Japanese Knotweed and Goatscaping

Japanese Knotweed – A Scourge for Our Lakesides and Waterways

by Jan Parsons, FOVLAP Board of Directors, from our Spring 2026 Newsletter. 

When Japanese knotweed (Fallopia japonica) was introduced into the United States in the late 1800s as an ornamental plant, it was appreciated as a herbaceous

perennial that could be used for erosion control and riverbank stabilization. It soon appeared in gardening catalogs in the 1890s and was found in New York, New Jersey and near Philadelphia. No one knew that by the year 2000, Japanese knotweed would be a growing invasive plant problem, aggressively invading natural habitats, outcompeting native plants and taking over waterfront areas throughout Vermont and other states.

In 2011, the floodwaters of Tropical Storm Irene tore through Vermont river valleys carrying knotweed fragments far downstream, causing a nuisance plant to become a “green monster.” The plant’s spread exploded along Vermont’s waterways, colonizing the newly disturbed, sediment-rich soils. Instead of helping stabilize riverbanks, it can take over and damage flood defense structures, undermining the water channels’ ability to manage floodwater. A 2021 study found that Japanese knotweed was associated with a significant increase in soil erosion. In addition, tall, dense stands of knotweed create a physical barrier preventing access to fishing, swimming and other recreational activities along miles of Vermont waterfront property.

In recent years, Vermonters have fought back. A range of management tactics are now being implemented to reduce the impact of the plant known as The Green Menace. The town of Hyde Park organized a committee, the Knot in Hyde Park Committee (KiHP), to train residents to identify the plant and learn how to control it. Their motto is “Act Early and Persist.” Their efforts began in May 2021, working on 27 sites over the season, ranging from single plants to a long stretch of knotweed along the Lamoille Valley Rail Trail.

In 2022, they added 30 sites, with 48 of the 57 under active management. By 2023, KiHP’s fieldwork continued “mechanical control,” repeatedly cutting or hand-pulling knotweed, and/or smothering with recycled rubber roofing, combined with pulling at the edges. KiHP managed 60 sites with an emphasis on early detection and stopping small patches from becoming established. That year, the herbicide glyphosate was applied as an experiment to evaluate whether chemical treatment should become part of the management program.

By 2025, the experiment with chemical treatment ended, with the assessment that the limited use of herbicides was effective, resulting in sites that were entirely free of knotweed or in a much diminished form (very short, multi-stemmed). An innovation for 2025 was the addition of three goats delivered to a site in North Hyde Park Village on May 31, to spend the season chewing on knotweed and rugosa roses. Volunteers monitored the goats daily. All of the Knot in Hyde Park detailed seasonal reports dating back to 2021 are available on the committee website.

While KiHP added goats to their arsenal of weapons in 2025, they had already joined the battle against knotweed in the towns of Warren, Waitsfield and Fayston, whose conservation commissioners decided to try unconventional approaches to address the issue. With support from the Friends of the Mad River, in 2024 the commissioners engaged the “goatscaping” service, The MAD GOAT LLC, cofounded by Mary Beth Herbert and Carole Parker.

Goats have a voracious appetite for knotweed leaves and young shoots to the extent that Japanese knotweed became over 50% of their diet that summer.
They foraged over ten acres of riverside land in three separate parcels from mid-June to mid-October. In 2024, each parcel was grazed three times during the season, roughly equivalent to cutting down the knotweed stands three times per growing season. In 2025, goats were brought into the parcels in early May when the shoots are young and succulent.

This process interrupts the regrowth cycle of knotweed and other invasives without the use of herbicides. (Similar programs are underway in New York, Massachusetts, Rhode Island and New Hampshire.) Mary Beth Herbert owns the goats and works as an independent grazing manager (shephard3.142@gmail.com). Mary specializes in invasive species removal and has nearly a decade of experience using sheep and goat grazing techniques to manage invasive species and restore lands. The fields in Warren and Waitsfield were chosen especially for their heavy infestation with mature knotweed.

The success of these experiments in 2024 and 2025 is providing optimism that goatscaping will evolve into a viable, successful business model that supports Vermont farmers and protects Vermont rivers and streams.

A new approach to containing and destroying knotweed comes from Britain, where Japanese knotweed is the most destructive and expensive invasive plant
to treat and control. The new approach involves hardware cloth. Simple instructions call for clearing the area to be treated, and covering it with ½-inch mesh
hardware cloth suspended slightly above the ground on stakes. The knotweed stems will grow through the mesh and become girdled, fall over, and die while eventually exhausting the rhizomes’ energy over multiple years. This method requires significant time, up to five years, and consistent monitoring to catch any new sprouts.

As a new approach in the US, it will take time to see whether this method is useful in the long term. There are numerous posts on Facebook, both pro and con, about this method. In Vermont, members of the Southeast Vermont Cooperative Invasive Species Management Association are experimenting with hardware cloth
control of Japanese knotweed in Windham County. VTInvasives.org features an article by Andrea Shortsleeve, the director of Operations for the Vermont Department of Fish and Wildlife, about this new approach.

Although Japanese knotweed remains a serious invasive plant problem for Vermont’s waterfront landscape, it is clear that several measures can be taken to treat and even control this particular threat.

Resources for more information:

www.uvm.edu: for intern experiences
Vermont Agency of Agriculture Food and Markets: for general information
Vermont Agency of Natural Resources’ LIEP Invasive Species Program
Vermont Department of Fish and Wildlife: for detailed descriptions and images of the plant, and treatment
and management options
www.vtinvasives.org: for treatment methods

This article was part of our Spring 2026 Newsletter.  We welcome ideas on newsletter content and article contributions.
Have some? We want to hear from you! Reach out to: deborah.miuccio@vermontlakes.org