Palmer amaranth (Amaranthus palmeri) has invaded the fields of North Dakota. Recognized as one of the most yield-robbing weeds in agriculture, the North Dakota Department of Agriculture wasted little time adding Palmer amaranth to the noxious weed list. Concern over its devastating effects has made the weed a popular topic at ND expos and conferences. One common theme during these discussions was to inform growers on how to differentiate Palmer amaranth from other ND pigweeds, specifically Waterhemp (A. tuberculatus). The window of opportunity for effective herbicide treatments is limited to shortly after emergence, and before the weeds reach 3 inches. This early detection in the field can mean the difference between shutting down an early infestation and a permanent increase in annual herbicide to curtail an established population of this highly productive weed.
Palmer Amaranth (North Dakota State University Photos)
Unfortunately, visual identification at the vulnerable and early stage is challenging for even the most experienced weed scientists. Moreover, nature is not always textbook, making it difficult to fully document the overwhelming variation among individual Palmer amaranth plants, which can arise from the field or regional differences in soil types, nutrient loads, and water availability. As a result, photographs that are used to help growers differentiate amaranth species can fall short, potentially causing further confusion and inadequate control recommendations.
Thus, the most reliable way to confirm Palmer amaranth and other pigweed species is to supplement the visual diagnosis with a DNA test. Since identification is difficult and effective control is time-dependent, the National Agricultural Genotyping Center (NAGC) partnered with weed scientists at North Dakota State University to make a rapid DNA test available to the agricultural community.
This project was funded in part by the North Dakota Corn Utilization Council. Read the latest research update from NAGC here.
To collect weed samples and submit them for identification, please use the forms below or visit the National Agriculture Genotyping Center (NAGC) webpage for more information.
Sample Collection and Submission Instructions – Palmer amaranth
GENERAL SAMPLE SUBMISSION FORM
Additional Resources:
Pigweed Awareness Campaign:
Increasing Awareness and Risk of Palmer amaranth and Waterhemp in ND
Introduction: Palmer Amaranth Update – Joe Ikely, Extension Weed Specialist, NDSU
Palmer amaranth – recognized as the most problematic weeds in the United States – has invaded North Dakota fields. Palmer amaranth is a troublesome weed because it grows and reproduces rapidly and prolifically; it is prone to develop resistance to multiple herbicides. It can dramatically cut crop yields, too. In this video, Assistant Professor/Extension Weed Specialist Dr. Joe Ikley from NDSU provides an update on what we know about Palmer Amaranth in North Dakota.
Conclusion: Management Considerations for Palmer Amaranth – Joe Ikely, Extension Weed Specialist, NDSU
Management considerations for palmer amaranth:
1. Exclude or keep palmer amaranth out of production fields.
2. Scout regularly and hand weed to remove suspicious palmer-looking plants from the field.
3. If palmer amaranth needs to be controlled with herbicides, start with effective pre-emergence herbicides regardless of the crop type. Use 2-3 effective active ingredients in that pre-emergence herbicide program.
4. Follow up with the timely application of post-emergence herbicides when palmer amaranth is 1-2 inches tall. Once palmer amaranth is over three inches, the failure of many herbicide programs will occur.
For questions, please contact NDSU’s Dr. Joe Ikley at www.ndsu.edu/agriculture/ag-home/directory/joe-ikley.
For more information about weed management from NDSU, visit www.ag.ndsu.edu/weeds.
To download NDSU’s 2022 Weed Control Guide, visit www.bit.ly/NDSU2022weedguide.
