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A multi-year project has started to eradicate invasive purple loosestrife encroaching on Walker Pond, a popular summer destination in the towns of Sedgwick and Brooksville.
The plants flower in Maine starting in late July and produce millions of tiny seeds that travel easily and remain viable for years. Purple loosestrife is especially good at taking over wetland areas, where it pushes out native species.
A resident spotted them at the Mill Pond, a small water body connected to Walker Pond on the north side of Route 175, and alerted the town of Sedgwick. Alex Cammen, a hired invasive species specialist, will work to eliminate it over the next few years.
The project will help preserve native plants and the food and habitat they provide for wildlife, showing how early action can help stop invasive species from spreading. Walker Pond hosts swimming, boating, paddling and fishing and is home to a summer camp; if the invasive flowers spread, they could also take over that pond’s shoreline.
An area with dozens of native plant species offers food and habitat for insects and wildlife within a healthy ecosystem, Cammen said. Invasive plant species generally push out those other plants and the various resources they provide.
In its native ecosystems across the Atlantic, loosestrife proliferates when a disturbance like a flood opens up new ground. But there, weevils eventually knock it back, a species that’s not present in Maine. Elsewhere in the U.S., the flowers have been controlled with the introduction of beetles that prey on it.
Human use of Walker Pond could also become more challenging if the loosestrife crossed Route 175 and became established on the shore, Cammen said. It could crowd out native cattails, grasses and sedges at the boat launch and create more maintenance work for a channel connecting the two ponds that people use to move canoes.
Purple loosestrife isn’t a common problem in Hancock County, according to Cammen; it’s better established in southern Maine and farther Down East, he said. He gets more calls about Japanese knotweed, multiflora rose, asiatic bittersweet, buckthorns and shrubby honeysuckles.
It’s a mystery how the purple loosestrife arrived at the Mill Pond. Cammen believes seeds may have traveled in the mud on a visitor’s boots, a common way that invasives spread — and a reason why he encourages people to clean their shoes.
The plants at the Mill Pond cover an area about 20 feet wide and 100 feet long, a small enough area that he expects to be able to eradicate it in a few years, unlike larger plant populations.
Other invasives are already established there, particularly multiflora rose surrounding the stream exiting the smaller pond.
“The reason this [purple loosestrife] site was found was just because someone brought it up to the town,” he said. “It’s really important for people to know what some of these invasives look like.”
Cammen removed the seed heads left over from last season in May. When the plants bud in July, he’ll return to wipe the stems with the glyphosate herbicide AquaMaster to stop most of them from producing seeds again, depending on state approvals.
The water-soluble herbicide breaks down quickly and is nontoxic to animals and plant life, according to Cammen. It doesn’t travel in soil and won’t leach out underwater or into the pond, he said. Applying it with a brush will keep it from spreading elsewhere.
In September, he’ll return to collect seed pods, and continue the process for two more years with whatever plants remain.
The control work is $100 in the first year and less in the following, he said. The two towns will split the cost, according to Sedgwick select board minutes. Town officials couldn’t be reached Friday for comment.
While treating the invasive plants, Cammen will put up signs and close the side of the Mill Pond for several days out of an abundance of caution, though there’s no threat to the public from the AquaMaster, he said.
Catching invasive plant populations early also helps get a handle on how quickly they spread and how common the plants can become, Cammen said. Seeds are easily carried by birds and can travel.
The Maine Natural Areas Program produces a guide to identifying invasive species. He also advises reaching out to the program or local invasive control specialists if anyone spots some.
“It really takes everyone working to control it,” he said.
