Ryan Miller, Extension crops educator, and Tony Cortilet, Minnesota Department of Agriculture
Palmer amaranth was added to the Minnesota Noxious Weed List in 2015; plants that earn a place on the noxious weed list have the potential to be or are known to be detrimental to some aspect of the common good. The full details on Minnesota’s noxious weed law can be found here.
Plants making it on the noxious weed list are placed in one of five categories: prohibited-eradicate, prohibited-control, restricted noxious, specially regulated plants, or county noxious weeds. Palmer amaranth was placed in the prohibited-eradiate category. This category contains weeds not known to exist in Minnesota or weeds not widely distributed in the state, and weeds in this category must be eradicated.
In 2016, there was a significant introduction of Palmer amaranth to Minnesota; this came with a conservation seed blend that had sourced some of the seed from farms in Texas and Kansas. Palmer amaranth, a plant native to the desert southwest, was well suited to grow in areas like Texas and Kansas and had been a longtime weed of these areas. Palmer amaranth was proactively put on the MN noxious weed list in 2015 because Palmer is a weed that grows faster than waterhemp and is more competitive and potentially more destructive to crop yields. It also has issues with herbicide resistance further complicating its control and management. Farmers and ag professionals to our south would refer to Palmer as “waterhemp on steroids”, a problem we certainly don’t need. After the introduction in 2016, Minnesota Department of Agriculture (MDA) set up a monitoring and eradication program with help from farmers, crop consultants, and University of Minnesota Extension.
Since 2016, 121 sites have been reported in Minnesota and at only 44 of these sites Palmer amaranth has been able to establish populations. Extensive surveillance and eradication efforts have largely been successful with only 7 sites in 7 counties still being monitored. Palmer amaranth is considered eradicated at a site after three years with no observed Palmer amaranth populations. In 2025, there are 4 new sites being investigated. If you suspect a new Palmer infestation, please take time to report it through the report a pest website.
The contaminated seed pathway of introduction is certainly important, but significant work has been done to reduce this risk. It is important to purchase seed from reputable seed suppliers in Minnesota and if possible, it would be best to source seed grown in Minnesota where Palmer amaranth is not a major issue.
There are several other pathways of introduction that should be kept in mind when trying to keep an eye out for new infestations. Farm machinery could be a source, particularly harvest equipment that has been used in states known to harbor palmer amaranth populations. Machinery should be thoroughly cleaned before using in Minnesota. Importing hay and other livestock feed from areas known to have Palmer amaranth infestations are another important potential source. Contaminated feed sources that are fed to livestock generate manure, manure that will contain Palmer seeds creating a new source. If you determine a feed source was likely contaminated with Palmer it will be important to monitor fields where you spread the manure and proactively manage any infestations. Sunflower and millet screenings have been two important culprits in this pathway of introduction.
One last thing, Palmer amaranth is a pigweed and can be difficult to distinguish from other common pigweeds (e.g. waterhemp). Here is a good resource to help you identify Palmer amaranth.
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| Palmer amaranth found in Yellow Medicine County in 2016. |
Plants making it on the noxious weed list are placed in one of five categories: prohibited-eradicate, prohibited-control, restricted noxious, specially regulated plants, or county noxious weeds. Palmer amaranth was placed in the prohibited-eradiate category. This category contains weeds not known to exist in Minnesota or weeds not widely distributed in the state, and weeds in this category must be eradicated.
In 2016, there was a significant introduction of Palmer amaranth to Minnesota; this came with a conservation seed blend that had sourced some of the seed from farms in Texas and Kansas. Palmer amaranth, a plant native to the desert southwest, was well suited to grow in areas like Texas and Kansas and had been a longtime weed of these areas. Palmer amaranth was proactively put on the MN noxious weed list in 2015 because Palmer is a weed that grows faster than waterhemp and is more competitive and potentially more destructive to crop yields. It also has issues with herbicide resistance further complicating its control and management. Farmers and ag professionals to our south would refer to Palmer as “waterhemp on steroids”, a problem we certainly don’t need. After the introduction in 2016, Minnesota Department of Agriculture (MDA) set up a monitoring and eradication program with help from farmers, crop consultants, and University of Minnesota Extension.
Since 2016, 121 sites have been reported in Minnesota and at only 44 of these sites Palmer amaranth has been able to establish populations. Extensive surveillance and eradication efforts have largely been successful with only 7 sites in 7 counties still being monitored. Palmer amaranth is considered eradicated at a site after three years with no observed Palmer amaranth populations. In 2025, there are 4 new sites being investigated. If you suspect a new Palmer infestation, please take time to report it through the report a pest website.
The contaminated seed pathway of introduction is certainly important, but significant work has been done to reduce this risk. It is important to purchase seed from reputable seed suppliers in Minnesota and if possible, it would be best to source seed grown in Minnesota where Palmer amaranth is not a major issue.
There are several other pathways of introduction that should be kept in mind when trying to keep an eye out for new infestations. Farm machinery could be a source, particularly harvest equipment that has been used in states known to harbor palmer amaranth populations. Machinery should be thoroughly cleaned before using in Minnesota. Importing hay and other livestock feed from areas known to have Palmer amaranth infestations are another important potential source. Contaminated feed sources that are fed to livestock generate manure, manure that will contain Palmer seeds creating a new source. If you determine a feed source was likely contaminated with Palmer it will be important to monitor fields where you spread the manure and proactively manage any infestations. Sunflower and millet screenings have been two important culprits in this pathway of introduction.
One last thing, Palmer amaranth is a pigweed and can be difficult to distinguish from other common pigweeds (e.g. waterhemp). Here is a good resource to help you identify Palmer amaranth.
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