Wednesday, December 18, 2013

Learn to Identify Oriental Bittersweet

Oriental bittersweet can cause severe tree damage.  It is
easily identified in the fall by its yellow foliage.
Oriental bittersweet (Celastrus orbiculatus) is an invasive exotic vine that is often used in holiday decorations and wreaths this time of year.  It also causes severe damage to our woodlands as it climbs trees and shrubs strangling and shading them out.  It can cause severe tree damage.  I have experienced this vine first-hand at the Ag Progress Days woodlot in central PA.  I found one severe infestation of the vine in an old patch clearcut from 15 years ago and now I have been finding the vine everywhere.

Oriental bittersweet is often used
for making wreaths this time of year

It is extremely difficult to control.  I have been trying to rid the woodlot of the vine since I discovered it a few years ago and I just keep finding more.  I have also found that not only does the vine climb trees but it also root sucker and send up sprouts.  Theses new sprouts are extremely difficult to find and control.  I have spent hours searching through areas with a backpack sprayer treating new sprouts.  When spraying I use a mixture of glyphosate and triclopyr mixed 2:1 respectively.  This mix is also good for other invasive plants you may encounter and want to treat at the same time.

It is important that you learn to identify Oriental bittersweet as we also have a native American bittersweet (Celastrus scandens).  The two are often confused and unfortunately, they are know to hybridize.  The University of Minnesota Extension has put together and excellent YouTube Video on how to easily identify the invasive exotic vine and differentiate it from the American vine.  Now is a great time to watch for it and avoid spreading the seeds. Minnesota's new Extension fact sheet will also help you differentiate between native American bittersweet and its noxious invasive cousin.
Oriental bittersweet has yellow seed capsules and the fruits are located
all along the stem in the axils of the leaf
The primary ways to differentiate between the two are as follows:
American Bittersweet
Flowers and fruits are at the ends of the branches
Seed capsules are orange

Oriental Bittersweet
Flowers and fruits are in the axils of the leaves all along the vine
Seed capsules are yellow

Here is the link to the PA DCNR Invasive Plants of Pennsylvania fact sheet on Oriental Bittersweet.

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