Palmer amaranth

Smooth, hairless stem of Palmer amaranth. Palmer's stems do not have hairs, which is a way to distinguish it from Redroot pigweed, which has fuzzy hairs on the stem.

Smooth, hairless stem of Palmer amaranth. Palmer’s stems do not have hairs, which is a way to distinguish it from Redroot pigweed, which has fuzzy hairs on the stem.

Palmer whisker zoomed

Often, but not always, Palmer amaranth leaves have a small “whisker” or pointed hair on the tip of the leaf.

Herbicide resistant populations:

  • Group 2 + 9
  • Group 2
  • Group 3
  • Group 5
  • Group 9
  • Group 14
  • Group 27
  • Group 9 + Group 14
  • Group 5 + Group 27
  • Group 5 + Group 9

Locations of resistant populations:

Alabama, Arizona, Arkansas, California, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Minnesota, Mississippi, Missouri, Nebraska, New Jersey, New Mexico, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Texas, Wisconsin, Virginia

Resources:

VIDEO: Palmer Amaranth and Waterhemp Identification – From Pigweed Management Video Series – Penn State

The Grim reality of ‘Pigweed Patrol’ – Farm Journal

Video – Palmer amaranth ID and management – Penn State

Palmer amaranth Management in Illinois – University of Illinois

Palmer Amaranth Identification, Biology, and Management – Purdue University

Palmer Amaranth Control – Kansas State University

Palmer amaranth could affect Illinois soybean yield

Up-to-date info from U of Minnesota on the management and spread of Palmer Amaranth in the state

Pictorial Guide for Aid in Identifying Palmer Amaranth and Waterhemp – University of Minnesota

Palmer Amaranth and Waterhemp – New Threats to Pennsylvania Agriculture – Penn State

Detailed Palmer amaranth information – ID and management – Penn State