Palmer amaranth, considered by some experts to be the most dangerous weed in America, continues to spread in North Dakota. It's now been found in 12 counties, with two more infestations — in Cass and Barnes counties — announced Wednesday, Sept. 9.

But that's no reason to be discouraged or to slack off in efforts against the weed, which can ravage crop yields, said Joe Ikley, North Dakota State University extension weed specialist.

"It's better that we're finding it in these counties. People are out looking for it, so we're finding it early and we're able to start controlling it. That's better than it being in those counties and us not finding it," he said.

In Barnes County, a crop specialist noticed some suspect plants in a field and notified the landowner, who worked with an NDSU specialist. In Cass County, an Extension specialist found it within the city of Fargo, the state's largest city. In both cases, samples were submitted for DNA analysis to the National Genotyping Center, where they were confirmed as Palmer, according to the state ag department.

Landowners involved in the 12 infestations have not been identified publicly, other than by county. Ag officials say that releasing the names of landowners might discourage others from reporting suspicious plants.

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Palmer was found along a street in an industrial area in north Fargo, Ikley said.

The weed can establish itself in many places besides cropland, so everyone has a role in fighting Palmer, he said.

A Palmer amaranth plant in a conservation planting. Minnesota Department of Agriculture photo.
A Palmer amaranth plant in a conservation planting. Minnesota Department of Agriculture photo.

The state ag department Sept. 4 said that Palmer amaranth had been confirmed in Stutsman County. A county weed officer noticed suspect weeds in a field, notified the landowner and then worked with NDSU. DNA samples confirmed it was Palmer.

The Stutsman infestation was the second finding of Palmer in North Dakota this year; the weed also was found earlier in 2020 in Benson County. Palmer first was found in the state in 2018 and now has been identified in 12 counties.

From the beginning, ag officials familiar with the weed stressed that keeping Palmer out of the state altogether would be virtually impossible. As Ikley said, the goal has been identifying infestations early and then getting them under control.

"The main goal is to find it early and eliminate the plants that can go to seed." he said. "It can be managed long term. As long as we stay on top of infestations, it's certainly manageable."

It appears that the infestations identified so far in North Dakota were caught early enough that they can be controlled, Ikley said.

Palmer amaranth, which already has been found in Iowa, Minnesota and South Dakota as well as North Dakota, can damage farm equipment and devastate yields. Yield losses of up to 91% in corn and 79% in soybeans have been reported.

Why it's so feared

Palmer is dangerous and difficult to control for a number of reasons, including:

  • A single plant can produce as many as 1 million seeds.

  • The seeds are extremely small and farmers can spread them unintentionally.

  • Seeds can lie dormant in the soil for years, waiting to germinate until growing conditions are favorable.

  • It can grow up to 3 inches per day and is unusually competitive with most crops, including corn and soybeans.
  • It develops resistance to herbicides relatively quickly.

  • Migratory birds can eat Palmer seed in one state and carry it hundreds or even thousands of miles.
  • It can be easily mistaken for several other weeds.

Report suspicious plants

Anyone spotting a suspicious plant in North Dakota or another state should contact the state extension service or ag department. In North Dakota, go to https://www.nd.gov/ndda/pa.

The North Dakota Department of Agriculture has more information on Palmer and other noxious and invasive weeds at https://www.nd.gov/ndda/plant-industries/noxious-weeds.