Don’t be fooled by its pretty orange berries: the Asian bittersweet is a nasty gas

Don’t be fooled by its pretty orange berries: the Asian bittersweet is a nasty gas

Found throughout New England, it is an aggressive climbing vine that grows wildly out of control along roadsides, and can topple trees and take over entire forest patches. Asian bittersweet (not to be confused with the American variety) removes trees, shrubs and native plants. If there’s a vacant building in your neighborhood, the vine has likely left its mark.

And don’t be fooled by the attractive yellow-orange berries in the fall: this plant is one of the worst.

You can call it a “super spreader.” I first learned about this through a Facebook post. Someone shared a photo of the vine’s shiny, round, finely toothed leaves and I realized that not only did I have bittersweet in my garden, I was seeing it everywhere — on walks in the neighborhood with my dog ​​and on recent road trips to Massachusetts and New York.

And its bright berries that are so popular for making wreaths in the fall? Birds love them too.

Birds can eat the orange-red berries of Asian bittersweet, dispersing the seeds in their droppings.

Maine Natural Areas Program

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Maine Department of Agriculture, Conservation and Forestry

Birds can eat the orange-red berries of Asian bittersweet, dispersing the seeds in their droppings.

“Almost every berry a bird eats because it’s bright orange, they release the seeds and there’s another plant,” says Rick Gammon, a horticulturist who runs a landscaping company based in Auburn, Maine.

He says a lack of public awareness is another reason behind the prolific production. If left unchecked, they can climb 60 feet or more to treetops and crawl across the ground in a monstrous mass, choking everything in their path.

“People don’t do anything,” Gammon says. “It wouldn’t be so bad if people took control of it. There would be no seed factory. There would be no product for the next generation.”

So, in some cities like Auburn, they’re trying to go after it.

The invasive Asian bittersweet plant sends up an aggressive climbing vine that can help it grow wildly out of control along roadsides, toppling trees and taking over entire forest clearings.

Maine Natural Areas Program

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Maine Department of Agriculture, Conservation and Forestry

The invasive Asian bittersweet plant sends up an aggressive climbing vine that can help it grow wildly out of control along roadsides, toppling trees and taking over entire forest clearings.

“If you come here, you can see how the oak tree is climbing. It’s already been cut down. So, we’re going to try to cut that down,” says Dave Griswold, during a recent workshop in a city park, with thunder in the distance.

Griswold, a licensed forester, shows residents how to identify bitter sweets, how to pull or dig them out of the ground and use shears to cut vines at ankle and chest height.

Using some muscle, Griswold and others work together to extract this particular culprit and all his roots.

It’s a huge collection of bitter sweets wrapped around a bunch of oak trees. If left alone, the vines will thicken and wrap around trees, suffocating them as they ascend toward the sun.

“We’re definitely not going to solve the problem here, but we’ve made some progress anyway,” Gammon says.

But getting rid of bittersweet, like many other invasive plants, takes years of persistence and a combination of methods.

“When we bought our property a year ago, there were some vines about the size of my arm that we had to cut and manage, and they keep coming back,” says Auburn resident Mary Caron.

Caron says she came to the workshop to make sure she was doing everything she could to combat bitter sweets. I have already lost some trees that have weakened under the weight of the vines.

“We had some things covered in it to the point where we ended up cutting it off because we didn’t want it falling on our house and we didn’t want it falling on our property and so forth,” Caron says.

The leaves of the Asian sweet plant are round with slightly serrated edges, and its fruits appear green before maturity.

Maine Natural Areas Program

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Maine Department of Agriculture, Conservation and Forestry

The leaves of the Asian sweet plant are round with serrated edges, and their stems appear green in the spring.

Caron says she avoided using herbicides that can be applied to freshly cut stems in the ground, but can harm other native species. Even with mechanical removal methods, the sweet stuff is still likely to come back.

Native to East Asia, it was brought here as an ornamental plant over a hundred years ago, and is still used in some places. However, it is now considered so invasive that its sale has been banned in several New England states, including Maine.

Back in my own garden, gardener Rick Gammon gave me the bad news: “I see well-established bittersweet vines growing on your ornamental plants — wild apples, cherries, oaks — and if left to their own devices, they could kill all of those plants.”

Well, we won’t let that happen. Therefore, we developed a plan that included extensive pulling and cutting at least twice a year. When it comes to managing invasive plants like bittersweet, Gammon and others say it’s all about thinking globally and acting locally — and by all means, spreading the word.

Patti White contributed reporting.

Support for Deep diving: invasive They are provided by Maine Audubon, Friends of Acadia, and Coastal Maine Botanical Gardens.

A pile of invasive Asian bittersweet plants was removed during a recent workshop in Auburn.

Patti White

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A pile of invasive Asian bittersweet plants was removed during a recent workshop in Auburn.

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