PORTLAND — Land trusts and nurseries are applauding a move by the Maine Department of Agriculture, Conservation and Forestry to prohibit the sale and distribution of 33 invasive plant species.
“The plants on this list have invaded farms, fields, forests and wetlands throughout the state,” Walt Whitcomb, commissioner of agriculture, said in a press release.
“Although many were originally promoted with good intentions, they have spread throughout Maine to the detriment of native species,” Whitcomb added. “In many places they have come to dominate forests, wetlands, fields and local landscapes, excluding native plants that support our economy and natural areas.”
The new rule went into effect in mid-January, but the prohibition on sales does not begin until Jan. 1, 2018. Meanwhile, the department said, there are many non-invasive alternatives available to help homeowners and nursery professionals satisfy their landscape needs.
The banned plants were reviewed by a special committee of horticulture professionals, land managers, foresters, wildlife biologists and other scientists, according to the Department of Agriculture.
The plants mostly include a wide variety of bittersweet, honeysuckle, and barberry, along with purple loosestrife, western lupine and multiflora roses.
Gary Fish, the state horticulturist, said the plants are being banned because they “are a direct threat to what we value about Maine’s natural and working landscapes.”
And, he said, “The aggressive growth of invasive plants increases costs for agriculture, can affect forest regeneration, threatens our recreational experiences, and reduces the value of habitats for mammals, birds and pollinators.”
Fish added, “Invasive (plant) species are the second-greatest threat to global biodiversity after loss of habitat. Invading plants out compete native species by hogging sunlight, water, nutrients and space.
“They change animal habitat by eliminating native foods, altering cover and destroying nesting opportunities. Some invaders are so aggressive they leave no room for our natives.”
To be considered an invasive plant, Fish said the species must be non-native to Maine; have the potential for rapid growth and widespread dispersion; have the potential for existing in high numbers, and have the potential to displace native species.
Nurseries around the state have been informed about the 33 plants now banned, he said, and they have the remainder of 2017 to sell those plants or return them to wholesalers.
After Jan. 1, 2018, “we will be providing warnings and, if they do not remove the plants from their sales areas, we could impose up to a $500 fine for each violation,” Fish said.
Most professional nurseries and landscapers in Maine have been expecting a ban on invasive plants for several years, according to Fish, and “the majority already have stopped selling these plants. They also understand the impact these plants can have on trails, forests and farm fields.”
He said the biggest hurdle “is to convince homeowners that there are great alternative plants to ones they commonly request like crimson king maples, burning bush or barberry.”
Homeowners who already have these plants in their gardens or landscapes, Fish said, should consider replacing them.
Chad Skillin of Skillins Greenhouses, which has locations in Falmouth, Cumberland and Brunswick, said overall “we feel the state has put a lot of time into developing criteria that is just and fair.”
He said the invasive plant ban should not impact his business, as “most of the plants on the list are ones we have phased out of our inventory already or haven’t been available for sale for years.”
Skillin also said, “We have good alternatives and should be able to meet all our customers’ needs. We are confident we can provide adequate substitutions that accomplish the same things as the invasive plants now prohibited.”
Jeff O’Donal, of O’Donal’s Nursery in Gorham, agreed with Skillin. “I firmly believe it is about time this happened,” he said. “… We have been aware for some time of invasive plants encroaching on Maine’s valuable natural areas.”
O’Donal said his was the first garden center in Maine to stop offering problem plants like barberry, autumn olive, shrub honeysuckle and bittersweet vines.
Even so, he said, “We are disappointed that all forms (of certain species) are in the invasive portion of the ruling. (I told the) Legislature in 2011 that having an invasive plant law in Maine should not keep gardeners from being able to procure plants that are not invasive and are well-behaved.”
But, O’Donal also acknowledged that the new rules would “without a doubt have the positive result (of) increasing demand for garden plants native to Maine.”
Like her counterparts at the other local nurseries, Genevieve Coombs at Roosevelt Trail Landscape & Garden Center in Windham said she supports the “movement to eliminate invasive plants from the landscape.”
“We actually took the responsibility of eliminating the number of potential invasives in the landscape many years ago,” Coombs said. “We were proactive and stopped selling the plants on this list about 12 years ago, so we don’t foresee any impact on our current sales.
“We have offered alternatives for many years,” she continued, “and 95 percent of our customers are quite happy with the options (available, especially) once they hear about the potential for environmental impact from the invasive species.”
Jennifer Grimm, executive director of the Falmouth Land Trust, said the ban is an “important first step in increasing the public’s awareness of invasive species and the impact they can have on our landscape and biodiversity.”
The problem, she said, is “once invasive species are in the environment, there are a lots of costs associated with addressing and removing them.”
“The threat of invasive species is a problem for all landowners,” Grimm added. “Time and money are the biggest factors that make the removal of established invasive species so difficult.”
When removing invasive species, Grimm said, “We use the best practices available. Oftentimes that’s a combination of mechanical and chemical techniques. Effective and complete eradication typically involves both, as well as follow-up and monitoring.”
And, like Fish, she said “there are important reasons for being concerned about invasive species. When invasive ones replace (native) species, it has a ripple effect throughout the ecosystem.
“This affects our pollinators, our birds, bats, and even our waterways, which can be choked by (invasive) plants that can make it nearly impossible for our local species to thrive.
“The public is a key and important line of defense, and planting native species is a great way to support our local biodiversity and keep our ecosystem healthy.”
Angela Twitchell, director of the Brunswick-Topsham Land Trust, said nearly all of the trust’s properties and easements are impacted by invasive plants.
“Infestations of honeysuckle, barberry and bittersweet are widespread on some properties and are clearly crowding out native species,” Twitchell said, which is why the trust was fully in support of the ban.
“The existence of the ban will be a tool that organizations can use to educate the public about the negative impacts of invasives,” Twitchell said.
Daniel Bishop, the stewardship and trail volunteer coordinator for Portland Trails, said, “Controlling invasives is a long term and very laborious task,” but one that “is important to enhancing the habitat value.”
He said Portland Trails has begun to develop a comprehensive invasive management plan, which involves manually removing, cutting and preventing further spreading.
“It is important to both control and ultimately remove these invasives to increase biodiversity,” Bishop said. “Biodiversity is a key indicator of habitat health. In some areas, such as wetlands, (the spread of invasive plants) can dramatically change how that wetland functions.
“Invasives can also have greater impacts on sensitive or threatened habitats and species due to how easily they spread. (And) other invasive species can adversely affect human health.”
For instance, Bishop said, “it’s been proven that some invasives harbor significantly more ticks per acre then native (plants).”
Kathy Mills, director of the Scarborough Land Trust, is also fully on board with the invasive plants ban.
“Invasive plants degrade healthy ecosystems by crowding out native plants, providing insufficient nutrition and sometimes toxins to birds and insects, and severely reducing beneficial biodiversity,” she said.
“Most of the worst invasive plants in Maine were brought and planted here deliberately, so halting the introduction of more is critical in helping to stop their spread.”
On some Scarborough Land Trust properties “we have many invasive plants and we are working on developing strategies to deal with them,” Mills said.
Those efforts include cutting and removing invasives, “which we will need to do over several seasons to have a permanent effect. Many biologists consider invasive species to be the second-biggest threat to biodiversity worldwide, so it’s important that our preserves are part of a solution to this problem.”
Mills said while efforts by land trusts, state agencies, and other organized groups are essential, “a truly meaningful response to invasive species needs to involve independent actions by individual landowners.”
Japanese barberry is now listed as a banned invasive species in Maine.
Many varieties of honeysuckle, including the Morrow’s honeysuckle, are considered invasive plants no longer welcome in Maine.