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Weed of the Month: Oriental bittersweet

November 30, 2018 GMT

WINONA — In southeast Minnesota, an invasive woody vine has caused property damage and altered ecosystems with its prolific seed production and aggressive growth.

Oriental bittersweet was first confirmed in the Twin Cities in 2010, and has since been confirmed in multiple counties with the most severe infestations in Red Wing and Winona.

After the species was listed on the Minnesota noxious weed list in the prohibited-eradicate category in 2011, efforts were first concentrated on mapping and developing management strategies to contain the spread. In 2013, the Minnesota Department of Agriculture obtained funding from the Environment and Natural Resources Trust Fund to start an eradication program.

In Winona, local efforts to control infestations of oriental bittersweet have been led by the county.

Anne Morse, the county’s Sustainability Coordinator and Assistant County Agricultural Inspector, has organized workshops hosted on neighborhood residents’ property in which participants learn how to identify and manage oriental bittersweet. Working neighborhood by neighborhood, Morse is empowering people to better manage invasive plants on their land.


Building community involvement is essential for long-term success. Morse was already connected with many community leaders and was able to recruit volunteers by pitching the project to teachers, outdoor recreation groups, civic groups, and networks of personal friends. Through these recruitment strategies, Morse assembled a group of committed individuals “who cherish and are passionate about recreating our blufflands.”

To engage landowners, Morse found a successful strategy by holding open houses in individual neighborhoods, which in Winona are wooded valleys within the extensive Mississippi river bluff landscape. Invitations were sent via mail to all landowners in each valley for “Root Beer and Bittersweet” events, which were held at the end of a workday. At the open houses, attendees learned about the eradication effort, were given a tour of nearby infested areas, and encouraged to sign up for an evaluation of their property.

Coordinated efforts between state and local partners has increased efficiency and maximized outcomes for bittersweet management. Morse said Winona County is “assiduous in documenting contacts and all property data of every landowner we speak with.” Winona County has “also invested in mapping the intensity of infestations on all the properties we have evaluated.”

She also focuses on the volunteers and landowners, working “to make volunteer experiences as gratifying as possible, being sure to plan for needs, and being responsive.” The Winona Invasive Species Working Group has been meeting for several years to build connections, share knowledge and strategize to continue to eradicate oriental bittersweet.