SLELO PRISM

Oriental Bittersweet

Oriental bittersweet (Celastrus orbiculatus) is a deciduous woody perennial vine that is native to eastern Asia.  It is in the stafftree family and may reach 66 ft in length.    

Impacts

Oriental bittersweet invades a great variety of sites including thickets, forests, beaches, roadsides, old fields, and urban areas.  It outcompetes trees, shrubs, and other vegetation through climbing and shading.  It may also kill trees by girdling them.  The seeds are dispersed by water, humans, and animals.  Birds and small mammals are attracted to the red inner portion of the fruit and spread the seed after ingesting. 

Habitat

Oriental bittersweet can grow in many different soil types and tolerates a range of soil moistures.  It is shade and sun tolerant and can survive and grow slowly in closed-canopy forests until sunlight through disturbance becomes available.         

Identification  

Stems: Occasionally branching, twining, and up to 4 in. wide. 

Leaves:  Alternate, light green in color (turn yellow in fall), oblong to elliptical shaped (highly variable), 2-5 inches long and 1.4-2.0 inches wide with round, fine toothed margins and a tip that comes to an abrupt sharp point or short taper to a point. 

Flowers:  Small greenish yellow flowers with 5 petals that are clustered in leaf axils from May-June. 

Fruit:  Occurs from July to October.  Starts out green in color then turns yellow late in summer with outer layer splitting into 3 parts revealing bright red fruit inside. 

Lookalike:  American bittersweet (Celastrus scandens) is native and looks very similar to Oriental bittersweet.  It has more elliptical leaves (twice as long as they are wide), while oriental bittersweet is usually more oval (less than twice as long as wide).  This difference must be observed with caution since oriental bittersweet leaves are highly variable.  A definitive difference is that oriental bittersweet flowers/fruit are clustered in the leaf axils, while American bittersweet are clustered at the end of the stems.  Also, the husk of Oriental bittersweet fruit is yellow, rather than orange.

Management: 

Successful management strategies may require a multi-year effort. Always follow chemical label instructions. 

Hand-pulling: This method requires the removal of the entire plant including the roots and should be only used for small patches. All climbing vines should be first cut at a comfortable height prior to the removal of roots. DAmage to host tree should be minimized. Plants bearing fruit should be burned or bagged and disposed of in a landfill. Repeat pulling will likely be required since re-sprouting will occur without chemical treatment. 

Cut stem treatment: Stems should be cut about 2inches above the ground and followed immediately by application of 25% glyphosate or triclopyr solution to the cut stem. 

Basal bark treatment: Use a string trimmer or hand saw to remove some of the foliage in a band a few feet from the ground. Apply 20% solution of triclopyr ester in commercially available basal oil with a penetrant to vine stems. Avoid getting herbicide on the host tree.

Foliar treatment: This method should be used for large patches of Oriental bittersweet. Apply either 2% solution of triclopyr ester or triclopyr amine mixed in water with a  non-ionic surfactant to the leaves. Thoroughly wet the foliage with herbicide, but not to the point of runoff. 

Resources: 

Mistaken Identity: Invasive Plants and Their Native Look-alikes 

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Prevent the introduction of invasive species into the SLELO PRISM.

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Control invasive species infestations by using best management practices, methods and techniques to include: ERADICATION (which is to eliminate all individuals and the seed bank from an area), CONTAINMENT (which is reducing the spread of established infestations from entering an uninfested area) and SUPPRESSION which is to reduce the density but not necessarily the total infested area.

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Rob Williams
PRISM Coordinator

Megan Pistolese
Outreach and Education

Brittney Rogers
Aquatic Invasive Species

Robert Smith
Terrestrial Invasive Species

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