Palmer amaranth Bruce Potter, University of Minnesota Extension
ON ALERT: Minnesota Department of Agriculture officials want Minnesota farmers and landowners to keep an eye out for Palmer amaranth, a highly invasive prolific weed that is very difficult to control because it has developed herbicide resistance.

Minnesota’s ‘Palmer Posse’ rides herd to fight Palmer amaranth

MDA’s new Palmer eradication coordinator, new seed lab director, university scientists and interagency and local officials, make weed prevention efforts noteworthy.

It takes a posse to ride herd on Palmer amaranth, one of Minnesota’s prohibited noxious weeds.

Since September 2016, when the first Palmer amaranth plant in the state was confirmed, and through fall 2017, the weed has been found in 43 Conservation Reserve Program plantings in four Minnesota counties — Lyon, Yellow Medicine, Douglas and Todd.

With the help of the seed contractor who identified planted sites in Lyon and Yellow Medicine counties, as well as 14 landowners, 175 acres were burned in spring 2017 and 135 acres were treated in June 2017 with broadleaf herbicides, says Tony Cortilet, MDA’s program supervisor for the noxious and invasive weed program. Season-long scouting also took place, with some mowing and hand-pulling taking place.

In early October 2017, after Palmer was confirmed in Douglas County, the sites were torched. However, the sites in Todd County, due to their location and surrounding vegetation, were not. Cortilet says those locations will be burned this spring. MDA’s investigation and scouting continues in both counties, too.

Palmer amaranth was placed on Minnesota’s Prohibited Noxious Weed Eradication List in 2014, requiring all above- and belowground parts of the plant to be destroyed, and prohibiting its sale and transport. After Palmer was found in Minnesota in late 2016, the ag commissioner listed Palmer amaranth as a Prohibited Weed Seed, meaning that violators of the seed law can be punished by administrative, civil and criminal penalties. He also declared Palmer amaranth to be an agriculture emergency, a directive that still stands.

MN Dept of Ag


NEW TO THE TEAM: The newest member on the Minnesota Department of Agriculture’s “Palmer Posse” is Shane Blair, MDA’s new Palmer amaranth eradication coordinator. (Photo courtesy of MDA)

Team effort
Since the highly invasive weed has been found in Minnesota, state and local agency personnel and university weed scientists have been working to determine the best way to collaborate and control future outbreaks quickly and effectively. Within MDA in St. Paul, Cortilet and weed team colleagues Monica Chandler and Emilie Justen are already responsible for dozens of weeds listed under the state’s Noxious and Invasive Weed law. With Palmer added to the load, the department last summer hired Shane Blair to serve as Palmer amaranth eradication coordinator. Based in Rochester, Minn., Blair is responsible for making field visits to verify weed species.

“It’s extremely helpful that we have a full-time person,” Cortilet says.


Denise Thiede, supervisor, MDA seed and biotech unit

Rounding out the ‘Palmer Posse’ are MDA’s seed and biotech unit, led by Denise Thiede, and University of Minnesota weed scientists Jeff Gunsoles and Roger Becker.

Thiede, who recently joined the MDA department, provides leadership to the seed unit that is responsible for sampling, testing and monitoring statewide native seed sales and plantings. Gunsoles and Becker have been instrumental in providing outreach and consulting with growers. And at the local level, county and city boards have inspectors that add another level of assistance as well as enforcement.

“MDA is really working hard on directing the eradication on the ground,’ Cortilet says. “Once Palmer amaranth is found, it gets documented, assessed and treated.”

With the weed seed thus far traced back to entering Minnesota via native seed plantings, several state and federal agencies have joined MDA, forming an interagency group to work on minimizing the weed’s impact. Staff from the Minnesota offices of USDA’s Natural Resources Conservation Service and Farm Service Agency, the state departments of Transportation and Natural Resources, the Board of Water and Soil Resources, plus non-profits that use native seed for restoration projects, are participating.

“We’re bringing together all the players, and asking how and what we can do to prevent future Palmer outbreaks,” Cortilet says.

Big jump in seed sampling, testing
Thiede says with their work at the seed unit on Palmer, they’ve had to focus more on sampling native seed mixes. In previous years, the unit may have handled 10 to 30 samples. Last year, unit members examined closer to 200 native seed samples. Those samples were taken from companies that produce seed in Minnesota, from companies that blend and relabel mixes for conservation plantings, and from seeding contractors when seed was being planted. State and federal agencies contacted the seed unit to let them know when contractors were sowing conservation plantings so seed unit inspectors could take samples.

“We want to further build on this collaboration of interagency work in 2018,” Thiede says. “We also want to see established conservation plantings to verify what is coming up. A lot of time, people don’t know if the plants growing are what should be there.”

Thiede also is working at making lab testing and reporting Palmer amaranth discoveries more consistent across the state. Currently, not all labs report if Palmer is found in a seed mix. They may simply say the seed may have been found.

“We need testing labs to report a specific way, and to use genetic testing to verify presence,” she says. Plus, seed purity noxious exams, currently done at harvest and carried forward to the next year, should be conducted again at the beginning of every year.

Legislation will be proposed this coming session that will clarify seed testing requirements and require genetic testing for prohibited noxious weed seed.

“We’re trying to identify deficits [in seed purity testing] and drive changes that are needed,” Thiede says.

The year ahead
Looking ahead to this spring, Cortilet says the weed team will continue to scout for Palmer in all four counties where it has been found, and then create priority areas for further scouting efforts throughout the season. Sites with no visible Palmer will continued to be scouted, but less frequently. Sites with minimal Palmer plants may only be torched, spot-sprayed or hand-pulled.

“If we find sites with a lot of Palmer, they will need to be broadcast-sprayed — or spot-sprayed, depending on what the distributions look like,” he says. In Todd County, the Conservation Corps has been contracted to conduct spring burning on affected sites.

“We’ve already worked with the landowner to cut firebreaks this past fall so that burning can begin immediately when conditions are right,” he adds.

Ongoing vigilance
Cortilet says he expects Palmer amaranth to continue to come into Minnesota, given how easily it can be transported via humans, manure and machinery. He offers four tips for farmers to remember from this growing season forward:

• Make sure you buy seed from a reputable source. “There are a lot of good native seed growers in Minnesota,” Cortilet says. To locate one, contact your local soil and water conservation district for a referral. Don’t hesitate to ask seed sellers about seed sources and guarantees.

• If you bring equipment into Minnesota from out of state, make sure it is very clean.

• Learn what Palmer amaranth looks like. Information can be found on MDA’s website, U-M Extension and via Google. Check out MDA's website and various links about Palmer amaranth.

• If you suspect a Palmer amaranth plant, contact U-M Extension or MDA immediately.

Adds Cortilet: “The more that people know about Palmer, the better.”

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