National Agricultural Genotyping Center lab sets sites on Palmer amaranth
A genetic testing laboratory located the campus of North Dakota State University in Fargo provides diagnostic testing for Palmer amaranth, a specially invasive and destructive noxious weed.
FARGO, N.D. — A sophisticated genotyping laboratory in Fargo is likely to become more popular for agronomists and others for fast confirmation of Palmer amaranth weed infestation And now, it can determine whether the seeds or weed leaves show resistant to either glyphosate or Group 14 herbicides.
The National Agricultural Genotyping Center, located at the back of a U.S. Department of Agriculture laboratory just west and south of the Fargodome on the North Dakota State University campus, has been open since 2016. It has recently set up to confirm Palmer amaranth weeds and in 2022 was fully ready to test for herbicide-resistance.
Palmer amaranth confirmation tests numbers are rising: 81 in 2019; 60 in 2020; 473 in 2021, and 380 through Aug. 31, 2022. If the submitter is confident a weed is waterhemp and wants just the two herbicide-resistance tests, the cost is $75 plus $20. Turnaround time for regular testing is 5-10 business days, rush is 3 business days or less, for double the cost.
Quick look back
The NAGC started as a joint project between the National Corn Growers Association and the Los Alamos National Laboratories. Today, much of its funding comes from the North Dakota Department of Agriculture, North Dakota Soybean Council, the North Dakota Corn Utilization Council.
The lab’s job is to create ag-related diagnostic tests — genetic tests to help farmers with pest and pathogens in agriculture. The first tests were for 15 pathogens in honeybee colonies. They have since expanded into crop diagnostics and weed identification.
Zack Bateson, is the lead research scientist at the lab. In 2018, the lab started a test that was able to confirm that a weed seed or plant tissue is or is not Palmer amaranth — a weed that is dangerous.
By 2019, they were providing the service for North Dakota, South Dakota, Montana, and Idaho state agencies and university researchers. Minnesota has its own lab. Researchers and even some growers have asked for the tests. “We offer this test to anyone who wants particular pigweeds identified in a sample,” he said.
The NAGC also is well known for testing for pathogens in corn — northern corn leaf blight , gray leaf spot . They are a part of a national program called the National Predictive Modeling Tool Initiative.
“We have universities across the U.S. that looking at fungal pathogens in corn, cotton and wheat,” Bateson said. The other universities have test plots and go out to collect samples — things like soil, residue, or spore traps. “We are performing the DNA extraction and identifying the particular pathogens,” he said.
The lab is playing a key role in the fight against Palmer amaranth.
The weed is a unique threat. It can grow to eight tall, producing 1 million seeds per plant, and can germinate throughout a season. It is in the pigweed family, and difficult to distinguish from less problematic cousins. Populations somewhere in the country have shown resistance to glyphosate (Roundup) and other common herbicides.
Initially, the lab worked with the North Dakota State Seed Department to identify Palmer amaranth seeds within wheat seed samples being studied for certification. The state seed department tested for purity but didn’t have the capability of distinguishing among the small, black “amaranth” seeds, which includes waterhemp and pigweed.
They also acquired “confirmed” herbicide-resistant seed samples from North Dakota State University Extension. NAGC can identify a single Palmer amaranth seed within a group of 200 redroot pigweed seeds. Most of the samples are seeds, but they can also identify Palmer amaranth from leaf tissue.
In 2018 the NAGC started to positively identify Palmer amaranth within certain crop seed mixtures.
By 2021, they were refining a herbicide-resistance test for whether a sample has markers for resistance to glyphosate or Group 14 herbicides. In 2022 started making it more commercially available.
Joe Ikley, an NDSU Extension weed specialist, predicts Group 14 verification will become important. To grow seeds and spray them with the herbicides in a greenhouse is a six- to ten-week process. The NAGC can do it much more quickly.
An NDSU survey last fall and winter found some herbicide-resistant pigweed in 16 North Dakota counties. Pigweed includes several species — waterhemp, Palmer amaranth, redroot pigweed, Powell amaranth, and tumble pigweed. The project targeted whatever pigweed survived management on either soybean or dry edible bean fields.
Not surprisingly, every waterhemp sample in the survey was glyphosate-resistant. These were counties with a high proportion of soybeans. Ikley said it’s important to have the laboratory for resistance to glyphosate and Group 14 or PPO (Protoporphyrinogen oxidase inhibitor). They found PPO-resistance in seven counties.
When to check
“If you have questions about Group 14 resistance, collect samples to send in,” Ikley urged. "With Group 14 waterhemp and Palmer amaranth resistance, there is still some control from soil residual herbicides like Spartan (sulfenzatrone) but we have less control — to two weeks instead of four weeks. On a population that is not resistant, control could last four to six weeks."
Ikley urges farmers and agronomists to keep an eye out if waterhemp weeds emerge sooner than expected after a pre-emergence PPO herbicide. Those plants perhaps should be tested. Knowing for sure the farmer has resistance will indicate using a different mode of action to clean up escapes.
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“A lot times we might be scouting a field 7 to 14 days after a post-emergence herbicide application,” Ikley said. “If we have some plants survive that might be a good time to collect a sample and see if that if it’s resistance, or that didn’t work for another reason.”
Most agronomists know whether they are dealing with Palmer or waterhemp. If the sender doesn’t know which pigweed is being tested, the lab could identify whether it is Palmer or waterhemp. Bateson said the lab so far has shown Group 14 (PPO-inhibitors) resistance only in the waterhemp, not the Palmer amaranth.
Ikley noted Palmer amaranth in the tests primarily have come from NDSU where they’ve worked with the North Dakota Department of Agriculture to discover and confirm, including cases in Spiritwood, North Dakota, and Shields, North Dakota.
“It’s usually been animal feed with millet fields or sunflower screenings,” Ikley said.
The Palmer amaranth confirmation rate is connected to where the sunflowers in the screenings “originated” These likely are not sunflower seeds from North Dakota, but from the southern Great Plains, and likely from Corn Belt and Cotton Belt states — where they have Group 14 resistance. Sunflower seeds from Texas and Kansas tend to have less resistance because those regions are less reliant on Group 14 herbicides, he said.
Agronomists and co-ops will be the most interested in the testing, Ikley predicted, especially to problem-solve if weeds escape the recommendations they’ve made.