Palmer amaranth detected in Minnesota

 ST. PAUL, Minn. – Crop scientists at the University of Minnesota and officials at the Minnesota Department of Agriculture (MDA) urge farmers to check fields for Palmer amaranth, an aggressive weed that can put corn and soybean crops at risk. A plant detected in a native seed planting plot on a Yellow Medicine County farm was confirmed today to be Palmer amaranth. This is the first confirmation of the weed in the state.

The MDA asks possible infestations to be reported by contacting the MDA’s Arrest the Pest line by phone at 1-888-545-6684 or by email at arrest.the.pest@state.mn.us. Landowners are encouraged to email photos of suspected infestations for identification.

“We encourage landowners to scout fields now before harvest for Palmer amaranth and report any possible infestations to the Minnesota Department of Agriculture,” said Geir Friisoe, MDA’s Director of Plant Protection. “The quicker we’re able to identify and start managing this weed, the better our chances will be to minimize the impact to our ag industry.”

Palmer amaranth

Palmer Amaranth has been found in Minnesota and the Department of Agriculture wants farmers to keep an eye on their fields to help nip this in the bud before an infestation can occur. (Photo by Bruce Potter)

 

Palmer amaranth can grow 2 to 3 inches a day, typically reaching 6 to 8 feet, or more, in height. Left uncontrolled, a single female Palmer amaranth plant typically produces 100,000 to 500,000 seeds. It is resistant to multiple herbicides.

It has been found in 28 other states, including Iowa, South Dakota, and Wisconsin.

“Palmer amaranth infestations have caused substantial yield losses and greatly increased weed management costs in cotton, soybeans, and corn in the southern states,” said Extension agronomist and crops leader Jeff Gunsolus. “This is a disconcerting, though not completely unexpected, discovery in Minnesota. We have been discussing proper identification procedures with crop consultants over the last three or more years.”

Close-up of Palmer amaranth

Palmer Amaranth has been found in Minnesota fields and it’s important for farmers to watch their fields in order to avoid an outbreak in farm fields across the state. (Photo by Bruce Potter)

 

Extension and MDA officials commend the grower and crop consultant who quickly contacted Extension after discovering a suspected Palmer amaranth plant. The weed is on MDA’s prohibited-eradicated noxious weed list, requiring all above- and below-ground parts of the plant be destroyed. Transportation, propagation or sale of the plants is prohibited.

MDA and Extension continue coordinating action steps to address the weed.

The MDA is investigating how the weed may have been introduced to the state.

In August, an Extension blog updated steps for both prevention and management at z.umn.edu/palamthbknd.

Further information is available at z.umn.edu/MDAPalmerAmaranth.

MDA Weed of the Month is Yellow Starthistle

January’s Weed of the Month, yellow starthistle (Centurea solstitialis), is a toxic plant that infests millions of acres in the western United States. It is native to Eurasia and was likely brought to North America as a contaminant in alfalfa. Though widespread throughout the western states, there are no known populations in Minnesota.

Yellow starthistle has many characteristics that favor its invasiveness. The plant is an aggressive colonizer of pastures, grasslands, ditches, and disturbed areas. It produces abundant seed for reproduction and the seed remains viable for 10 years. The seed spreads by wind, water, vehicles, wildlife, and by moving contaminated soil and hay. Yellow starthistle depletes soil moisture and decreases species diversity. It is also highly toxic to horses, causing a fatal nervous disorder called “chewing disease”.

This noxious weed on the eradicate list has distinctive identification characteristics. It has yellow flowers with sharp spines at the base of the flower. The spines can injure eyes, noses, and mouths of livestock. An annual plant, it forms a rosette in the fall with lobed leaves. When it sends up the flowering stem in the spring and summer, the branches and stems are rigid and spreading. The stems and leaves are covered in white hairs that give it a grayish color.

Yellow Starthistle

Yellow starthistle flowers have sharp spines that can injure grazing animals. (Photo contributed from the Minnesota Department of Ag)Invi

Residents of Minnesota are asked to be on the lookout for yellow starthistle and to report sightings to the Minnesota Department of Agriculture. Management strategies are aimed at preventing seed formation and spread, and include the following:

  • Buy certified seed to plant hayfields and pastures.
  • Clean equipment, boots, clothes, after being in an infested area.
  • Prescribed burning can be used to effectively manage yellow starthistle.
  • In addition to prevention and cultural management, herbicides can also be used. For specific herbicide recommendations, please contact you regional University of Minnesota Extension Educator.

As a noxious weed on the eradicate list, all above and below ground parts of the plant must be destroyed. To report infestations of yellow starthistle or any other noxious weeds on the eradicate list, please contact Arrest the Pest by voicemail at 888-545-6684 or email at arrest.the.pest@state.mn.us.