Oriental bittersweet quickly naturalized in many areas. The vine is an aggressive invader, growing over vegetation. This bittersweet covers and kills native plants by blocking sunlight, weighing the plants down, and girdling stems and trunks. Despite its weedy behavior,oriental bittersweet is still planted as an ornamental vine.
Non-native bittersweet is a deciduous vine that can grow into the tops of trees. The finely toothed, round leaves are glossy and alternately arranged on the vine. The plant flowers in the spring and bears clusters of small greenish flowers that emerge from the leaf axils. The globular green to yellow fruits ripen in the fall. Upon ripening, the fruit splits open revealing three red-orange, fleshy arils, or berries. The berries remain on the vine through the winter. The seeds are distributed by the many birds and small mammals feed on the berries.
Climbing bittersweet (Celastrus scandens, L.) is native to the eastern United States and is easily confused with oriental bittersweet. The native bittersweet flowers at the tip rather than along the stem. Because native bittersweet is beneficial, consult a natural resource professional to properly identify bittersweet before implementing control plans.
Oriental bittersweet's distribution ranges from central Maine south to North Carolina and west to Illinois. Non-native bittersweet grows in woodlands, early successional fields, hedgerows, coastal areas, and salt marsh edges. Bittersweet thrives in moist to semi-moist soils but has also been found growing vigorously in sand dunes along coastal areas. This vine tolerates shade very well, but prefers full sun.
Mechanical control can be used to remove light infestations of oriental bittersweet. The vine can be pulled by hand and removed from the site. Pull the plants before fruiting. If fruits are present, bag the vines to make sure the seeds do not contaminate the site. Also take care to remove all of the roots because the bittersweet will resprout if roots are left. Frequent mowing will exclude oriental bittersweet, but infrequent mowing--mowing two to three times a year--stimulates root suckering.
Glyphosate and triclopyr herbicides have been successfully used in bittersweet management. These chemicals are most effective if the stems are cut by hand or mowed and the herbicide is applied immediately to the cut surface of the stem. Herbicides should be applied prior to the emergence of native plants or after the last killing frost. Avoid herbicide contact with desirable plants. If desirable grasses, sedges, plants belonging to the lily family, or other monocots are present consider using triclopyr because this herbicide does not kill monocots. As with any herbicide, consult professionals before using the product and carefully follow the label guidelines when handling.
Prepared by Anne T. Lenox, Forest Resources Extension staff member and undergraduate in Forest Science
The first picture is used with permission from the National Park Service. The second and third pictures are used with the permission of © John Randall/The Nature Conservancy.