Palmer amaranth

Palmer amaranth, the very aggressive, hard-to-control weed first found in a row-crop field in McIntosh County this summer has been confirmed in four more North Dakota counties: Benson, Dickey, Foster and Richland. Plants in two counties were confirmed through laboratory analysis and NDSU Extension specialists confirmed the plants as Palmer amaranth in the other two counties.

The office of agriculture commissioner, Doug Goehring, as well as NDSU Extension have been working to develop a plan for the state’s producers to help control, and hopefully eradicate the weed.

“A lot of farmers I’ve spoken to thought they had to be on the lookout, some were concerned, and others seemed as though they discarded it and thought there was maybe too much hype around it. Now that (Palmer amaranth) is here, there’s certainly been a heightened awareness that this is a concern and a problem. You don’t want this thing established.”

Goehring went and saw the plant for himself down in Richland County.

“It was like a tree,” he said. “It looked like an arm of an individual, and it only had one season to grow. It grew 12 feet tall and stretched out 10 feet across. That is a heck of a plant.”

The way Palmer amaranth reached each county was different. The likely sources were seeds carried by migratory birds, a used combine, an alternative feed source purchased out of state, custom combining and grain cleaned out of railroad cars.

Goehring says their efforts are going to be to continue communicating with farmers to help prevent the weed from continuing to spread across the state.

“If you’re buying equipment from out of state or if you have a custom harvester come in, please look at cleaning up that equipment as good as you possibly can before it comes into the state,” he said. “Secondly, whenever you have equipment or a custom harvester, monitor those fields, scout them hard and continue to do that throughout the growing season.”

The Palmer amaranth seed can germinate early in the spring, late in the spring, or early in the summer, meaning different herbicide options are necessary to fight it.

“We saw it this year and it’s amazing how prolific and aggressive this plant really is,” said Goehring. “We have got to stop relying so much on Roundup or glyphosate. It was never intended to be a broadleaf herbicide. I know it controlled things and works well on grass, but you need to be looking at other chemistries. We also need to be thinking about next year’s crop rotations, and weed management strategies, which could be pre-plant or pre-emerge, but we definitely need to have that as part of the equation and not just solely rely on post-emergent herbicides.”

Contaminated seed, wildlife, water and wind are among other ways Palmer amaranth seeds can spread. Other sources include potting soil, hay from other states and native seed mixes used for pollinator or wildlife habitats.

Because Palmer amaranth resembles other pigweeds, it can also be difficult to identify. Once someone contacts Extension about suspected Palmer amaranth, an Extension agent or specialist, or both, visit the field and investigate to determine what it is. If necessary, they also send samples to the University of Illinois Plant Clinic for DNA testing. Lab results take about two weeks.

While some farmers may have disregarded the impact Palmer amaranth could have, that tone has quickly shifted to concern. How can they handle it? How can they deal with it? And for the ones where it’s happened in their area, what do they have to do?

“The most unlikely places are now the areas you have to be looking,” said Goehring. “Chances are if you put weed management strategies in place, you’ll hopefully control and eradicate it in your field. It’s the edges of the field, the ditches, the ravines, drainage areas, creeks, streams, or around wetlands where you’re most likely to see it.”

To help producers, landowners and other learn more about Palmer amaranth and how to spot it, NDSU Extension has developed a website: https://www.ag.ndsu/edu/palmeramaranth.

“We need to work and get as much info out as we can. The reality is that state and federal laws state that noxious weeds are the responsibility of the landowner,” said Goehring. “So we’re trying to provide many tools back to the landowner so they can scout, manage and look for it, control it and eradicate it. Make us aware if you have a suspect case. Let us know and let NDSU know. We’ve been working on this thing together to make sure we have the proper protocols in place. We don’t want to have panic, but we need to have concern.”