On an unusually sultry September day, Deane Van Dusen of Biome Care is evaluating a small stand of apple, ash and birch trees at the Tarr-Eaton farmhouse in Harpswell Neck.
"This is where the worst infestation is," he says as he circles the stand of trees to find Tatarian honeysuckle.
Van Dusen says this large stand has probably been growing here for 40 years, and he will use a treatment to kill the shrubs. He says the honeysuckle, left unchecked, will take over this grassy field and those beyond it that provide habitat for birds such as the bobolink and eastern meadowlark, food for wild animals like foxes and rabbits, and native milkweed for monarch butterflies.
Van Dusen saws the woody shrubs down to stumps and then mixes a 50/50 solution of Triclopyr and water to paint on the stumps. He says the application must be done within an hour of cutting it down so plant secretions don't seal the stump and block the herbicide from seeping in and killing the honeysuckle.
Van Dusen is a licensed master applicator who is authorized to use Triclopyr, which he says is the most effective herbicide for woody shrubs like honeysuckle, especially when you apply it in the fall.
"In the fall the plants are storing energy in the root system. They're making sugar through photosynthesis and sending it to the roots. So by treating the plants at this time you're getting a good translocation of the herbicide into the root system and that's just what you want," Van Dusen said.
Using chemicals on invasives is the last resort, according to U.S. Environmental Protection Agency Integrated Pest Management best practices. The most economical and the preferred approach is one that has the least harmful effects on people, land, and the environment.
Van Dusen says native plants can smother invasives and points out some massive fox grape vines growing on the other side of the farmhouse. The vines are blocking the sun for the honeysuckle and it's dying off.
Maine State Horticulturist Gary Fish says native plants are also critical for insects and other wildlife.
"Some plants host specific bees and other pollinators. Others are hosts for caterpillars and moths that feed baby birds and things like that," Fish said.
Down the road on Bailey's Island near Mackerel Cove is Johnson's Field Preserve, where numerous native plants and the invasive Morrow's honeysuckle grow.
Becky Gallery of the Harpswell Invasive Plant Partnership pushes through Rugosa rose bushes to expose black plastic bags sealed over cut honeysuckle stumps to kill them off. Gallery says the partnership is limited to hands-on methods of control here because Harpswell bans the use of herbicides within 25 feet of water.
"We use chemical means when we are far enough from water, if nothing else works. So it's dig, cut, pull and repeat, and sometimes it's a year after year effort," Gallery said.
A conservation easement on the land held by the Harpswell Heritage Land Trust requires that the honeysuckle be cut down because it blocks the view of the cove.
Gallery says there is a native version of honeysuckle, so it's important to know which honeysuckle variety you have before cutting a plant down.
"Native honeysuckle would be just a solid white across the middle of the stem. So we've got this dark spot in the middle and the opposite leaves so this is the invasive version with the dark pith," she said.
Honeysuckle, introduced as ornamentals in the late 1800s, now threaten much of Maine's ecosystem. Conservationists say it's up to all landowners to be vigilant to stop their spread.
Visit this Maine Department of Agriculture, Conservation and Forestry page to learn more about invasive plants that could be in your yard or home town.
Support for Deep Dive: Invasives is provided by Maine Audubon, Friends of Acadia and Coastal Maine Botanical Gardens.
