Weed of the Month: Waterhemp

  • waterhempVarious types: Common1
  • Scientific name: Amaranthus rudis1
  • Member of the pigweed (Amaranthaceae) family1
  • Grass or broadleaf: Broadleaf
  • Commonly found in Midwest states — native to North America1
  • Growing period: mid-May to early July3
  • Plants are male or female2

Fast facts:

  • Waterhemp can reduce yield by 74 percent in corn and 56 percent in soybeans if left unmanaged, according to Wisconsin Crop Weed Science, University of Wisconsin-Madison.1
  • Female plants produce 250,000 seeds per plant. However, one plant can produce up to 1 million seeds if there is little to no plant competition.2
  • Waterhemp can grow between 1 and 1.25 inches per day during the growing season, which is faster than most crops or weeds.2
  • Waterhemp seeds must be in the top inch of soil to successfully germinate and emerge.3
  • Waterhemp is a “multiple herbicide-resistant weed,” which means it cannot be controlled by at least two or more herbicides with different sites of action applied at labeled rates.4

Resistance Statistics:*

According to WeedScience.org:

As of June 2018, herbicide-resistant waterhemp has been reported in the following 18 states, listed in alphabetical order:

  • Arkansas, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, Oklahoma, South Dakota, Tennessee, Texas, Wisconsin

Managing waterhemp:

  • Tillage can help lower waterhemp populations because the seeds must germinate in the top part of the soil; however, tillage may not be a viable method of control on land prone to erosion.3
  • Narrower row spacing can help suppress waterhemp growth.3

Andy Asbury, field scientist, Corteva Agriscience, Agriculture Division of DowDuPont, Dow AgroSciences, offers advice:

  • Farmers should scout throughout the growing season to identify waterhemp early. This helps farmers plan timely herbicide applications and identify potential problem fields for the following year.
  • The best strategy to control waterhemp involves combining aggressive tillage and a program approach to herbicide application — including soil-applied herbicides followed by postemergence herbicide(s) with multiple, effective modes of action. Ideally, you would overlap preemergence residuals and postemergence residuals to reduce the number of germinating waterhemp plants.

Corteva Agriscience, Agriculture Division of DowDuPont, offers the following weed control solutions:

Corn

DuPont Cinch® ATZ herbicide
DuPont Realm® Q herbicide
Durango® DMA® herbicide
Elevore herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
FulTime® NXT herbicide
Keystone® LA NXT herbicide
Keystone® NXT herbicide
Resicore® herbicide
SureStart® II herbicide

Soybean

Durango® DMA® herbicide
Elevore herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
DuPont EverpreX® herbicide
DuPont Trivence® herbicide
FirstRate® herbicide
Sonic® herbicide
Surveil® herbicide

Additional information:

For more information, read these weed science resources:

  1. Butts, T. R., and V. M. Davis. 2014. Preliminary data suggests glyphosate resistance of two Wisconsin common waterhemp (Amaranthus rudis) populations. https://wcws.cals.wisc.edu/tag/amaranthus-rudis
  2. Bechman, T. J. 2017. 8 facts you should know about waterhemp in Indiana. http://www.indianaprairiefarmer.com/weeds/8-facts-you-should-know-about-waterhemp-indian
  3. Pioneer. Effective Management of Waterhemp. https://www.pioneer.com/home/site/us/agronomy/waterhemp-mgmt-soybean
  4. Ganie, Z., and J. Amit. Multiple Herbicide-Resistant Weeds and Challenges Ahead. https://cropwatch.unl.edu/multiple-herbicide-resistant-weeds-and-challenges-ahead

®™Trademarks of Dow AgroSciences, DuPont or Pioneer and their affiliated companies or respective owners. DuPont Cinch® ATZ, FulTime NXT, Keystone LA NXT and Keystone NXT are federally Restricted Use Pesticides. DuPont Cinch® ATZ herbicide, DuPont EverpreX herbicide, DuPont Realm® Q herbicide, DuPont Trivence® herbicide, Durango DMA, Elevore, FirstRate, FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore, Sonic, SureStart II and Surveil are not registered for sale or use in all states. FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore and SureStart II are not available for sale, distribution or use in Nassau and Suffolk counties in the state of New York. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Enlist Duo and Enlist One herbicides are not registered for sale or use in all states or counties. Contact your state pesticide agency to determine if a product is registered for sale or use in your area. Enlist Duo and Enlist One herbicides are the only 2,4-D products authorized for use in Enlist crops. Always read and follow label directions. ©2018 Corteva Agriscience