Virginia

Weed scientists at Virginia Tech track herbicide resistant weed populations in the state and provide integrated weed management recommendations for these and other weeds. They also maintain an online weed identification guide.

Virginia Tech Newsletters for Plant Pathology, Physiology, and Weed Science: http://www.ppws.vt.edu/news/newsletters.html

In 2015-16, Virginia Tech conducted surveys throughout the state to track the distribution of three problem weeds: Palmer Amaranth, common ragweed, and marestail. These are shown in the maps below:

Slide2 Virginia county map Palmer 2016Slide3 Slide4

Herbicide resistant weeds in Virginia

Updated Oct. 19, 2016, Source: Michael Flessner, Virginia Tech; www.weedscience.org – Virginia

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

  • Group 2
  • Group 9
  • Groups 2 + 9

Horseweed/marestail

  • Group 2
  • Group 9
  • Groups 2 + 9

Common Ragweed

  • Group 2
  • Group 9
  • Groups 2 + 9

Annual bluegrass

  • Group 5

Chickweed, common

  • Group 2

Italian ryegrass

  • Group 1

Johnsongrass

  • Group 1

Lambsquarters, common

  • Group 5

Redroot pigweed

  • Group 5

Smooth pigweed

  • Group 2
  • Group 5

Shattercane

  • Group 2