This story was originally produced by The Keene Sentinel. NHPR is republishing it in partnership with the Granite State News Collaborative.
Glossy buckthorn, Japanese knotweed and Asian bittersweet are just a few of the invasive plant species that keep New Hampshire State Rep. James Spillane up at night.
The Deerfield Republican, chairman of the House Fish and Game and Marine Resources Committee, is leading an effort to develop a coordinated statewide strategy to combat plants that were brought to New Hampshire from other parts of the world, grow like wildfire and outcompete native vegetation.
Among other things, that effort will involve public outreach, mapping and identifying funding sources.
A working group of legislators, state agency representatives, landowner organizations and academic experts met twice last month on this issue, Spillane said in a recent interview.
Future legislation is a possibility being considered.
“Terrestrial invasive species are expanding in every corner of the state,” Spillane said. “They damage our forests, farmland, roadways, and even our wildlife habitat. We must get ahead of this problem with a unified, statewide approach.”
Take Asian bittersweet, for example.
“I got a complaint myself specifically from the gentleman who runs all the cemeteries for the Catholic church in New Hampshire,” Spillane said. “They’ve had Asian bittersweet take over cemeteries. In one case, it had embedded itself into the wall of a neighbor’s barn and they had to replace the wall to rip it out.”
The extremely aggressive vine was brought to this country in the mid-1800s as an ornamental plant, according to the University of New Hampshire Extension’s website.
Japanese knotweed was also introduced in the 1800s as an ornamental. It can grow through asphalt and concrete and reach 9 feet in height. Its underground structure can extend 10 feet deep and 40 feet long. The plant can regenerate if even a half-inch of it isn’t pulled up, the website says.
Glossy buckthorn, native to Eurasia, began spreading in New Hampshire in the 1900s. It was initially introduced as a hedge, but it creates dense thickets and outcompetes native plants.
Another invasive of concern is the mile-a-minute weed, another Asian vine that can grow more than 6 inches in a day.
Steven Roberge, a UNH Extension specialist who lives in Peterborough and works across the state, said the first step in limiting the spread of invasives is identifying them. Some invasives hold on to their leaves longer than native plants, so they tend to stand out in the fall.
“The sooner you can identify an invasive plant on your property, the easier it is to manage that plant,” he said.
“If you have a couple of stems, all it would take is hand-pulling. But if you get to the point where there are thousands of stems, or they are very old, very big, very established, that becomes a difficult process to control those plants at that point.”
If herbicides have to be applied, it is best to do it in a focused, targeted way, so other plants aren’t harmed, Roberge added.
Late summer is a particularly good time to apply pesticides to leaves, he said.
“If you imagine a plant in the springtime, it is pushing nutrients up and it is growing and extending,” Roberge said. “The second half of the growing season is a time when they are actually bringing things back down for storage.”
Herbicides work most effectively later in the growing season when the chemicals are more readily brought down to the plant’s roots, he said.
The state needs to remain vigilant about newer invasive plants that have come on the scene, or haven’t yet reached the state, Roberge said.
To limit the spread of invasives, Spillane wants to:
- Expand education and public outreach on identifying and reporting invasives.
- Improve efforts to map where invasives have spread.
- Encourage towns to maintain licensed herbicide applicators.
- Explore state and federal funding sources.
Investigate whether the state can reduce costs through bulk purchasing of herbicides.
The ultimate goal, he said, is to “identify, isolate and eradicate invasives.”
“This is about protecting New Hampshire’s natural resources for future generations,” he added. “We’ve taken the first steps, and much more work lies ahead.”