Process to Eradicate Japanese Knotweed Along SW Bike Path Continues


City of Madison Engineering Announces Management Plans to Continue Multi-Year Control Effort

Here the native Brown-eyed Susan (Rudbeckia) is able to find space on the edge of the knotweed clone.

Here,  in the storm water channel below the South West Bike Path, the native Brown-eyed Susan (Rudbeckia) is able to find space on the edge of the invasive, non-native knotweed clone (white flowers).  This is as the clone appeared in 2013.  Most of the clone was killed by a herbicide application in fall, 2014.  The native plants remain and have been given greater breathing room since removal of the knotweed.

The City of Madison Engineering Division has announced vegetation management plans for this fall that will follow-up on work done the earlier two years to contain, and eventually eradicate, infestations of Japanese knotweed from portions of the right-of-way bordering the South West Commuter Path.   This blog has covered the Japanese knotweed story in several previous posts, click here for an overview of the Japanese knotweed problem, or click here for an example of how it has spread along the SW Bike Path.

“A contractor will be applying herbicide to Japanese knotweed during the week of August 24, 2015. This is a follow-up herbicide treatment to the 2014 treatment, which has proven to be very effective. The two sites being treated are 1) between Virginia Terrace and Glenway Street and 2) on the southwest side of Odana and SW bike path intersection (knotweed areas are approximate on images below).  Signs will be posted to alert bike path users of this work”, said Carissa Wegner of the City of Madison Engineering Division in a notification.

Why Worry About Japanese knotweed?

Japanese knotweed flowers are attractive but the plant behaves badly.

Japanese knotweed flowers are attractive but the plant behaves badly.

Japanese knotweed (Fallopia japonica); also known previously as Polygonum cuspidatum, is a vigorous perennial plant that spreads through rhizomes and is adapted to growing along waterways and in poor, rubble-strewn soil.   The reddish, hollow stems, about the size of your wrist,  can grow up to 4″ per day and reach a height of 10 to 12 feet, or more.  The stems grow with such force that they can push up through asphalt and does not respect property boundaries.   An established clone can spread to cover many acres and will continue to do so unless contained.

Control Measures

There are a variety of mechanical, cultural, and chemical control methods that may be appropriate and effective, depending upon the size, location, and age of the clone.  Click here to see an excellent pamphlet from UW Extension on current control measures.    Prevention of spread through root fragments is, of course, the preferred method.  For a long-established and extensive clone like the one along the SW Bike Path, herbicide application is probably the most practical control strategy.

Location of the patches to be eradicated

Working with City Parks and volunteer bike path stewards who plant and maintain gardens along the path, City Engineering has identified two main infestations that will be worked on this fall.

Knotweed treatment area along the SW Bike Path between Glenway Street. and Virginia Terrace.

Knotweed treatment area along the SW Bike Path between Glenway Street. and Virginia Terrace.

Second treatment area south of the bike path west of Odana Road.

Second treatment area south of the bike path west of Odana Road.

Provided the herbicide application is effective, and to fill the gap left by the soon-to-be-gone Japanese knotweed, City Engineering and path volunteers this fall will sow seeds of pioneering and aggressive native plants that will be able to compete with any future knotweed infestations.

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About Steve Glass

The blogger is a restoration ecologist practicing and writing in the Midwestern United States.
This entry was posted in invasive plants, SW Bike Path and tagged , . Bookmark the permalink.

2 Responses to Process to Eradicate Japanese Knotweed Along SW Bike Path Continues

  1. Pingback: Madison Tackles Japanese Knotweed Along SW Bike Path | WingraSprings

  2. Pingback: Update on Madison’s Effort to Control Japanese Knotweed Along SW Bike Path | WingraSprings

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