The National Agricultural Genotyping Center (NAGC), located on the North Dakota State University (NDSU) campus in Fargo, N.D., aims to improve diagnostic services in the agricultural community. 

“There is a testing gap when it comes to diagnostics in agriculture compared to human diagnostics and even livestock,” said Zack Bateson, Ph.D., research director of the NAGC. “NAGC is trying to close that gap by helping to diagnose pests and identifying traits within crops, as well as honeybees.” 

New this year, the Minnesota Soybean Research & Promotion Council is working with the NAGC on an herbicide resistant weed survey. 

While the survey itself is not new, this is the first time Minnesota is participating. 

“Around 2019 is when our weed diagnostics started,” Bateson said. “We were approached from the North Dakota State Seed Department about the inability to identify amaranth species by seed size and shape.” 

There are many varieties of amaranth, including commercially grown edible varieties, but Palmer amaranth is one of the most economically damaging weeds for farmers. This invasive weed competes aggressively with row crops and spreads exponentially. Each plant can produce more than 250,000 seeds. It can also be resistant to multiple herbicides, including glyphosate. 

“It was Palmer amaranth that drove our interest into weed diagnostics,” said Bateson. “We developed a genetic test to confirm amaranth species during seed lab purity tests, which is sensitive enough to detect a single Palmer amaranth seed among a pool of 200 amaranth seeds.” 

Fast forward to 2023, and interest grew in testing for herbicide resistant weeds. The NAGC jumped on the opportunity and began collaborating with NDSU weed scientists to validate genetic tests by sampling weeds from greenhouse herbicide trials. 

“There’s a lot of genetic markers associated with herbicide resistance in multiple weed species,” said Bateson. “We’re able to use this genetic test to have folks send us leaf samples and test for these markers associated with herbicide resistance so they can use that information in-season for a different herbicide approach or different weed management approaches.” 

The program currently tests for resistances to herbicide groups 2, 9 and 14, which covers ALS inhibitors, EPSPS inhibitors (glyphosate) and PPO inhibitors. 

“When it comes to herbicide resistance, there are two flavors,” Bateson said. “There are non-target site mechanisms, where the weed can isolate or metabolize the herbicide before it becomes active and inhibits the plant. The second is target site mechanisms – the genetics. We can look for these point mutations in the genome that allow the plant to escape herbicide action.” 

The NAGC has reached the point where they know the exact gene mutation that leads to herbicide resistance, specifically for pigweeds like Palmer amaranth and waterhemp. It does get more complicated, and there can be several point mutations that can lead to resistance, but they are currently focusing on one per herbicide group. 

Grower participation 

With support through various commodity groups, and now MSR&PC and the soy checkoff, the NAGC has created collection kits that farmers can request to send in their weed samples for testing. Each kit comes with a prepaid business envelope that contains four coin envelopes, a submission form and a collection guideline. Three of these envelopes are for one variety of pigweed, including waterhemp, Palmer amaranth or kochia, and the fourth is for grassy weeds. 

“We’re looking for wild oat and green foxtail to develop new tests,” Bateson said. 

After receiving the samples and testing for resistance, Bateson and the NAGC team aggregate that information into county-level weed maps.  

“Even if farmers don’t participate in the survey, they’ll be able to see if their county or a neighboring one contains weeds with herbicide resistance,” Bateson said.  

To request a sample kit, contact MSR&PC Research Director Sergio Cabello Leiva at scabelloleiva@agmgmtsolutions.com or the NAGC at genotypingcenter.com.