How to Control Palmer Amaranth and Waterhemp in Soybeans

Having explored resistance issues with waterhemp and Palmer amaranth, let's turn our attention to discuss some control options for soybean in fields where resistance has been observed.

Weed control options in soybeans

Palmer amaranth and waterhemp have an amazing ability to develop resistance to herbicides. Those have exhibited resistance to eight herbicide groups: Groups 2, 3, 4, 5, 9, 14, 15 and 27.

But that doesn’t mean farmers are out of options to combat these pests. By taking advantage of multiple modes of action, along with crop and chemistry rotation, these difficult to control species can be effectively managed. There are very few cases of resistance to all the listed herbicide groups mentioned.  

Here are some suggested herbicide options for common soybean cropping systems: 

Conventional Soybean

  • Spring Burndown
    2,4-D, glyphosate or glufosinate + paraquat
  • Pre-Plant*1,4
    Authority® Elite, Fierce®, Envive®, Sharpen®, Sonic®, Surveil®
    Valor® SX, Valor® XLT, or Verdict® + Group 15 herbicide5
  • Pre-Emerge**2,4
    Boundary®, Authority® MTZ, Canopy®, or metribuzin + Group 15 herbicide5
  • Post-Emerge***
    Cobra®, fomesafen, or Ultra Blazer® + Group 15 herbicide5
  • Salvage3
    Dicamba

Glyphosate-tolerant Soybean

  • Spring Burndown
    2,4-D, glyphosate or glufosinate + paraquat
  • Pre-Plant*1,4
    Authority® Elite, Fierce®, Envive®, Sharpen®, Sonic®, Surveil®
    Valor® SX, Valor® XLT, or Verdict® + Group 15 herbicide5
  • Pre-Emerge**2,4
    Boundary®, Authority® MTZ, Canopy®, or metribuzin + Group 15 herbicide5
  • Post-Emerge***
    Glyphosate + fomesafen + Group 15 herbicide5
  • Salvage3
    Glyphosate + Cobra® or Ultra Blazer®

LibertyLink®-tolerant Soybean

  • Spring Burndown
    2,4-D, glyphosate or glufosinate + paraquat
  • Pre-Plant*1,4
    Authority® Elite, Fierce®, Envive®, Sharpen®, Sonic®, Surveil®
    Valor® SX, Valor® XLT, or Verdict® + Group 15 herbicide5
  • Pre-Emerge**2,4
    Boundary®, Authority® MTZ, Canopy®, or metribuzin + Group 15 herbicide5
  • Post-Emerge***
    Liberty® 280 + fomesafen + Group 15 herbicide2
  • Salvage3
    Liberty® 280

Enlist E3™ Soybean5

  • Spring Burndown
    Enlist Duo™ + paraquat
  • Pre-Plant*1,4
    Enlist Duo™ + Authority® Elite, Fierce®, Envive®, Sharpen®, Sonic®, Surveil®, Valor® SX, Valor® XLT, or Verdict® + Group 15 herbicide2
  • Pre-Emerge**2,4
    Boundary®, Authority® MTZ, Canopy®, or metribuzin + Group 15 herbicide5
  • Post-Emerge***
    Enlist Duo™ + Group 15 herbicide2
  • Salvage3
    Enlist Duo™

Roundup Ready 2 Xtend® Soybean6

  • Spring Burndown
    XtendiMax® + glyphosate or glufosinate + Paraquat
  • Pre-Plant*1,4
    XtendiMax® + Authority® Elite, Fierce®, Envive®, Sharpen®, Sonic®, Surveil®, Valor® SX, Valor® XLT, or Verdict® + Group 15 herbicide2
  • Pre-Emerge**2,4
    Boundary®, Authority® MTZ, Canopy®, or metribuzin + Group 15 herbicide5
  • Post-Emerge***
    XtendiMax® + glyphosate + Group 15 herbicide2
  • Salvage3
    XtendiMax® + glyphosate

What to consider when developing your management plan

Keep in mind that your management plan should be developed for your specific weed pressures and any resistance issues present. Even when you observe herbicide resistance, remember that there is little chance that your particular weed will be resistant to all the mentioned groups. These herbicides continue to be important control options for many of the weeds we have in the U.S.

What is important is that you rotate your chemistries and crops to most effectively deal with these difficult to control species. ALWAYS READ AND FOLLOW LABEL INSTRUCTIONS. These chemical tables are not specific recommendations that apply to all fields. There is no expressed or implied guarantee of performance from any product listed above.

And, as always, consult your trusted FBN agronomist to design the best herbicide plan for your operation and talk to your FBN account executive about adjuvant options to maximize weed control.

Scout your fields with greater insights

Scouting your fields can give you a good idea of what pressures you're dealing with. You can up your scouting game utilizing precision maps and data specific to your farm and fields. Download our FBN Precision Mapping Guide to find out how.

FBN precision maps can help you evaluate your farm fields

ALWAYS READ AND FOLLOW LABEL DIRECTIONS. It is a violation of federal and state/provincial law to use any crop chemical product other than in accordance with its label. The distribution, sale and use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. It is your responsibility to confirm prior to purchase and use that a product is labeled for your specific purposes, including, but not limited to, your target crop or pest or weed, and its compatibility with other products in a tank mix.
 
* Pre-Plant: 14-21 days before planting
** Pre-Emerge: Before soybean emergence up to 7 days before planting
*** Post-Emerge: 7-21 days after planting

1. Paraquat plus surfactant should be mixed with residual herbicides to control Palmer amaranth and waterhemp emerged before application.
2. All listed residual herbicides for preemergence application contain metribuzin. Some soybean varieties are susceptible to injury from metribuzin. Manufacturer information should be consulted during variety selection for level of metribuzin tolerance. Also be aware of potential plant back restrictions with metribuzin and metribuzin containing products
3. Salvage treatment should target escaped Palmer amaranth and waterhemp not controlled by earlier applications.
4. Some of these options may not be applicable due to the herbicide group resistance present.
5. Examples of Group 15 herbicides include: Dual® II Magnum, Warrant®, or Outlook®
6. With these systems, take note of approved tank mix status for any products used with these herbicide trait systems.
 
Sources: 

https://ag.purdue.edu/btny/weedscience/Documents/BurndownMadness.pdf
https://extension.msstate.edu/publications/programs-for-managing-herbicide-resistant-palmer-amaranth-mississippi-soybean

Authority® is a registered trademark of FMC Corporation. Fierce®, Valor® and Cobra® are registered trademarks of Valent U.S.A. LLC Agricultural Products. Envive®, and Canopy® are registered trademarks of DuPont Crop Protection. LibertyLink®, Outlook®, Sharpen® powered by Kixor® and Verdict® powered by Kixor® are registered trademarks of BASF Ag Products. Enlist E3™ soybeans, Sonic®, Surveil® and Enlist Duo™ Herbicide with Colex D Technology are registered trademarks of Dow AgroSciences LLC.Boundary® and Dual® are registered trademarks of Syngenta Crop Protection, LLC. Ultra Blazer® is a registered trademark of UPL NA Inc. Liberty® is a registered trademark of Bayer CropScience. Roundup Ready 2 Xtend® technology, Warrant® and XtendiMax® With VaporGrip® Technology are registered trademarks of Monsanto Company.