Controlling Fruit-bearing Invasive Plants

Porcelainberry. Photo ©2025 by Leslie J. Mehrhoff, Bugwood.org

Invasive plants that produce fruits must be dealt with during the summer months before their fruits ripen. Otherwise, birds and other animals will spread the seeded berries into new areas, sometimes over great distances. The territory of an overwintering bird like our Northern Cardinal can be up to ten acres. Of course, birds that migrate in fall will spread seeds much farther. The issue with invasive plants is that they are displacing native vegetation essential for many wildlife species. Fruit-bearing invasives of concern include Japanese Barberry, Burning Bush, Autumn Olive, Mile-a-Minute vine, Wineberry, Porcelainberry and Oriental Bittersweet vine.

Oriental Bittersweet vines attached to trees. Photo ©2025 Richard Gardner, Buwood.org

Invasive plants are very aggressive. Leafing out earlier than native species combined with prolific fruit/seed production, gives them a huge advantage for growth and reproduction. Many invasives create monocultures to crowd out other vegetation (Barberry, Burning Bush). Others cover and smother vegetation (Mile-a-Minute, Porcelainberry (pictured). And, many invasive plants also reproduce vegetatively as stems arch to the ground to produce new plants (Wineberry).

Oriental Bittersweet (Celastrus orbiculatus) is a tree killer. This invasive vine is extremely destructive. It climbs with twining stems to strangle the limbs of shrubs and trees, growing to great heights in search of more light. Vines can get huge, several inches in diameter and their weight can uproot and topple trees. Primarily spread when seeded berries are dispersed by birds, bittersweet can also reproduce by root suckering. Two native vines that climb but do not harm trees are poison ivy, “leaves of three, let it be” and Virginia creeper, “leaves of five, let it thrive.” Both these vines are immensely beneficial to wildlife. However, poison ivy is considered a “problem native” due to the allergic reaction it causes in humans.

Bittersweet vine is common an easily identifiable. Young plants send out “tentacles” that wrap around any tree, shrub or object they encounter. When pulled or dug, bittersweet reveals its distinctive bright orange roots. In late summer, fruits unlike any other, have a yellow outer shell that opens to a fleshy red seed covering.

Controlling Oriental Bittersweet – as always, early detection is important. Small sapling plants can be easily removed by pulling or digging when the ground is moist, making sure to remove the entire root. Cutting alone will not provide effective control as it stimulates resprouting, however cutting will reduce its destructive effects to trees and shrubs for the short term. Vines above the cut are best left in place since pulling will damage tree branches. Dead vines will eventually deteriorate. The CT Invasive Plant Working Group recommends cutting and painting with an herbicide during the growingseason to control Oriental Bittersweet. Penn State Extension is another excellent source for information on controlling bittersweet and other invasive plants.

Disposal of Invasive Plants – Invasives without mature berries/seeds can be placed in a brush pile. If mature berries are present, plants should be placed in a designated area where they can be monitored for reseeding or bagged for incineration. Invasives with berries or seeds should never be placed in a compost pile or in the brush area at the Town Transfer Station.

The Invasive Insider is published quarterly in cooperation with The Newtown Bee by the Newtown Conservation Commission.

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