Japanese Knotweed—A Growing Problem
A Japanese Knotweed infestation in Sandy Hook, CT
This article originally appeared in the Newtown Bee on August 25, 2023 - Protect Our Pollinators (POP) column: My Backyard Habitat.
It looks like bamboo and towers about six feet high this time of year. You’ve driven past it growing in thick clumps along Mount Pleasant Road, Mile Hill, Johnny Appleseed Lane, and many other roads in town. It thrives along riverbanks as one can see on the Pootatuck River in Sandy Hook Center. It is Japanese knotweed, a tenacious plant that evolved to survive on active volcanoes in Japan and is now spreading unchecked in Newtown and the U.S. It is reported to be present and spreading in 42 states from coast to coast and eight Canadian provinces.
This plant, native to Japan, China and Korea, forms large, nearly pure monocultures with 4-12 feet tall, round bamboo-like canes. Its underground rhizomes can travel 23 feet from the parent plant and penetrate seven feet downward. As this plant is cut along roadsides for visibility purposes, the stem fragments left behind or carried to a new spot by the mower can sprout into new plants and form new stands.
Japanese knotweed plants are so tenacious that they can penetrate pavement, foundations and septic tanks. Its dense stands push out other vegetation that we need and native wildlife need. It spreads and spreads. Yet it isn’t visible year-round. Unsuspecting home buyers may get a rude surprise in the spring when they find they have an infestation.
In the United Kingdom knotweed is described as “notoriously rampant” and “the most pernicious weed in Britain” and it can drive down property values there by as much as 10 percent. Consequently, UK property with knotweed infestations must be disclosed by owners before selling. This legal enforcement protects prospective buyers. In the U.S. there is currently no legal recourse in place for buyers of infested property.
The good news is that it can be controlled, and other towns such as Woodbury and Stamford have begun acknowledging the issue and working on reversing the trend of knotweed proliferation. In Newtown, it would be helpful for town officials to know the extent of the problem and to know exactly where those problem areas are. A website (www.newtownknotweed.org) has been set up which contains a map of some of the areas. If you find a knotweed infestation please help this mapping process by scouting your property and surrounding areas for it, paying close attention to the roadside, riverbanks, wetlands and partially shaded areas. Once you find such areas, please take photographs with a cell phone, note your location and send it to newtownknotweed@gmail.com to get it on the map.
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It looks like bamboo and towers about six feet high this time of year. You’ve driven past it growing in thick clumps along Mount Pleasant Road, Mile Hill, Johnny Appleseed Lane, and many other roads in town. It thrives along riverbanks as one can see on the Pootatuck River in Sandy Hook Center. It is Japanese knotweed, a tenacious plant that evolved to survive on active volcanoes in Japan and is now spreading unchecked in Newtown and the U.S. It is reported to be present and spreading in 42 states from coast to coast and eight Canadian provinces.
This plant, native to Japan, China and Korea, forms large, nearly pure monocultures with 4-12 feet tall, round bamboo-like canes. Its underground rhizomes can travel 23 feet from the parent plant and penetrate seven feet downward. As this plant is cut along roadsides for visibility purposes, the stem fragments left behind or carried to a new spot by the mower can sprout into new plants and form new stands.
Japanese knotweed plants are so tenacious that they can penetrate pavement, foundations and septic tanks. Its dense stands push out other vegetation that we need and native wildlife need. It spreads and spreads. Yet it isn’t visible year-round. Unsuspecting home buyers may get a rude surprise in the spring when they find they have an infestation.
In the United Kingdom knotweed is described as “notoriously rampant” and “the most pernicious weed in Britain” and it can drive down property values there by as much as 10 percent. Consequently, UK property with knotweed infestations must be disclosed by owners before selling. This legal enforcement protects prospective buyers. In the U.S. there is currently no legal recourse in place for buyers of infested property.
The good news is that it can be controlled, and other towns such as Woodbury and Stamford have begun acknowledging the issue and working on reversing the trend of knotweed proliferation. In Newtown, it would be helpful for town officials to know the extent of the problem and to know exactly where those problem areas are. A website (www.newtownknotweed.org) has been set up which contains a map of some of the areas. If you find a knotweed infestation please help this mapping process by scouting your property and surrounding areas for it, paying close attention to the roadside, riverbanks, wetlands and partially shaded areas. Once you find such areas, please take photographs with a cell phone, note your location and send it to newtownknotweed@gmail.com to get it on the map.
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