Pennsylvania

Herbicide resistant weeds in Pennsylvania

Updated October 21, 2016. Bill Curran, Pennsylvania State University; www.weedscience.org – Pennsylvania

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.

Palmer Amaranth – Highest concern

  • Group 9 (glyphosate)
  • Group 2 (ALS)

Waterhemp – Highest concern

  • Group 9 (glyphosate)
  • Group 2 (ALS)

Horseweed – Third highest concern

  • Group 9 (glyphosate)

Lambsquarter

  • Group 5 (atrazine)

Smooth pigweed

  • Group 5 (atrazine)

Redroot pigweed

  • Group 2 (ALS)
  • Group 5 (atrazine)

Shattercane

  • Group 2 (ALS)

Giant foxtail

  • Group 2 (ALS)

Common ragweed

  • Group 9 (glyphosate)

Common chickweed

  • Group 2 (ALS)