The weed team at the Minnesota Department of Agriculture has chosen Palmer amaranth as its "Weed of the Month" for November.

The weed team works with local governments and landowners to protect state lands and citizens from injurious impacts of noxious and invasive weeds. The team regularly choses weeds to highlight and offers basic information and photos of them on the agency website, mda.state.mn.us/plants/pestmanagement/weedcontrol.aspx.

DOWN WITH PALMER: State weed scientists ask farmers and landowners to report if they find Palmer amaranth on their property, so efforts can be focused on eradicating it before the weed gets out of control.

Amaranthus palmeri is a fast-growing weed that has developed resistance to multiple herbicide modes of action, so it is difficult to control. MDA and University of Minnesota Extension scientists first identified and confirmed Palmer’s presence in the state in September. The initial plant was found in a native seed planting plot on a farm in eastern Yellow Medicine County.

Palmer amaranth produces a lot of seed — up to 250,000 per plant — and is highly competitive, according to MDA. It spreads quickly and can cause extensive crop losses, including in corn and soybean production.

Palmer amaranth is native to the arid southwestern United States and northwestern Mexico. It was accidentally introduced to the southeastern U.S. and became the most troublesome weed in cotton production. It developed resistance to many herbicides' modes of action and spread to row-crop fields in much of the eastern half of the country.

Palmer amaranth can be distinguished from the closely related waterhemp and other pigweeds by its long petiole length, and very tall flower and seed spikes. Unlike other pigweeds, Palmer amaranth petioles are often longer than the leaf blades. A petiole attaches a leaf to a stem. The flowering spike is much longer than that of other pigweeds. Leaves of some Palmer amaranth plants have a whitish V-shaped mark on them. Palmer amaranth is a summer annual that commonly reaches heights of 6 to 8 feet, but can reach 10 feet.

MDA and U-M scientists encourage farmers to scout for this weed and if found, to report it immediately. The quicker that farmers and ag consultants identify and manage Palmer, the better the state’s chances to minimize the impact to Minnesota’s ag industry.

Call the Arrest the Pest hotline at 888-545-6684 or email [email protected].

Source: MDA