Using XtendiMax® herbicide with VaporGrip® Technology, a Restricted Use Pesticide, as a Burndown for Pigweeds and Marestail and for In-season Weed Control in the Roundup Ready® Xtend Crop System

The Roundup Ready® Xtend Crop System includes the herbicide-resistant crops Roundup Ready 2 Xtend® soybeans, XtendFlex® soybeans, and in-crop applications of XtendiMax® herbicide with VaporGrip® Technology, a Restricted Use Pesticide (RUP), which must be used with VaporGrip® Xtra Agent or an equivalent Volatility Reduction Adjuvant (VRA). The combination can provide up to 14 days of soil activity on certain small-seeded broadleaf weeds including Palmer amaranth, waterhemp, and marestail.* Residual control should be accomplished with the use of different site of action herbicide products tank-mixed with XtendiMax® herbicide with VaporGrip® Technology (for approved tank-mix products and nozzles, please visit XtendiMaxApplicationRequirements.com). Plant-back restrictions apply to crops that are not tolerant to dicamba by genetics or by herbicide-resistant traits.  

Actively growing weeds can quickly “eat into” crop yield and profitability by using the nutrients, water, and light that crops need to help maximize yield potential. Starting the growing season clean and applying herbicides when weeds are actively growing and less than 4-inches tall greatly improves herbicide efficacy. In minimum tillage situations, apply XtendiMax® herbicide with VaporGrip® Technology with VaporGrip® Xtra Agent or an equivalent volatility reducing adjuvant (VRA), plus a Roundup® brand glyphosate-only agricultural herbicide and an approved drift reducing adjuvant (DRA) with a soil residual herbicide prior to planting. In conventional tillage situations, especially under dry conditions, apply XtendiMax® herbicide with VaporGrip® Technology with VaporGrip® Xtra Agent or an equivalent VRA, tank-mixed with a soil residual herbicide at planting to provide weed control on early weed flushes like Palmer amaranth prior to activation of the soil residual herbicide by rain or irrigation. 

Tough-to-control weeds such as waterhemp, Palmer amaranth, and marestail can be managed with the use of XtendiMax® herbicide with VaporGrip® Technology. 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 utilize 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.

Roundup Ready 2 Xtend® Soybeans

Roundup Ready 2 Xtend® Soybeans offer tolerance to dicamba and glyphosate. Dicamba tolerance offers improved control over herbicide-resistant and other tough-to-control broadleaf weeds. 

Pigweed Species Control

Bayer research in the Midwest and South in 2019 points to the effectiveness and use of XtendiMax® herbicide with VaporGrip® Technology as a burndown herbicide. The research focused on tank mixes. The first was a mix of XtendiMax herbicide with VaporGrip Technology (22 fl oz/acre) plus Roundup PowerMAX® herbicide (32 fl oz/acre) plus a DRA. The second was a mix of Enlist One® Herbicide with Colex-D® Technology (25 fl oz/acre) plus Roundup PowerMAX herbicide (32 fl oz/acre). The third tank-mix was Enlist One Herbicide with Colex-D Technology (25 fl oz/acre) plus Liberty® 280 SL Herbicide (32 fl oz/acre). The three tank mixes were similar for percent weed control 14 days after application (Figure 1). After 21 days, the percent weed control for the XtendiMax® herbicide with VaporGrip® Technology tank mix was significantly higher than the other two tank mixes showing better burndown control and the soil activity benefit of XtendiMax® herbicide with VaporGrip® Technology for controlling the new flush of pigweed species that emerged after the POST were applied (Figures 1 and 2).

Marestail Control

The control of marestail at three locations 28 days after treatment was significantly higher with tank mixes of XtendiMax® herbicide with VaporGrip® Technology (22 oz/acre) plus Roundup PowerMAX® Herbicide (32 fl oz/acre) than tank mixes of Enlist One® Herbicide with Colex-D® Technology at rates of 25 and 32 fl oz/acre plus Roundup PowerMAX® Herbicide (32 fl oz/acre) (Figure 3). This is because XtendiMax® herbicide with VaporGrip® Technology, in addition to providing post-emergence and burndown control, is also helping to prevent another flush of weeds to emerge due to its soil activity benefit keeping fields clean longer compared to the competitive treatment. The tank mixes with XtendiMax® herbicide with VaporGrip® Technology included a DRA at 0.5% v/v.

XtendFlex® Soybeans

XtendFlex soybeans have tolerance to dicamba, glyphosate, and glufosinate which provides farmers greater flexibility for managing tough-to-control weeds including waterhemp, Palmer amaranth, marestail, PPO-inhibitor resistant weeds, and glyphosate resistant weeds. The Roundup Ready® Xtend Crop System with XtendFlex® Soybeans controls 335+ weeds.** 

Research trials conducted in Illinois, Indiana, Minnesota, Missouri, and Tennessee demonstrated the benefit of planting XtendFlex soybeans. 

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 reducing 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)
  • XtendiMax herbicide with VaporGrip Technology (22 fl oz/acre) + Roundup PowerMAX® Herbicide (32 fl oz/acre) + DRA (0.5% v/v) or 
  • XtendiMax herbicide with VaporGrip Technology (22 fl oz/acre) + Roundup PowerMAX® Herbicide (32 fl oz/acre) + DRA (0.5% v/v) + Warrant Herbicide (48 fl oz/acre) 
• Mid POST:
  • Cobra® herbicide (10 fl oz/acre) 
  • Warrant® Ultra herbicide (50 fl oz/acre)
  • Liberty® herbicide (32 fl oz/acre) + AMS 

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 4).

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 5).

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Applicators of XtendiMax® herbicide with VaporGrip® Technology MUST review the label, follow state regulations for application, and use VaporGrip® Xtra Agent or an equivalent Volatility Reduction Adjuvant. Additional information can be found at www.XtendiMaxApplicationRequirements.com. 

*Results may vary, depending on rainfall and soil type. Always use dicamba with traditional residual herbicides in pre-emergence and postemergence applications that have different, effective sites of action, along with other Diversified Weed Management Practices.

**Based on approved EPA herbicide labels for the herbicides recommended for use in each system as of January 2021.