The Board of Commissioners recently voted to match a $1,500 grant to treat Japanese Knotweed, a non-native invasive plant common throughout the region. Knotweed is highly invasive, spreading from even the smallest cutting or fragment and aggressively spreading, crowding out native species, said Highlands Biological Station (HBS) Executive Director Jim Costa.
Costa said there are several benefits to treating for knotweed as well as other invasives to help maintain both the beauty and ecological health of the Plateau and environs.
“The area, like the region more generally, is renowned for its native plant species diversity, including a great many lovely flowering shrubs and wildflowers,” he said. “Invasives can spread like wildfire because they have been introduced far from their native range where there are natural checks on their populations. We seek to nip problem species in the bud, if you will, to prevent them from becoming both an eyesore and doing ecological damage by crowding out native wildflowers and shrubs.”
HBS is part of the Highlands Coalition for Non-native Invasive Plant Management (CNIPM), the group pushing for the treatment of knotweed and other invasive species and includes the Town of Highlands. The Town joined the coalition in 2016 after Highlands Mayor Pat Taylor signed a proclamation.
“The Town supports the efforts to eradicate invasive plant species as our commitment to preserve this beautiful, unique mountain environment,” said Taylor. “The knotweed tends to takeover streams and lake areas that are so critical to maintaining a healthy watershed.”
Other members of CNIPM include Land Stewards (Laurel Garden Club), Highlands-Cashiers Land Trust (HCLT), Highlands Historical Society, Highlands Plateau Audubon, and Highlands Plateau Greenway. The Town is matching a grant made by the Laurel Garden Club.
HCLT Stewardship Coordinator Kyle Pursel said knotweed is known to completely take over areas it infests by forming dense thickets and effectively shading or pushing out most other plants. It is mostly clonal, meaning it does not need to produce seeds to reproduce. It largely spreads by sprouting new plants from small pieces broken off existing plants. Plants along roadways can have pieces carried by cars or equipment that are not properly inspected for plant pieces and cleaned, while those along streams can have pieces float downstream to infest new areas. It also thrives in the Plateau’s climate and landscape, which allows it to quickly establish in new sites and grow rapidly.
“If left unchecked, knotweed and other invasive plants will forever alter our landscape,” said Pursel. “We are now at an important juncture on the Plateau where infestations, while growing, are still capable of being managed without significant use of both financial and human resources. Dealing with the problem now will save money and effort in the long-term.”
Pursel added that due to knotweed’s ability to easily and quickly spread by small pieces and its deep root system, knotweed is best treated chemically.
“It is best to treat it twice a year, in late summer and again in early fall, and to treat each successive year until no new plants pop up the following late spring,” he said. “It can take three-plus years to fully eradicate an infestation, so you must be diligent. Our plan is to treat it twice annually until we no longer notice new sprouts in the treated areas.”
There is something else about knotweed that’s a bit unique, said Pursel.
“Japanese knotweed is actually edible if you get the new shoots (which look like red-speckled asparagus) in spring (April-early May),” he said. “It tastes very similar, and has similar uses to, rhubarb. Just be aware of your surroundings as you don’t want to pick any that has been sprayed, are growing around trash, etc. Older plants tend to be too tough to eat.”
At February’s Town Board meeting, Commissioner Brian Stiehler, who has a turf, ornamental and acquatic license issued by the state of NC, said triclopyr will be sprayed on the Japanese Knotweed.
“It’s a selective, aquatic, contact herbicide – an old chemistry that has been around for a long time that isn’t toxic to fish, wildlife or even other plants like rhododendrons. And it only affects what it touches,” he said.
Still, applicators have to be certified, so some of the money the town agreed to allocate will be used to certify an applicator from Tate Landscaping for “roadsides and rights-of-way,” which is where most of the Japanese Knotweed on the plateau exists.
“Applicators have to know how the chemical can react in different environments. On roadsides there is a lot of run off and that sort of thing that they have to be aware of,” said Stiehler.
CNIPM puts on two workshops annually for homeowners and landscaping professionals so they can learn to recognize and control invasive plants, as well as the benefits of using native plants.
CNIPM also holds volunteer days combating invasive hotspots in town; last fall volunteers cleared a large amount of privet in the woods at the Highlands Rec Park, said Costa.
Pictured at the top of the article is Japanese Knotweed. Photo courtesy of Highlands-Cashiers Land Trust.