help manage weeds because different herbicides with different sites of action can be used.
The use of non-chemical weed control practices such as tillage, cultivation, cover crops, and row spacing.
Research trials conducted in Illinois, Indiana, Minnesota, Missouri, and Tennessee demonstrated the benefit of planting XtendFlex soybeans and the use of XtendiMax herbicide with VaporGrip Technology. The trials were comprised of PRE (at planting), Early POST (14 to 21 days after PRE), and Mid-POST (14 days after early POST) applications. Weed control ratings were recorded 14 days after the Early POST application and 28 days after the Mid-POST application.
The herbicides used in the trials consisted of:
- PRE/At planting:
- flumioxazin (2 oz wt/acre)
- Warrant® Herbicide (48 fl oz/acre) + metribuzin (0.33 lb wt/acre)
- XtendiMax® herbicide with VaporGrip® Technology, a restricted use pesticide (RUP) (22 fl oz/acre) + Warrant Herbicide (48 fl oz/acre) + drift reduction adjuvant (DRA) (0.5% v/v)
- XtendiMax herbicide with VaporGrip Technology (22 fl oz/acre) + flumioxazin (2 oz wt/acre) + DRA (0.5% v/v)
- Early POST:
- Reflex® herbicide (16 fl oz/acre)
- Warrant Herbicide (48 fl oz/acre)
- XtendiMax herbicide with VaporGrip Technology (22 fl oz/acre) + Roundup PowerMAX® herbicide (32 fl oz/acre) + DRA (0.5% v/v)
- Mid POST:
- Cobra® herbicide (10 fl oz/acre)
- Warrant® Ultra herbicide (50 fl oz/acre)
- Liberty® herbicide (32 fl oz/acre) + Ammonium sulfate (AMS) (2.5% v/v)
The average percent of waterhemp control was significantly greater in XtendFlex® soybeans when tank mixes included XtendiMax herbicide with VaporGrip Technology compared to when only PPO-inhibiting herbicides were used in PRE, Early Post, and Mid-POST applications (Figure 1).
The average percent of Palmer amaranth control 14 days after Early POST and 28 days after Mid-POST was significantly greater in XtendFlex soybeans when tank mixes included XtendiMax herbicide with VaporGrip Technology compared to when only PPO-inhibiting herbicides were used in PRE, Early POST, and Mid-POST applications (Figure 2).
Applicators of XtendiMax® herbicide with VaporGrip® Technology MUST review the label and follow state regulations for application. Additional information can be found at www.XtendiMaxApplicationRequirements.com.