Jeff Gunsolus, Extension Agronomist-Weed Science

This fall, Palmer amaranth was discovered for the first time in soybean fields in Redwood and Jackson counties. In Redwood County, 1 female and 3 male plants were found and in Jackson County, 1 female plant was found. All plants were destroyed, no seed was discovered and no additional plants were found within a 5 mile radius. The seed source is under investigation but likely routes would include contaminated field equipment and water and manure transport. North Dakota is experiencing a similar situation.

Past detections in 2016 and 2017
Our first detections of Palmer amaranth in Minnesota occurred in 2016 in CRP plantings in Yellow Medicine and Lyon Counties. Contaminated CRP seed was also responsible for Palmer amaranth detection in Todd and Douglas counties in 2017. At this time six other counties in Minnesota were found to be planted with CRP contaminated seed lots but no plants have been found in the field.

To date, the reporting triangle of farmer and crop consultant – U of MN Extension – Minnesota Department of Agriculture (MDA) has been responsible for maintaining the Palmer amaranth infestation to very low levels. Early detection prevents the potential for seed spread via combines and other field equipment and allows the MDA time to investigate the potential source, stop recurrence (if possible) and to assess the infested site.

Reporting to the MDA will not identify a farm field location but if Palmer amaranth is confirmed then the county where the infestation occurred will be reported.

Identification characteristics of Palmer amaranth
Palmer amaranth is challenging to identify as many of the amaranth species look similar. However, at this time of the year identification is easier when the plants are in their reproductive phase of development. For help in identification please go to the following web link http://z.umn.edu/palmerid

Key characteristics to look for would include: rapid growth that can reach over 6 feet in unmown areas, plant is smooth with no hairs on stems or leaves, leaf petiole (the stalk connecting the leaf to the stem) is often longer than the leaf and seed and pollen heads can reach 1 to 3 feet in length. However, the most consistent characteristic is the spiny bracts found on the female seed head (see Photo courtesy of Bruce Potter).

To help you separate Palmer amaranth from the other amaranth species commonly found in Minnesota please go to the web link posted above and reference “Amaranth identification and biotypes” under the “Additional guidance” section.

Reporting process
Please understand that you will not be in trouble for having Palmer amaranth in your field and due to the multiple routes of entry it is not a direct reflection on your farming practices. Also, the MDA and U of M will protect this information to our greatest ability.

If you or your crop consultant suspect the presence of Palmer amaranth the MDA and U of MN Extension suggest the following reporting process:

1) Take pictures of the plant(s) in question – pictures should include clear visibility of the whole plant, a close-up of the leaf and where it attaches to the stem, the flower head, and a leaf with the petiole folded over.

2) Contact U of MN Agronomy Extension, or MDA immediately and provide the pictures. Please include a phone number where you can be reached.

3) It would be preferred to leave the plants in the field until MDA or U of M can get to the location and verify the plant and collect genetic material for confirmation. Some Palmer is fairly straight-forward to identify from pictures, others need genetic confirmation. It is important at this stage of Palmer invasion in MN not to be destroying plants on your own without confirmation or notifying the MDA.  If plants have already been hand pulled, collect at least five leaf samples from each plant, place in a Ziploc bag, and refrigerate

Key contacts for reporting Palmer amaranth
The crop consultant – farmer connection has, to date, been a vital link to reporting to MDA and U of MN Extension and for that we want to thank you.

Key reporting contacts are as follows:

Arrest the Pest – Web: http://www.mda.state.mn.us/plants-insects/arrest-pest Email: arrest.the.pest@state.mn.us (visit website for information to include) Phone 1-888-545-6684

Denise Theide – Densie.Theide@state.mn.us ; 651-201-6531

Anthony Cortilet – Anthony.Cortilet@state.mn.us ; 651-201-6538

Shane Blair – Shane.Blair@state.mn.us ; 507-884-2116

U of M Extension – Jeff Gunsolus – gunso001@umn.edu

U of M Extension Agronomy Educators:  https://extension.umn.edu/crop-production/contacts-crop-production

 

Source: University of Minnesota Extension: Minnesota Crop News