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February 2, 2024

February Weed of the Month: 2023 New County Finds of Prohibited Eradicate List Noxious Weeds

The highest priority weeds are in the Prohibited Eradicate category

Emilie Justen, Minnesota Department of Agriculture

The Minnesota Department of Agriculture (MDA) — with assistance from county agricultural inspectors, township supervisors, and city mayors — helps protect residents of the state from the negative effects of noxious weeds. A noxious weed is an annual, biennial, or perennial plant that damages public health, the environment, public roads, crops, livestock, or other property. Noxious weeds are regulated by the Minnesota Noxious Weed Law.

Noxious weeds are designated into four categories: Prohibited Eradicate, Prohibited Control, Restricted, and Specially Regulated. The highest priority weeds are in the Prohibited Eradicate category. To prevent these species from becoming widespread throughout the state, the law requires species in this category to have all above and below ground plant parts destroyed.

Collaboration with multiple agencies and organizations throughout the state helps the MDA successfully detect noxious weeds in the Prohibited Eradicate category and confirm unrecognized species. In 2023, two Prohibited Eradicate species were confirmed for the first time in two counties:

Left: A Palmer amaranth seedhead in a native planting. The seedhead is about 2 feet long and 1 inch wide.

Right: Red hailstone is a vine with tendrils and bright yellow flowers.

Click here to download the photo.

Palmer amaranth is a high-profile noxious weed of row crops. Red hailstone is an herbaceous perennial vine with heart-shaped leaves, tendrils, and showy yellow flowers; the vines have underground tubers that make it a challenge to manage.

The number of new county finds of Prohibited Eradicate noxious weeds has decreased since 2019. Several species (meadow knapweed, poison hemlock, and round leaf bittersweet) were moved from the Prohibited Eradicate category to the Prohibited Control category in 2023; in prior years, those species were found in new counties multiple times. After years of surveying and mapping these species, they were too widespread to be considered for the Prohibited Eradicate category.

The MDA verifies reports and collects voucher samples of Prohibited Eradicate noxious weeds when possible for the official University of Minnesota herbarium records. The MDA also helps local governments with weed management and enforcement of the Minnesota Noxious Weed Law. The MDA provides training to the county agriculture inspectors (CAIs) while the CAIs enforce the Minnesota Noxious Weed Law.

MEDIA: For more information on Weed of the Month, contact Brittany Raveill, MDA Communications, at brittany.raveill@state.mn.us or 651-201-6131