The Derry Conservation Commission is partnering with the Information Technology (IT) Department to determine the scope of so-called “invasive plants” in Derry. Town of Derry IT Director Doug Rathburn attended the Aug. 12 Commission meeting to share what IT is doing to identify weeds.
The Commission is particularly concerned about Japanese knotweed, which is growing abundantly around town, Chairman Margaret Ives said – “on private roads, public roads, in wetlands, near homes.” Rathburn discussed how he is using the town’s GIS (Geographic Information System) mapping system to identify where knotweed and other invasives are growing. He contacted the University of New Hampshire and New Hampshire Fish and Game for their input.
Rathburn created an overlay map of Derry. About half the area, highlighted in red and orange, is invasive plants the state says the town should be concerned about. While they haven’t really taken root in town, they have the potential to do so, according to the state.
Looking at the map, member Dennis Wiley quipped, “It would be almost easier to map what we don’t have.”
The map doesn’t include knotweed at this point, but what Ives calls “the big three – bluntleaf privet, Gaines rocket and garlic mustard.” They are the plants the state thinks Derry should be concerned with, she said.
Member Jim Arruda is heading up the knotweed fight and brought in a sample of the plant. It’s the color of rhubarb, shaped like “crooked bamboo,” and grows to 4 or 5 1/2 feet, he said.
Ives noted that the roots of knotweed can go as deep as 30 feet, saying, “Once you’ve got a nodule in your yard….” And despite the “Big Three,” the Commission is concerned about the high proliferation of knotweed in Derry. “You drive down Island Pond Road, and it’s hard to find a spot where it isn’t,” Ives said.
There is a stand of knotweed near the Taylor Sawmill almost 100 feet long, member Richard Tripp said.
The Commission’s plan includes dividing the town into manageable parcels and having Commission members and Land Stewards each responsible for a section. They’ll go out and identify every place knotweed grows, then give the information to Rathburn so he can enter it in a map.
“The other three have not taken root in Derry,” Ives observed. “Knotweed has taken over.” “We need a starting point,” Wiley said. “It isn’t going to go away.” Rathburn said he would take Arruda out and teach him how to use the GPS. But the process has also been an education for him, Rathburn observed, adding, “Now that I’m aware of it (knotweed), I see it everywhere.”
