Extension Master GardenerSM Volunteers of Buncombe County

oriental bittersweet

Non-Native Invasive Plants: Oriental Bittersweet (Celastrus orbiculatus)

If you knew how awful it is, you would have nothing to do with oriental bittersweet! It is an aggressive, woody, deciduous, perennial vine capable of girdling stems and trunks of shrubs and trees, damaging their bark and underlying tissue. Despite its weedy behavior, oriental bittersweet is still sold and planted as an ornamental vine and should be avoided.

Oriental bittersweet vine chokes tree_photo by G. Merrill
Oriental bittersweet vine

Identification:

  • Leaves: Finely toothed, round glossy leaves are arranged alternately on the vine. They range from 2 to 5 inches long and 1.5 to 2 inches wide.

    Oriental bittersweet (Celastrus orbiculatus)_Leonara Ellie Enking_CC BY-SA 2.0_Flickr
    Oriental bittersweet foliage
  • Flowers: Clusters of 2 to 7 blossoms where the leaf attaches to the stem (leaf axil). Each flower has 5 petals and 5 sepals.
  • Fruit: Green-to-yellow round fruits ripen in the fall. Upon ripening, the fruits split open revealing three red-orange, fleshy berries that remain on the vine through the winter. The many birds and small mammals that feed on the berries distribute seed far and wide. A single plant can produce almost 400 fruits!

    Oriental Bittersweet_berries_Katja Schulz_CC BY 2.0_Flickr
    Oriental bittersweet Fruit
  • Distribution: Oriental bittersweet’s distribution ranges from central Maine south to North Carolina and west to Illinois;
  • Ecology: It can grow in woodlands, fields, hedgerows, coastal areas, and salt marsh edges. It tolerates shade but prefers full sun.

Management Options:

  • Mechanical control: Pull light infestations by hand—before fruiting, if possible. If fruits are present, bag the vines to make sure the seeds do not contaminate the site. Cutting the vines at the base early in the season will prevent flowering and fruiting, but you must remove all of the roots so the bittersweet will not re-sprout. Frequent mowing will also exclude oriental bittersweet, but infrequent mowing—two to three times a year—can stimulate root suckering.
  • Chemical control: You can successfully manage heavy infestations of non-native bittersweet with herbicides containing the active ingredient Triclopyr. The chemical is most effective applied immediately to the cut stem surface of cut or mowed vines. Apply herbicides prior to the emergence of native plants or after the last killing frost to help avoid herbicide contact with desirable plants. As with any herbicide, carefully follow the label guidelines when handling and applying.

American bittersweet (Celastrus scandens) is native to the eastern United States and is easily confused with oriental bittersweet. Leaf shape is highly variable and not a good characteristic for identifying American vs. Oriental bittersweet. Watch for flowers and fruits to distinguish the two:

  • American bittersweet flowers and fruits are only found at the ends of stems, Oriental bittersweet flowers and fruits are found all along the stem at leaf axils.
  • American bittersweet has orange capsules around red fruits, Oriental bittersweet has yellow capsules around red fruits.

A HOLIDAY CAUTION: Do NOT use oriental bittersweet in outdoor decorations! If you have any decorations containing oriental bittersweet fruits, be sure to bag them and discard—Do not compost!

Article by Bob Wardwell, Extension Master GardenerSM Volunteer

For More Information:

 

Weeds: The Worst Bad-Boy Climbing Vines

What is strong enough to climb 60 feet, can be 10 inches in diameter, cover a house, and kill trees, shrubs, and anything living standing its way? Would you believe vines? The three worst invasive vines in Western North Carolina are Japanese honeysuckle (Lonicera japonica), kudzu (Pueraria montana var. lobata), and Oriental bittersweet (Celastrus orbiculatus), according to the USDA National Agricultural Library, North Carolina Forest Service, and NC State University.

How did they get here and where are they now?
Good intentions gone bad! All three apparently arrived here during the 19th century as ornamental plant introductions from Japan.

Japanese Honeysuckle_David Helse_CC BY-NC 2.0_Flickr
Japanese honeysuckle

Japanese honeysuckle grows from Michigan to Florida and from the east coast to California. This shade-tolerant, evergreen, woody vine has elliptically shaped, opposite leaves. Its white or pale-yellow flowers appear from April to August, and glossy black berries are seen from June to March. It forms evergreen mats that shade out other plants. It spreads by seeds, runners—stems that grow horizontally, rooting in the ground producing baby plants—and rhizomes—modified roots that grow horizontally just under the surface of the ground. 

Kudzu ranges from New York to Texas and has made its way to Washington, Oregon, and Hawaii! Each leaf has 3 parts. The center leaflet has 3 lobes; the outer leaflets have 2 lobes each. Kudzu flowers from June to September, producing small lavender-to-purple, pea-like flowers that hang down in spikes, forming seed pods in the fall.

Kudzu_NatureServe_CC BY 2.0_Flickr
Kudzu

From 1935 through the early 1950s, the Soil Conservation Corps encouraged planting kudzu to help with soil erosion; roadside plantings proved particularly aggressive. Kudzu also grows in fields, disturbed forests, and forest edges, spreading through rhizomes and runners. Up to 100 feet in length, this deciduous woody vine can grow to 3 to 10 inches in diameter, killing other plants by growing over them. 

Oriental bittersweet has made its way to all states east of the Mississippi and much of the Midwest. This shade-tolerant vine can reach 60 feet in length and get up to 4 inches in diameter. It kills other plants by strangling trunks and stems, blocking sunlight, and generally weighing down them down! Birds spread its seeds. If you gather or purchase dried stems of bright yellow-red berries for decorative use, you may be contributing to the spread of this invasive by helping the berries/seeds find their way into the landscape or landfill.

Native American bittersweet note:
Not all bittersweet is an invasive weed! American bittersweet (Celastrus scandens) produces flowers and berries at the end of the stem, while Oriental bittersweet has flowers, then berries, along the entire stem. 

Vine control
With these weeds, the best defense is an aggressive offense! Don’t give them a chance to grow—pull them up when you spot seedlings. For older vines, removal is much more labor intensive and may involve cutting back—late summer is a good time—pulling up much larger root systems, smothering, mowing, or all of these techniques.

Herbicides are effective only when applied at the right time of year and even then, may require multiple applications. Remember to always follow label directions and be aware that these products may affect nearby trees, shrubs, flowers, grass, and vegetables.

Other invasive vines
NC State University also names the following vines as invasive: Cypress vine morning glory (Ipomoea quamoclit), English ivy (Hedera helix), porcelain-berry (Ampelopsis brevipedunculata), sweet autumn virgins bower (Clematis terniflora), winter creeper (Euonymus fortunei), and Chinese and Japanese wisteria (Wisteria sinensis and Wisteria floribunda).

Article written by Kay Green, Extension Master GardenerSM Volunteer.

Learn more
Invasive, Exotic Plants of the Southeast
by NC State Extension

American and Oriental Bittersweet Identification
by U. S. Geological Survey (USGS)

Herbicide control of invasive vines
by NC State Extension:
Japanese Honeysuckle 
Kudzu
Oriental Bittersweet

Additional removal methods:
Guide to Control Methods for 10 Common Western North Carolina Riparian Weeds
by RiverLink Volunteer Corinne M. Duncan

Surgical Crown Removal of Kudzu
by KOkudzu.com: “Knock Out Kudzu”

Backyard Bullies, Part II

 

rira-BJSo, on your homestead you’ve got kudzu, Oriental bittersweet, great big clumps of Miscanthus (Chinese silvergrass) and some bullies that you’ve not yet been able to identify but you know from the way they’re behaving that they’re indeed bullies, not something you want in your landscape. Fall is a great time of year to take or plan to take the first steps toward eliminating them.

You do have a variety of options and some work better than others for a particular bully so the first step is to identify them. If you need help you can always bring us a sample, a branch with several leaves and maybe the fruit. If you’re sure of the name give us a call and we can discuss which option should work best for you.

And here are your basic options to consider:

Break the reproductive cycle. This works best for annual or biennial plants, plants that go through their entire life cycle, from seed to flower to seed in one (annual), or two (biennial) growing seasons. One way is to prevent the seed from germinating in the first place. This is the approach many homeowners use for treating annual weeds in lawns. There are also natural and chemical pre-emergent treatments available. Or, in small areas you can make a practice of cutting off the flowers by hand before they go to seed. Bag those flowers for the landfill rather than putting them in your compost.

Another option is exhaustion, wearing the plant out by using up all of its energy and preventing it from growing at all by frequent mowing for example. Goats can do the same thing, and there are a number of local folks in the rent-a-goat business. Flame, torching the plant to the ground is another option but can be a fire hazard.DCP_0891-2

Physical removal of the plant by manually pulling or disking with a machine or tiller may be appropriate in some cases or with some species but not for others. It’s important to not leave any pieces of the root in the ground or you’ll likely have a reappearance.

Finally, we have the option of using a chemical herbicide. These are classified by their mode of action (MOA) or how they actually work. Some are contact, damaging tissues they actually touch, while others are systemic and kill from within after being absorbed into the plant through the roots or leaves.

Selective chemicals may work, for example, only against grasses but not broadleaf plants or vice versa. 2,4-D which kills broad leaf plants like dandelions in a lawn without harming the grass for example, is a selective systemic. Glyphosate, aka Roundup will kill any plant, including your lawn.

Now, after a full season of growth, is the absolute best time of year to get out and look for new bullies in your yard, garden or woods or along the road. Plants that are taking over, climbing on their neighbors, acting like genuine BULLIES.

Call us for help in identifying and in choosing your course and timing of your bully-busting campaign. 828-255-5522.

Written by Glenn Palmer

Contact Us

Buncombe County Extension Office
49 Mount Carmel Road
Asheville, NC 28806
Helpline 828-255-5522

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