Managing Herbicide-Resistant Palmer Amaranth Field Day

Depictions of Palmer amaranth in corn
Figure 1. (L) Palmer amaranth in corn and (R) a Palmer amaranth seedling. A member of the pigweed family, Palmer amaranth is a difficult to control broadleaf made even more difficult by its growing resistance to herbicides, including atrazine and HPPD inhibitors.

Managing Herbicide-Resistant Palmer Amaranth Field Day

Learn how to get an edge on managing Palmer amaranth resistant to atrazine and HPPD-inhibitor herbicides Tuesday, Aug. 4 at a Nebraska Extension field day near Shickley.

Curtis Thompson
Curtis Thompson

Experiments at the Herbicide-Resistant Palmer Amaranth Management Field Day will demonstrate how to control resistant Palmer amaranth in field corn and seed corn production. Palmer amaranth resistant to atrazine and HPPD-inhibiting herbicides such as Callisto and Laudis is of particular concern in south central Nebraska where the seed corn industry relies heavily on these herbicides for weed control.

Keynote speaker will be Curtis Thompson, professor of weed science and State Extension Agronomy Leader with Kansas State University. Thompson was the first to confirm atrazine- and HPPD inhibitor-resistant Palmer amaranth in Kansas and researches field management options.

Tour Topics

The field day tour will include sites demonstrating various weed management practices:

  • Dose response of Atrazine, Callisto, Corvus, and Balance Flexx applied pre-emergence to Palmer amaranth in field corn
  • Tank mixing atrazine with Callisto or Balance PRO at different rates for control of Palmer amaranth
  • Tank mixing atrazine with Callisto, Laudis, or Armezone applied post-emergence for control of Palmer amaranth
  • Herbicide programs for resistant Palmer amaranth control in seed corn
  • Management of Palmer amaranth in Roundup Ready Corn and Liberty Link Corn
  • Evaluate programs of Corvus or Balance Flexx followed by DiFlexx in Roundup Ready corn
  • Understanding emergence of Palmer amaranth for most effective control
  • Understanding effect of tillage on Palmer amaranth emergence
  • Overlapping residual herbicides for Palmer amaranth control in field corn

Directions to the Field Day: From Geneva go south on Hwy 81 for 7 miles. Turn west onto Hwy 74 for 12 miles. Turn north on Road 2 for 3 miles. Turn west on Road Q for 0.1 mile. Farm field is located on the north side of Road Q.

Preregistration and Resources

Preregistration is required by noon on Aug. 3 at

The event will begin with registration at 8:30 a.m., followed by a program from 9 a.m. to 1:30 p.m. Lunch is free and will include UNL Dairy Store ice cream

Three CCA credits will be available.

For more information, see program flyer or contact Amit Jhala, Nebraska Extension Weed Management Specialist, at 402-472-1534 or

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A field of corn.