Invasive Plant Species Control
Invasive plants can disrupt natural areas like meadows, wetlands, and forests. They also negatively impact agriculture economies and can be harmful to our health. A few Minnesota-specific websites with information about invasive plants, including how to identify and report, are linked below:
St. Louis County Public Works 2025 Invasive Plant Control plan:
- St. Louis County has received a Noxious Weed Control Grant from the Minnesota Department of Agriculture to help cover the cost of having a contractor treat wild parsnip and knotweed in 2025. We have contracted with Prairie Restorations Inc., to selectively spray herbicide in the county road right-of-way and at select private properties with owner permission. Spraying will occur in June to kill wild parsnip and in August – September to kill invasive knotweed.
- The County must receive a signed landowner Permit of Entry (PoE) form before treatment can occur on private property. Return completed PoE forms (Permit of Entry Form Link) by email to andrewsc@stlouiscountymn.gov or mail to Carol Andrews, 4787 Midway Rd, Duluth MN 55811. If you have requested assistance treating knotweed please return a PoE form as soon as possible.
- Approximately 2 to 4 weeks before treatment occurs the County will send postcards to property owners on our 2025 knotweed treatment list and to owners of properties very near intended treatment locations.
- The following plants are targeted for treatment by SLC Public Works:
- Wild parsnip - Wild parsnip is highly invasive and, if ignored, can spread rapidly, developing into large monocultures that replace native communities. It reduces the quality of agricultural forage crops and can negatively impact livestock when ingested. The plant sap contains toxic chemicals that are activated by sunlight and can cause serious burns and blisters to human skin after contact. This makes it a threat to hikers, highway maintenance workers, ATV riders and anyone else who may use the ditches along roadways.
- Invasive knotweed (aka Japanese/Bohemian knotweed) - Invasive knotweed is an invasive exotic plant with hollow bamboo-like stems that can grow over 10’ high. In addition to negative environmental impacts this plant creates safety hazards by blocking site lines along driveways and road intersections. It can also negatively impact waterways, damage home foundations and pavement. The plant grows too quickly to control by routine roadside mowing. In addition, mowing can contribute to spreading the plant to new areas and lead to even more vigorous growth.
- If you believe that wild parsnip or invasive knotweed extends from the road right-of-way onto your property, please contact Carol Andrews at 218-625-3862 or andrewsc@stlouiscountymn.gov if you are interested in having the County contractor treat the entire infestation. If knotweed or wild parsnip are farther than 33 feet from the road center line, then they are likely on private property. Note that assistance treating on private property is dependent on funding and other limitations.
WHAT CAN YOU DO TO HELP: The public can help reduce the spread of all invasive plant species by cleaning dirt and vegetation off of mowers, off-road vehicles etc. before and after using them. Avoid driving through or mowing stands of wild parsnip that have gone to seed.
To see more information including known locations or to report a new location of wild parsnip or invasive knotweed, visit the link below. The County uses EDDMaps as part of our treatment planning process.