Celastrus orbiculatus (Oriental bittersweet)

This invasive deciduous woody vine was introduced to the United States from Southeast Asia in the 1860’s as an ornamental plant. Known for its prolific vining habit, and overwhelming seed production, this plant can be very difficult to manage. Oriental bittersweet is typically spread by animals, mainly birds and other animals that feed on the fruit as well as spreading by root suckers and stem layering.Oriental bittersweet can be found in forest edges, roadsides, meadows, and in other areas. Oriental bittersweet can establish itself quickly displacing other species. This plant can thrive in disturbed sites that result from flooding and storm events, as well as dense wooded areas. The loss of tree cover can lead to more sun in previously shaded areas, which in turn can lead to intensive spread of oriental bittersweet. Vines can girdle and constrict shrubs and trees leading to loss of ecological diversity in ecosystems.

Monitoring:

As for any invasive plant management plan, monitoring is a critical part of controlling this invasive plant. The leaves are alternate, rounded in shape and are broad with no point at the tip and dentate serrations. Flowers are generally non-descript but are green, and flower in small clusters at the leaf axils. The fruit is a very distinctive capsule that has an outer casing that is yellow with the seeds being bright red. This fruit is typically produced in the fall with maturation seen starting in August.

Control:

It is critical to establish early response to this invasive plant if possible! Manual removal can be done with young plants (hand-pulling), but if root fragments are left in the ground, it will come back with a vengeance. Window-cutting, the practice of cutting woody vines off of trees and shrubs by cutting a 3’ section of vine can be a great way of killing above ground portions of large bittersweet vine. This is best paired with a daub or cut-stump herbicide application with a systemic herbicide.

Herbicides are a critical part of IPM management of invasive species. Applications of herbicides as it relates to oriental bittersweet are typically applied in two ways:

1. Cut-stump application- cutting the vine at the ground and applying a systemic herbicide on the stump/stem left behind with a systemic herbicide is the best form of control. This minimizes off-target effects of herbicide and allows systemic movement of the herbicide to treat and kill the roots that can be difficult to manually remove. This method can be done any time of the year, however fall is generally the best time to conduct this herbicide application method due to the pulling of nutrients and plant sugars to the roots allowing herbicides to thoroughly infiltrate the root system.
2. Foliar- application of systemic herbicide onto the foliage of the plant; be extremely mindful of off-target drift effects when using this method of application as herbicides used to control oriental bittersweet are non-selective. Timing is critical if foliar applications are being made, as bittersweet leaves form a thick cuticle as the season progresses causing foliar herbicide application to become less effective. Therefore, the optimal time to treat bittersweet vines is generally spring into early summer as leaves emerge. A flush cut can be used to optimally treat oriental bittersweet foliage by cutting a vine and allowing it to resprout with young foliage that is more susceptible to herbicide application.

Herbicide product recommendations for oriental bittersweet can vary depending on the particular environment and goals of management. Generally glyphosate and triclopyr provide the best forms of control for oriental bittersweet. Always follow the label for pesticide applications and for specific recommendations, and reach out to your local Extension office for specific recommendations based on your situation.

Please keep in mind that for any of these treatment methods it will take multiple treatment cycles to get good control! There are no silver bullets in the control of tough invasive plants, but active and consistent management can lead to the reduction of invasive plant populations over time.

Resources:

NC State Extension- Invasive Plant Management: Forming a Game Plan After Helene

Plant Toolbox- Oriental Bittersweet

PennState Extension- Oriental Bittersweet