A community coalition to rid Newtown, Connecticut of the invasive weed that blocks visibility along our roadsides, takes over streambanks, and pushes out native plants.
Japanese knotweed thrives in disturbed areas, like roadsides, as well as stream and riverbanks. You may have already seen it, not realizing what it was. Due to its extensive underground root system, Japanese knotweed quickly dominates an area, out-competing other plants while withstanding shade, drought and high temperatures.
Knotweed suppresses the growth of neighboring plants, alters soil chemistry, contributes to erosion and floods, and jeopardizes streambank stability. It reduces the number of aquatic macroinvertebrates, which are an integral part of the aquatic food chain.
Property damage caused by Japanese knotweed includes infiltration of structures with weak foundations. Its roots can grow through pavement, bricks or stonework, or creep into masonry cracks.
Japanese knotweed is widespread in Newtown and can be found on our roadsides, at Dickinson Park, Fairfield Hills, along the banks of the Pootatuck River, and in other cherished places. Check out the map below to see if knotweed has been found in your neighborhood; you can help us compile a more thorough inventory of knotweed by reporting your sightings below.
Let’s work together to reduce the spread of knotweed on town land and on our own properties.
Knotweed suppresses the growth of neighboring plants, alters soil chemistry, contributes to erosion and floods, and jeopardizes streambank stability. It reduces the number of aquatic macroinvertebrates, which are an integral part of the aquatic food chain.
Property damage caused by Japanese knotweed includes infiltration of structures with weak foundations. Its roots can grow through pavement, bricks or stonework, or creep into masonry cracks.
Japanese knotweed is widespread in Newtown and can be found on our roadsides, at Dickinson Park, Fairfield Hills, along the banks of the Pootatuck River, and in other cherished places. Check out the map below to see if knotweed has been found in your neighborhood; you can help us compile a more thorough inventory of knotweed by reporting your sightings below.
Let’s work together to reduce the spread of knotweed on town land and on our own properties.
Read: Knotweed Treatment Recommendations for Homeowners and Landscapers
Where is knotweed currently found in Newtown?
Japanese Knotweed Fact Sheet
Japanese knotweed is one of the most damaging invasive species in North America. Trouble is, a lot of misinformation is dispensed for knotweed management on many websites and from inexperienced landscapers who can make a bad infestation even worse.
The best available science shows that mowing, cutting, digging and/or tarping is not effective in controlling knotweed and can even stimulate root growth. The consensus among experts who work with knotweed is that the only effective control method is application of an herbicide weedkiller at a very specific time – late summer, after flowering but before a killing frost.
We cannot underestimate Japanese knotweed. Japanese knotweed is considered one of the most resilient organisms on Earth, even surviving hot lava flows in its country of origin. The roots or rhizomes can grow more than 10 feet deep and travel laterally 35 feet beyond the woody stems. And, knotweed can remain dormant for more than 20 years, just biding its time for an opportunity to resprout.
What do you do if you have Japanese knotweed?
The first thing to do is identify the plant as knotweed. Look at the photos on this site and go to this website for help: https://www.phlorum.com/japanese-knotweed/identification/www.phlorum.com/japanese-knotweed/identification/
Do not cut, mow, or dig it. Physical methods such as mowing or cutting stems, digging plants out and/or tarping just don’t work with knotweed. Disturbance often promotes extremely aggressive lateral rhizome (root) growth.
Do not spread it. When knotweed is cut, mowed or dug, tiny pieces of root or stem can be tracked to new locations that create new stands of knotweed.
There are several ways that knotweed can spread:
1. Taking dug or cut stems and roots to a town landfill or dumping in a natural area.
2. Mowing and/or brush cutting that drags or blows knotweed beyond the existing area of
infestation.
3. Transporting by machines when pieces are stuck or lodged in mower decks and wheels.
4. Moving soil that has not been sifted and contains bits of knotweed. Remember, even small
roots or stems can regenerate in a new area.
5. Sharing or selling plants from your yard when pieces of knotweed are in the soil.
Do use an herbicide treatment. It should be noted that glyphosate controls knotweed but does not eradicate it. Management of Japanese knotweed is a multi-year process. And, as mentioned above, it must be done at the right time of year. It should also be noted that spraying herbicide comes with a risk to watercourses. Wetland restrictions may apply. Therefore, it is the recommendation of the Newtown Knotweed Initiative that a licensed pesticide applicator, educated in this plant’s phenology and with experience in management of Japanese knotweed, be consulted.
How environmentally damaging is Japanese knotweed?
Japanese knotweed is an invader of natural areas, displacing our native flora. When native plants are eliminated, populations of beneficial insects, birds, and other wildlife will follow.
According to reports in the United Kingdom, knotweed is causing property values to decline. It is also making it harder for first-time buyers to get mortgages on properties invaded with knotweed. UK courts have even started to award damages for properties encroached upon by knotweed.
To protect our properties and wild places, we need to take Japanese knotweed seriously and do everything we can to prevent further spread. It is important to refrain from mowing, cutting, digging and especially transporting to new areas.
The best available science shows that mowing, cutting, digging and/or tarping is not effective in controlling knotweed and can even stimulate root growth. The consensus among experts who work with knotweed is that the only effective control method is application of an herbicide weedkiller at a very specific time – late summer, after flowering but before a killing frost.
We cannot underestimate Japanese knotweed. Japanese knotweed is considered one of the most resilient organisms on Earth, even surviving hot lava flows in its country of origin. The roots or rhizomes can grow more than 10 feet deep and travel laterally 35 feet beyond the woody stems. And, knotweed can remain dormant for more than 20 years, just biding its time for an opportunity to resprout.
What do you do if you have Japanese knotweed?
The first thing to do is identify the plant as knotweed. Look at the photos on this site and go to this website for help: https://www.phlorum.com/japanese-knotweed/identification/www.phlorum.com/japanese-knotweed/identification/
Do not cut, mow, or dig it. Physical methods such as mowing or cutting stems, digging plants out and/or tarping just don’t work with knotweed. Disturbance often promotes extremely aggressive lateral rhizome (root) growth.
Do not spread it. When knotweed is cut, mowed or dug, tiny pieces of root or stem can be tracked to new locations that create new stands of knotweed.
There are several ways that knotweed can spread:
1. Taking dug or cut stems and roots to a town landfill or dumping in a natural area.
2. Mowing and/or brush cutting that drags or blows knotweed beyond the existing area of
infestation.
3. Transporting by machines when pieces are stuck or lodged in mower decks and wheels.
4. Moving soil that has not been sifted and contains bits of knotweed. Remember, even small
roots or stems can regenerate in a new area.
5. Sharing or selling plants from your yard when pieces of knotweed are in the soil.
Do use an herbicide treatment. It should be noted that glyphosate controls knotweed but does not eradicate it. Management of Japanese knotweed is a multi-year process. And, as mentioned above, it must be done at the right time of year. It should also be noted that spraying herbicide comes with a risk to watercourses. Wetland restrictions may apply. Therefore, it is the recommendation of the Newtown Knotweed Initiative that a licensed pesticide applicator, educated in this plant’s phenology and with experience in management of Japanese knotweed, be consulted.
How environmentally damaging is Japanese knotweed?
Japanese knotweed is an invader of natural areas, displacing our native flora. When native plants are eliminated, populations of beneficial insects, birds, and other wildlife will follow.
According to reports in the United Kingdom, knotweed is causing property values to decline. It is also making it harder for first-time buyers to get mortgages on properties invaded with knotweed. UK courts have even started to award damages for properties encroached upon by knotweed.
To protect our properties and wild places, we need to take Japanese knotweed seriously and do everything we can to prevent further spread. It is important to refrain from mowing, cutting, digging and especially transporting to new areas.
To learn more…
Join the Worldwide Japanese Knotweed Support Group Facebook group.
Read this 2018 scientific journal article, which documented that only glyphosate effectively controls Japanese knotweed
Read a detailed Guardian article on Japanese knotweed
Read this article on the most sustainable method of dealing with Japanese knotweed
Join the Worldwide Japanese Knotweed Support Group Facebook group.
Read this 2018 scientific journal article, which documented that only glyphosate effectively controls Japanese knotweed
Read a detailed Guardian article on Japanese knotweed
Read this article on the most sustainable method of dealing with Japanese knotweed
| Download the Fact Sheet |
