The Invasive Plant Council of NYS

Japanese Knotweed - Management

Please email ipcnys@tnc.org and describe management methods you recommend (or do not recommend). And thank you for taking time to share your experiences...

Steven Flint, with the Adirondack Park Invasive Plant Program (APIPP) is planning to use an injection tool this summer...(http://www.jkinjectiontools.com/)

Paul Fuhrmann, with Ecology and Environment, Inc., describes the Seneca Bluff project as an example of a successfully reclaimed Japanese Knotweed habitat: Thirty years of domination by Japanese Knotweed within the Buffalo River riparian corridor was ended by techniques applied during site clearing and grading. This involved rip (deep) tilling, repeated cultivation and fall planting of native forested floodplain species to modify habitat and out compete the remaining invasive seedbank. Community stewardship is critical to the success of this project involving hands-on maintenance, monitoring and adaptive management.

Cynthia Boettner with the Silvio O. Conte National Fish & Wildlife Refuge and the New England Invasive Plant Group, describes successful Japanese Knotweed control on a small island in the Connecticut River, "We have a small stand of knotweed that we cut three times per year for 4 to 5 years, taking great care not to cut the native plants in the area. The native plants increased in numbers and are now 'holding their own' against the knotweed. Currently only an annual cutting is necessary."

Chris Mattrick, with the New England Wild Flower Society and the Invasive Plant Atlas of New England, has been working on J.K. control for ten years. They have used various methods including repeated cutting, foliar applications of herbicide and stem injection. Chris feels that stem injection, although time-consuming, is the most effective treatment overall.

University of Washington

Monsanto Injection System Advertisement

For more information on Japanese Knotweed: "A Review of the Biology and Ecology of Three Invasive Perennials in New York State: Japanese Knotweed, Mugwort and Pale Swallow-wort" by Leslie A. Weston, Jacob N. Barney and Antonio DiTommaso.