Database Research Summaries
2018 Tillage and other strategies for plyphosate-resistant waterhemp management

calendar_today Year of Research: 2018
update Posted On: 12/04/2019
group Christy Sprague (Principal Investigator, Michigan State University)
bookmark Michigan Soybean Promotion Committee

Research Focus

The focus of this project is to develop and strengthen our current recommendations for control of herbicide-resistant waterhemp.


  • Evaluate the effect of deep tillage on waterhemp populations the following season.
  • Evaluate the effectiveness of several Liberty (glufosinate)-based weed control programs on the management of herbicide-resistant waterhemp in Liberty Link soybean.
  • Develop and evaluate various herbicide programs using dicamba (XtendiMax) in Roundup Ready 2 Xtend soybean for management of glyphosate-resistant waterhemp.
  • Provide this new information on the management of herbicide-resistant waterhemp to Michigan soybean growers.


  1. The initial soil seedbank of waterhemp from greenhouse grow outs from fall collected samples was 20 plants per 4-inch diameter core at the 0 to 2-inch depth and 52 plants at the 2 to 7-inch depth.
  2. Waterhemp emergence in moldboard plowed peaked on June 14, averaging 28 plants per 0.25 m2. Soil-finished and no-till plots peaked one week later on June 21, averaging 19 plants, and 12 plants per 0.25 m2 respectively.
  3. Postemergence follow up applications of XtendiMax (dicamba) and XtendiMax + Warrant (acetochlor) provided excellent control of waterhemp when applied in July.
  4. At the time of the POST Liberty application, 40 DAP, all treatments provided 90% or greater waterhemp control with the exception of: Valor (2 oz), Metribuzin (8 oz), Valor + Metribuzin, and Warrant.
  5. After the POST Liberty application all treatments provided greater than 90% waterhemp control.
  6. Soil-applied applications of Valor at 2 oz/A provided 76-85% control of waterhemp until 40 d after planting (DAP) when the POST herbicide applications were made.
  7. Soybean injury from POST applications only occurred when the active ingredient fomesafen (Flexstar or Warrant Ultra) or lactofen (Cobra) was applied. Injury ranged from 14-23%, 7 d after treatment (DAT).
  8. Waterhemp control 30 DAT was greater than 90% with Liberty and XtendiMax treatments, with the exception of Liberty alone. Waterhemp control was between 80 to 88% when Flexstar or Cobra was applied.


  • This research provides effective information to soybean growers to help manage this troublesome economically significant weed problem.
  • This research provides additional control strategies and herbicide options to aid in the management of a weed that has the ability to develop resistance to multiple-herbicide sites of action.

For more information about this research project, please visit the National Soybean Checkoff Research Database.

Funded in part by the soybean checkoff.