Hit Them When They're Down

Not the most sporting tactic, but when dealing with Japanese knotweed (Fallopia japonica), certainly the right thing to do.

Japanese knotweed completely blocks light from getting to the ground layer, so that nothing but it lives under its canopy. In the fall those canes die back exposing open ground. The dead canes of Fallopia protect its rhizomes from the worst of winter frost and freezing. By carefully removing and burning the old stalks and leaving the ground open, you will let mother nature work on these invaders who come from a client that is not as extreme as Wisconsin. If possible, burn the canes onsite to eliminate the possibility of spreading the infestation.

While winter will not kill Japanese knotweed, it will weaken the plant making herbicide treatment in the spring more effective.

Coming to a Radside Near You

Japanese knotweed (Fallopia japonica) is listed by the World Conservation Union as on of the World's 100 Worst Invasive Species. The roots of Japanese knotweed, also known as Mexican bamboo, can break up blacktop roads and concrete foundations. Many banks in Scotland refuse to write mortgages for property whose soil is infested this invader.

The plant spreads through both sexual reproduction and vegetatively through rhizomes. The plant sends dies back to the ground every fall and sends up new stalks that reach more than 10 feet tall. A small piece of root falling off the back of a dump truck is enough to spark a new clone. Once established, a clone can spread ten meters a year. Its roots reach 20-25 feet deep. Attempting to remove Fallopia japonica by digging it up is extremely dangerous, as each little piece of the massive root system has the potential to start a new clone. The most effective means of control is herbicide applied injected into hollow stalks or as a foliar spray, several times a year, over multiple years.

The image above was recently taken along a county highway just south of Spring Green. This stand is particularly dangerous because it includes seed producing female plants. The fact that it has seed means that there is also a male plant nearby to pollinate it.

The Southwestern Wisconsin Weed Management Association (SWWMA) is a coalition of private landowners, public land managers, highway departments, consultants and contractors, as well as conservation groups dedicated to controlling the spread of invasive plants and preventing new speices from getting established. Our service area includes Grant, Lafayette, Iowa, Dane, Crawford, Richland and Sauk counties in Wisconsin.

SWWMA Affiliates with IPAW

The Invasive Plants Association of Wisconsin (IPAW) board of directors agreed at their September 27, 2010 meeting to approve the fiscal agency agreement with the Southwestern Wisconsin Weed Management Assoication (SWWMA). This agreement means that IPAW will serve as the umbrella organization for SWWMA, allowing it to qualify for tax-exempt donations and grants.

According to SWWMA president Mark Horn, "We are delighted to be associated with IPAW. They have an outstanding reputation and make a broad range of resources available to our growing organization."

SWWMA is a cooperative weed management association covering Grant, Lafayette, Iowa, Dane, Crawford, Richland and Sauk counties in southwestern Wisconsin.