In the mids, many people promoted the use of Oriental bittersweet for its hardiness and showy fruit which contributed to its popularity as an ornamental vine.
Oriental bittersweet is found in forested areas, field and forest margins, meadows, rights-of-way, fence rows, along waterways and in residential landscapes. This plant thrives in a range of soil types and light levels from full sun to shade.
Oriental bittersweet reproduces by seeds and rhizomes. The fruits are consumed, then dispersed by birds and mammals; ingested seeds have a higher germination rate than seeds that fall to the ground. People can move seed by using fruiting stems in flower arrangements. Oriental bittersweet is sometimes mistakenly labeled and sold by nurseries and in garden centers as American bittersweet. Oriental bittersweet vines twine around trees and other supports resulting in girdled and smothered trees and shrubs.
Entire plant communities may be overwhelmed by Oriental bittersweet. The added weight of the vines covered with snow and ice can break trees and shrubs. Oriental bittersweet outcompetes and displaces our indigenous American bittersweet to the point that Connecticut now lists the formerly common American bittersweet as a species of concern.
Farmland Protection Farmland Protection. Beneficial Insects Pollinators. Home Oriental Bittersweet. The management calendar for Oriental bittersweet emphasizes injuring the root system with late season foliar herbicide applications.
This may need to follow a cutting of the existing vines to force new, low-growing regrowth. Treating stumps at the time of cutting is an option but may not be practical. Prescriptions for controlling invasive Oriental bittersweet emphasize cutting the aerial growth to facilitate late season foliar herbicide treatments to injure the root system.
Hack-and-squirt, basal bark, and stump treatments can be made anytime the weather permits. Product names reflect the current Pennsylvania state herbicide contract; additional brands with the same active ingredients are available. Let's Stay Connected. By entering your email, you consent to receive communications from Penn State Extension. View our privacy policy. Thank you for your submission! Home Oriental Bittersweet.
Oriental Bittersweet. Oriental bittersweet Celastrus orbiculatus is an invasive, perennial, woody vine. This article displays images to assist with identification and provides recommendations for control, including a management calendar and treatment and timing table. Photo credit: Dave Jackson.
Background Oriental bittersweet Celastrus orbiculatus was introduced to the United States in the s from east Asia. Description Size Single vines can reach 60 feet in length, though it will only grow as high as the vegetation it is climbing. Leaves Distinctly round with toothed edges, the leaves are alternately arranged along the stem and between 3 and 4 inches in length. Flowers Oriental bittersweet is dioecious; pollen and fruit are borne on separate male and female plants.
Fruit Yellow-skinned fruit first appear on female plants in late summer. Stem Young growth is bright green; larger stems have red-brown bark that has a cracked, fish-netted texture. Look-alikes American bittersweet Celastrus scandens is a similar but far less common native species that is listed as rare or vulnerable in several states.
All photos by Dave Jackson Dispersal Oriental bittersweet reproduces by seed and vegetatively by sprouting from an extensive root system. Site While Oriental bittersweet prefers full sun, it tolerates dense shade while young. Control Though attacking the root system is the only way to kill the vine, freeing surrounding trees and other vegetation from the weight of the aerial stems by cutting them at ground level is typically the first step in controlling the vine.
Management Calendar The management calendar for Oriental bittersweet emphasizes injuring the root system with late season foliar herbicide applications.
Treatment and Timing Prescriptions for controlling invasive Oriental bittersweet emphasize cutting the aerial growth to facilitate late season foliar herbicide treatments to injure the root system. Waiting at least 8 weeks after initial cutting is typically sufficient. Rapidly growing shoots should be treated before they start twining around desirable trees and shrubs.
A surfactant e. If using a different glyphosate product, be sure to check the product label to see if a surfactant is needed; some come premixed. Basal bark applications wet the entire circumference of the lower 12 to 18 inches of the stem. Aim for full coverage on stems without creating runoff. Asiatic bittersweet is shade tolerant. However, like glossy buckthorn and common buckthorn, it frequently invades sunny areas which is why it is seen growing in open fields; along field, road and, path edges; and in any other areas that are sunny.
Ellsworth stated that Asiatic bittersweet has the genetic variability to tolerate a wide range of sun and shade exposures; high seedling survivorship was observed under deep shade; however, he also noticed that partially shaded conditions contributed to high seedling survivorship. Ellsworth as cited in Fryer reported that the thickness of the woodland litter layer affected seedling emergence; seedlings of Asiatic bittersweet were more successful emerging from pine litter layer than thick oak litter.
Pine litter has a structure more conducive to air and light penetration than the heavy matting effect that results from overlapping oak leaves. Asiatic bittersweet flowers from May to June; flowers are a greenish-yellow color Zheng, et al, Flowering time is the same as for common buckthorn. However, the fruiting period is quite long, beginning in July and lasting through October Zheng, et al, Like other exotic invasive plants this species has fruiting periods that are longer than most native plants in the landscape which increases its invasion success.
Cultural Controls: Monitor or visually inspect your property for Asiatic bittersweet. Do this at least every June and September. Do not plant, transplant, or encourage the planting of this species. Do not use this vine in the fruiting stage in holiday decorations particularly Christmas wreaths. Educating others e. Mechanical Controls: Pull, dig, and cut.
Pull out easy-to-pull plants. Spring or early summer cutting will slow its growth and reduce its ability to form functional male or female flowers for reproduction. Remember, this species is a dioecious plant with male flowers on one plant and female flowers on another plant. Cutting down Asiatic bittersweet vines in close proximity to one another before they flower disrupts an otherwise intact breeding system. In addition, the practice of repeated cutting on a monthly or so basis will be more effective at stunting the plant and inhibiting flower and fruit production.
Asiatic bittersweet twines around itself to create scaffolding, exhancing its ability to spread. Mechanical controls can be done at any time of the year; however, the best times are the months before or during flowering. Vines that have been cut at the base but are very large or entangled in the host vegetation should be left hanging in place for three to six months before they are pulled down. Freshly cut vines have a spongy or soft construct to their woody stems and need to dry out to become brittle enough to be easily pulled down without damaging host branches.
Fruit fate, seed germination and growth of an invasive vine - an experimental test of 'sit and wait' strategy. Biological Invasions 3: Konopik, Evelyn. McNab, W. Henry; Loftis, David. Probability of occurrence and habitat features for oriental bittersweet in an oak forest in the Southern Appalachian Mountains, USA.
Forestry Ecology and Management Miller, James H. Nonnative invasive plants of southern forests: a field guide for identification and control. Asheville, NC: U. News and Events Menu. Hoyle Asheville, North Carolina, is a hub for oriental bittersweet invasion.
Miller's recommended control procedures for oriental bittersweet : Thoroughly wet all leaves with one of the following herbicides in water with a surfactant July to October : Garlon 4, Garlon 3A, or a glyphosate herbicide as a 2 percent solution 8 ounces per 3 gallon mix.
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