Iowa

Iowa State University Weed Science: http://www.weeds.iastate.edu/

ISU Palmer amaranth resources:

http://www.weeds.iastate.edu/mgmt/2014/PAresources.html

Herbicide Resistant Weeds in Iowa

Updated October 2016. Source: Bob Hartzler, Iowa State University; www.weedscience.org – Iowa

Reading this list: Each weed with herbicide resistant populations in this state is listed. Underneath each species is a list of the unique resistant biotypes of that weed in the state, according to the herbicide group(s) they are resistant to.

Tall waterhemp – Highest concern

  • Group 2
  • Group 5
  • Group 9
  • Group 14
  • Group 2 + Group 5 + Group 27
  • Group 2 + Group 5 + Group 9 + Group 27

Common cocklebur – Second highest concern

  • Group 2

Common lambsquarters – Third highest concern

  • Group 5

Palmer amaranth – Emerging problem weed

  • Resistance mode of action not yet confirmed

Giant foxtail

  • Group 1
  • Group 5

Pennsylvania smartweed

  • Group 5

Horseweed

  • Group 9
  • Group 2

Giant ragweed

  • Group 2
  • Group 9

Common sunflower

  • Group 2

Kochia

  • Group 5

Shattercane

  • Group 2