Alien invaders in West Virginian backyards: Battling the Japanese knotweed plant
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In 2009, a Service biologist discovered a non-native plant invading the Thorn Creek watershed in eastern West Virginia, smothering native plants and damaging creeks, farms and gardens.
The plant, Japanese knotweed, is a large, aggressive non-native perennial that grows quickly and densely along riverbanks. When in bloom, the small white strings of flowers and bamboo-like hollow stalks give it a misleading attractiveness. This pretty plant has an ugly side, defeating its native neighbors and rapidly expanding from one stem to densely packed, acre-wide stands that can survive the state's cold winters.
"This invasive is so powerful, you can cut off a small piece, let it float down the river, and wherever it lands, it will take root," said John Schmidt with the U.S. Fish and Wildlife Service in West Virginia. "It spreads vegetatively—through just a piece of it, like the root—and by seeds."
The Service, working collaboratively with the Potomac Highlands Cooperative Weed and Pest Management Area, immediately began to work against this invasive.
An AmeriCorps member working with the Service met with landowners in the Thorn Creek area in 2010 to get permission to survey and treat the watershed.
Landowners were very willing to assist with this coordinated effort to improve their lands for people, plants, fish and wildlife. This invasive puts those resources at risk, weakening stream banks and making them more apt to flood private lands. It also jeopardizes the food sources for wildlife living in and around the streams, including the brook trout populations that are popular for fishing.
"When we tell landowners that their West Virginia native vegetation is at risk, they take pride in restoring that," said Schmidt. As the state coordinator for the Service's West Virginia Partners for Fish and Wildlife Program, Schmidt often works with private landowners. "We can help people take charge of their resources and reap the benefits. We can give community members the tools they need to become better stewards of the environment."
Harlon Mitchell, a landowner who helped the Service work on his Thorn Creek property, said he wanted to get rid of the invasive knotweed anyhow.
"You couldn't get down to the creek," he said. "The plant covered up all the banks by a good fishing hole."
Other landowners are also eager to rid their properties of this plant that takes over their yards, creating stands that are up to 10 feet high.
We need your help to battle the knotweed
The Partners for Fish and Wildlife Program, administered by the U.S. Fish and Wildlife Service, works with private landowners to improve their properties for fish and wildlife, which in turn also benefits the land use for owners.
This program and its partners work through this collaborative effort to offer free assistance to help detect and control invasive plants on private lands. But our program needs assistance from landowners and their neighbors.
A coordinated effort is extremely important, as destroying a patch of knotweed in one area, without treating it on neighboring lands, will hinder control efforts and likely result in return of the invasive knotweed. The Service's West Virginia Field Office is available to set up a time to visit with you to talk about how we can help.
Here's how we attack knotweed
Properly timed treatment is essential to get rid of Japanese knotweed. Below is the best method to remove this invasive:
By the end of June, cut the plant to the ground. Leave cut plant material, and make sure that no parts fall into a waterway.
Between August and mid-September, spray the plant with an appropriate glyphosate-based herbicide, such as Rodeo, that is approved for use near water. Commercially available Round-up is not an appropriate herbicide for plants in or near water.
Any surviving plants can be retreated in early July in following years.
Since the invasive can spread with speed and ease, it's necessary to work on large areas at the same time. Cutting the knotweed forces the plant to use its stored energy for re-growth and increases the efficacy of herbicide.
Follow-up tours of the treated watershed have shown that the pesticide treatment was successful to some degree at every site. But we expect to repeat treatment and begin restoration during the next two to three years.
After knotweed is eradicated, the Service will help restore sites by planting vegetation. Native plants help stabilize the banks and filter the pollutants that enter the water. Fences can help maintain the stabilization of these banks and avoid erosion. This work improves the habitat for wildlife, protects crop, hay and cattle production, and it decreases the need for fertilizers and pesticides.
Where we are working now.
The Service finished one field season working at Thorn Creek and is returning to check on those sites. The first round of pesticide was 80 to 90 percent effective. We will assess the need for continued treatment.
Since the summer of 2011, Partners for Fish and Wildlife have been working with additional landowners in the Seneca Creek watershed in Pendleton County, West Virginia. This work continues.