Extension Master GardenerSM Volunteers of Buncombe County

Invasive Plants

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:

 

Non-Native Invasive Plants: Tree of Heaven

Once you learn about non-native invasive plants they seem to be everywhere! One of the worst of these—Ailanthus altissima—has the misleading common name “Tree of Heaven.” Introduced as an ornamental, Ailanthus is an attractive, fast-growing tree—but when cut back it can sprout up more than 10 feet a year! Water and wind can spread seeds that will grow new trees as tall as 6 feet their first year.

Ailanthus trees produce a lot of pollen and all parts of the tree can produce skin irritation in some individuals. If that doesn’t give you pause, we now have a new reason to double down on eliminating this invader: it is the preferred host tree for an exceedingly destructive insect, the spotted lanternfly (Lycorma delicatula), which may be making its way south! Removing Ailanthus now will make North Carolina less hospitable to this planthopper, which is a major pest of many fruits, including apples and grapes.

Adult Male Lanternfly

How to know if you have tree of heaven?

Characteristics to look for:

  • Bark: Smooth bark that looks somewhat like cantaloupe skin.
  • Leaves: Each leaf has from 10 to 40 leaflets with smooth edges, except for 1 to 2 “teeth” at the bottom of each leaflet. Leaves have a very strong peanut-butter odor.
  • Flowers: Yellowish flowers April through June.
  • Seeds: Winged seed pods in large clusters that may stay on the trees in winter.

Management
Tree of heaven is difficult to control because of its extensive root system and re-sprouting ability. Success depends on treatment timing and following up the next year. Be sure to wear gloves and other protective clothing when removing tree of heaven because of the possibility of allergic reactions.

Mechanical

  • Hand-pull young seedlings as soon as they are large enough to grasp. They are best pulled after a rain loosens the soil.
  • Remove the entire root because small root fragments are capable of generating new shoots.
  • Note that root suckers are easily confused with seedlings and are nearly impossible to pull by hand.
  • Although cutting down a tree of heaven will cause it to re-sprout and sucker, you may want to prune out limbs during the winter after leaf fall.
  • If seed clusters are present on cut limbs, collect, bag, and dispose of in heavy trash bags so they will not sprout have a chance to sprout.

Chemical

  • Herbicides containing the active ingredient triclopyr are effective. Apply all chemical treatments between July 1 and when the tree begins to show fall colors.
  • When removing a tree of heaven, use foliar herbicide sprays where tree height and distribution allow effective coverage without unacceptable contact with nearby desirable plants.
  • Treat the foliage with an herbicide first, allow 30 days for it to take effect before cutting the tree down.

 Native alternatives for Ailanthus altissima

Suggested by NCSU’s “Going Native” website:

  • Hickories (Carya)
  • Fringetree (Chionanthus virginicus)
  • Green Ash (Fraxinus pennsylvanica)
  • Smooth Sumac (Rhus glabra)

                              Article by Debbie Green, Extension Master GardenerSM Volunteer

 For more information:

Identifying:
https://projects.ncsu.edu/goingnative/howto/mapping/invexse/treeofhe.html

More on landscaping with native alternatives:
https://projects.ncsu.edu/goingnative/index.html

Spotted lanternfly watch:
https://ipm.ces.ncsu.edu/wp-content/uploads/2018/10/SpottedLanternflyPestWatch.pdf?fwd=no

 

Non-Native Invasive Plants: Chinese and Japanese Wisteria

Those looping vines of purple-lilac flowers that looked so attractive this spring? Probably non-native wisteria—and proof that you cannot always judge plants by their showy flowers! These vines are extremely invasive, infesting roadsides, forest edges, and rights-of-way. They grow up almost anything in their path—limited only by the height of whatever they climb, with stems reaching up to 15 inches in diameter! They can shade out tree leaves, decreasing photosynthesis, and eventually killing the tree.

Chinese Wisteria (Wisteria sinensis)

Wisteria identification
There are two Asian wisterias that have invaded most of the east coast and all of the southeastern United States: Japanese (Wisteria floribunda), which has lighter bark and twines counterclockwise around its host, and Chinese wisteria (W. sinensis) with dark gray bark that twines clockwise.

Management

Mechanical
For small wisteria infestations, remove entire plants, along with their roots and runners. Any root pieces left in the soil can re-sprout to produce new plants!

For more extensive infestations, cut climbing or trailing vines as close to the ground as possible. Although this may be labor intensive, it is a feasible control in areas where you cannot use herbicides. Cut vines back early in the season, and then every few weeks until the fall. This will stop growth of existing vines and prevent seed production. Remove wisteria vines from the bases of trees and shrubs to prevent girdling as the trees and shrubs grow.

Dispose of fruit, roots, and other plant parts in bags—not in the compost—to prevent re-infestation.

Chemical
The best time to apply an herbicide is in the spring and summer when wisteria is actively growing. Be sure to allow adequate time for the plant to regrow from the winter to ensure movement of the herbicide back into the underground portion.

Foliar application of a 2% (2.5 Ounces (oz) or 5 Tablespoons (Tbsp) per gallon of water) concentration of triclopyr with a 0.5% (0.5 oz or 1.25 Tbsp per gallon of water) nonionic surfactant is an effective control if you wish to use an herbicide. NOTE: If wisteria vines are growing up into trees or other desirable plants, you must pull the vines down prior to application of chemicals to minimize damage to the desirable vegetation. Do not cut the vines at ground level because the herbicide must move into the root system to provide better control!

If you must cut the vines at ground level, you can control the plants using the cut stump treatment method. Cut stems as close to the ground as possible and immediately apply a 25% (32 oz or 4 cups per gallon of water) solution of triclopyr to the stem. Wear disposable plastic gloves and se a disposable paint brush to apply the herbicide in order to ensure adequate coverage of the cut stem and minimize drift to desirable vegetation.

Native alternatives for Chinese and Japanese Wisteria
American Wisteria (Wisteria frutescens), native from Virginia to Missouri and south to Florida and Texas, is a clockwise twining deciduous woody vine that grows to 40 feet or more. It has fragrant, pea-like, lilac-purple flowers in drooping 6-inch long racemes that bloom in April-May after the leaves emerge but before they fully develop. This is an excellent vine for freestanding arbors, pergolas, posts, trellises, fences or terrace walls, but do NOT allow it to grow up desirable trees and shrubs!
Other native plant alternatives:
Hummingbird favorites:
• Coral honeysuckle (Lonicera sempervirens)

Coral Honeysuckle (Lonicera sempervirens)

• Crossvine (Bignonia capreolata)

Crossvine (Bignonia capreolata)

• Trumpet creeper (Campsis radicans)—this one can sucker and holds on with adhesive disks that can damage siding, so plant where it can spread away from your house!

Trumpet Creeper (Campsis radicans)

Butterfly host:
• Dutchman’s pipe (Aristolochia macrophylla)—Host plant for pipevine swallowtail butterflies

Dutchman’s Pipe (Aristolochia macrophylla)

Article by Bob Wardwell, Extension Master GardenerSM Volunteer
For more information:

Wisteria sinensis, Chinese Wisteria:
https://articles.extension.org/pages/62675/wisteria-sinensis-chinese-wisteria

Postemergence, Non-Selective Herbicides for Landscapes and Nurseries
https://content.ces.ncsu.edu/postemergence-non-selective-herbicides-for-landscapes-and-nurseries

As the vine twines:
http://www.namethatplant.net/article_asthevinetwines.shtml

Native vines for butterflies:
https://www.wildlifehc.org/10-native-vines-to-attract-butterflies/

 

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

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