Minnesota Soybean Business

MN AG EXPO 2019: The Palmer amaranth battle

Agricultural scientists and researchers met their match with Palmer amaranth ever since the invasive weed was first located in 33 locations in Minnesota in 2016.

“It’s an extremely aggressive growing weed and has incredible genetic diversity,” says Minnesota Soybean Director of Research David Kee. “Palmer amaranth is certainly a problem we don’t need in Minnesota.”

At the 2019 MN AG EXPO, farmers can visit the Research and Innovation Center (located on the second floor of the trade show) and meet with Kee and University of Minnesota specialists to learn the most effective ways to combat and identify Palmer amaranth. Additionally, researcher Andrew Lueck will deliver a waterhemp resistance presentation sponsored by the Minnesota Soybean Research & Promotion Council that, along with other checkoff-funded projects, will be used to develop a Palmer amaranth control system.

“The team of researchers and University extension staff at MN AG EXPO will be able to answer any questions on Palmer,” Kee says. “We’re excited to talk with growers about best management practices on their land.”

Farmers, not researchers or regulatory officials, hold the key to identifying and ultimately eradicating Palmer amaranth, says Minnesota Department of Agriculture noxious weed and invasive weed supervisor Anthony Cortilet.

“We’re just trying to bring awareness, but farmers will be the ones who solve the problem,” Cortilet says. “The farmers are the ones who have stepped up and found every single one of the locations. They’re the ones who are going to end up stopping it, and we really need their help.”

Native to the southwestern United States and northwestern Mexico, Palmer amaranth is a dioecious (has male and female plants) annual with high seed production (estimated up to ½ million/plant). Young (less than 2 inches tall) Palmer can be easily confused with other pigweeds. During optimal conditions, it has an extremely fast growth rate (measured in inches per day) and has developed resistance to several important herbicide groups. Crop loss has been documented to exceed 65 percent, dependent on weed population and pressure.

During the fall, a limited number of Palmer amaranth plants (two females and three males) were discovered for the first time in Minnesota row crop sites. Two soybean fields in Redwood and Jackson counties were found to contain Palmer amaranth. It is currently thought this weed was transported to the sites via contaminated products or equipment. Once confirmed, all these plants were destroyed; no Palmer amaranth seed was discovered on either site.

“We’ve done a lot of scouting and spring burns and hand pulling,” Cortilet says. “We have found no reoccurrences of Palmer amaranth, so it looks like our efforts are paying off.”

Early detection is extremely crucial in preventing Palmer’s spread. If farmers spot Palmer amaranth on their field, they should notify their crop consultant, an extension professional or an MDA official immediately. All sightings are kept confidential. MDA also has a staff member whose sole focus is dedicated to responding to Palmer amaranth findings.

“The best thing to do is leave it alone, mark where it’s at, and make sure you know how to get back to it and report it,” Cortilet says. “We’re not going to turn it into a three-ring circus. We’re trying to protect the farmer best we can because this is becoming more common.”


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