Managing Oriental Bittersweet

Oriental bittersweet fruit allows easy recognition in fall

Oriental bittersweet (Celastrus orbiculatus) is an introduced plant from Asia that was brought here primarily for reducing soil erosion and its fall display of colorful fruit.  It is the fruit that allows easy recognition in fall. It has become an invasive species in more than half of the eastern US.  It is a vining-type plant that can grow up and over herbaceous and woody plant material and cause their decline and die-back through shading. Vines, as they wrap around woody trees and shrubs can girdle branches and trunks causing die-back.  Trees overgrown with bittersweet become more susceptible to wind damage (breakage and uprooting) due to the extra weight on trees.  It is displacing our native bittersweet (Celastrus scandens) through over competing and hybridizing.

Oriental bittersweet produces fruit at leaf axils along stem

The 2 species can be differentiated when in fruit as American bittersweet only has fruit at the ends of growth whereas Oriental bittersweet bears fruit along its stems.  Oriental bittersweet has alternate branching, finely serrated leaf margins with leaves around 2-5” long, reddish-brown stems when young that turn gray with lenticels as they age and yellow fruit capsules that break open to reveal to orange to red arils that contain seed.

Oriental bittersweet spreads by both seeds eaten and dropped by birds and vegetatively via root suckering. Seed can remain viable for several years in soils. Plants tend to be dioecious (male and female plants). Control requires either 1) pulling of plants/vines as cut vines will re-sprout (keep in mind that if a section of root breaks off the remaining section may re-sprout) 2) cutting larger vines near the ground and treating the cut surface with a systemic herbicide like Roundup or 3) spraying of smaller plants or plants that have been cut back over the foliage from mid-summer to fall. The key to managing oriental bittersweet, like any invasive, is preventing seed production.

Recognition of young plants aids control

Existing vines/plants will require eradication by physical or chemical means. It will take a minimum of a few years (or more depending on size of area) for the existing seed in soils to sprout to get a problem under control assuming fruit production is halted.