09/23/2024
GOT KNOTWEED?
It’s that time of year when a beautiful, leafy shrub unfurls its delicate blooms as an attractive hedge throughout our area. That shrub is Knotw**d.
The unfortunate reality is that Japanese, Bohemian and Himalayan Knotw**d (Reynoutria japonica, etc.) are aggressive, invasive species that will quickly take over any area where they’re allowed to spread unchecked, and can even threaten the integrity of foundations and sidewalks.
IS IT IN MY YARD?
See the photos below. The flowers are lacy and white, the stems like bamboo.
WHAT DAMAGE CAN IT DO?
Knotw**d can quickly choke out intentional plantings and native plants, and has an underground root system that can extend to 30-60' wide, and 6' deep.
If allowed to spread unchecked, it can grow into foundations and sidewalks. In England, if a property has knotw**d on it, the value of the home is decreased. According to Warren County Master Gardeners: “Due to the amount of damage knotw**d causes, if it's discovered at a property as a result of a normal mortgage valuation or property survey, many lenders will either refuse a mortgage altogether or impose specific criteria if they do decide to proceed at all. Under Environmental laws in England, failure to control the spread of the plant can result in civil nuisance claims which can mean legal action and heavy financial penalties. Knotw**d can also reduce the value of a property in England between £25,000 and £50,000 if knotw**d is formally identified by a surveyor. There is a growing concern in the United States.”
Yikes!!
And recent studies conclude that stream banks where knotw**d has choked out native plants experience greater erosion, increasing the negative impacts of floods.
HOW DOES IT SPREAD?
-The rhizomes, or roots, spread underground.
-Pieces of the stems left from casual w**ding, or stuck to machinery used to clear knotw**d from ditches and then used somewhere else without cleaning, can then deposit those pieces of stem in other areas where knotw**d can easily establish.
-Pieces of roots can be carried down stream and deposited to take root somewhere else.
-Pieces of knotw**d can get stuck in hooves or shoes, and drop off somewhere else where it takes root.
-Garden pruners or other tools that have been used on knotw**d and not properly cleaned with alcohol afterwards and then used in another part of the garden.
HOW DO I GET RID OF IT?
The best time to respond is as soon as you notice knotw**d in your yard or garden. The more established it gets, the harder it is to get rid of. Be prepared for several years of routine vigilance and response. There are many methods purported to successfully get rid of knotw**d - here’s a list you
can pick and choose from to use over the course of a few years. Each will have varying degrees of safety and effectiveness, but doing nothing will guarantee the knotw**d will overtake the area! Good Luck!
• Cut down the stalks in spring and fall. Put the stalks into a dark plastic bag and let sit in the sun for several days to desiccate. Then remove the dried stalks and burn completely. Wash all tools used thoroughly with alcohol.
• Pour vinegar or lemon juice into the cut stalks, 2-3 times over the growing season.
• Glyphosate, or 'Roundup', is dangerous to use, for humans, plants, and for the watershed as well. We are only presenting this since this method is often recommended, and one should be aware of its toxicity. Glyphosates are banned in many countries, and it is banned for use on state properties in New York. Additionally, it is not recommended for use near water (Such as the town of Westport, which slopes into Lake Champlain) or where it can leech into
ground water sources, nor should it ever be used when there is rain in the forecast. There are individual and class action lawsuits and millions of $ in
settlements paid to people with non-Hodgkins lymphoma as a result of using glyphosates.
**WE ARE NOT RECOMMENDING USING ROUNDUP OR OTHER BLENDS OF GLYPHOSATES**
For more detailed information on Glyphosates, visit
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9101768/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5606642/
https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/fee.1985
• Once you’ve cut back the knotw**d and treated the stalks, cover the entire area with a plastic tarp that prevents light from getting through, and leave in place for at least one year.
• If you have an especially large area that’s been invaded, a steep bank or a stand that covers multiple properties in close proximity to each other, hiring a professional who has experience is probably your best solution.
You can view stands of Knotw**d on Old Arsenal Road in Westport, and several other local areas!
Here's a good read on the invasives vs natives issue:
https://albopepper.com/natives-vs-non-natives-and-invasive-plants.php
