The Minnesota Department of Agriculture (MDA), as the regulatory agency for managing noxious weeds, helps local governments with weed management and enforcement of the Minnesota Noxious Weed Law. A noxious weed is defined by the Minnesota Noxious Weed Law as an annual, biennial, or perennial plant that the Commissioner of Agriculture designates to be injurious to public health, the environment, public roads, crops, livestock, or other property.
State regulated noxious weeds are defined by three categories: Prohibited Noxious Weeds, Restricted Noxious Weeds and Specially Regulated Plants. Prohibited Noxious Weeds are placed on one of two regulatory lists; Prohibited Eradicate or Prohibited Control. Prohibited Eradicate species must have all above and below ground parts of the plant destroyed. Prohibited Control plants must be prevented from spreading propagating parts. Restricted Noxious Weeds are widely distributed in Minnesota and the importation, sale and transportation of their propagating parts are prohibited. Specially Regulated Plants have the potential to cause harm and have specific management plans or rules that define the use and management for the plants.
Listed species go through a rigorous evaluation to determine their invasiveness, difficulty and cost of control, benefit, and injury or harm it may cause to humans, livestock and the environment. Each species is reevaluated every three years, and with the exception of emergency listed species, the Noxious Weed List only changes every three years.
In 2018, the MDA made two changes to Noxious Weed List. The first is the emergency listing of poison hemlock (Conium maculatum) to the Prohibited Eradicate List. Poison hemlock went through extensive evaluation in 2017 and due to its high toxicity and distribution throughout the state was listed immediately in 2018.
The second change to the Noxious Weed List was the movement of 25 Japanese barberry cultivars to the Restricted List. These 25 cultivars were placed on the Specially Regulated list in 2015 as a three year production phase-out. On January 1, 2018, these cultivars became Restricted Noxious Weeds in Minnesota and are illegal to sell and propagate.