November Weed of the Month: Oriental Bittersweet

Having trouble viewing this email? View it as a Web page.

department of agriculture


Tuesday, November 7, 2017

November Weed of the Month: Oriental Bittersweet

Emilie Justen, Minnesota Department of Agriculture

November’s Weed of the Month, Oriental bittersweet (Celastrus orbiculatus), is a woody vine with colorful red fruit. It was brought to North America from the Asia and used as an ornamental plant. The attractive vines have been used for wreath decorations and in floral decorations; unfortunately, the plant has escaped cultivation and has become invasive in residential and natural areas in Minnesota.

Oriental bittersweet spreads by several means. The persistent red fruit is consumed by birds, which spread the seed to uninfested areas. People trained to look for Oriental bittersweet may look for places where birds perch. The areas beneath the perches may have Oriental bittersweet seedlings, juvenile vines, or mature woody vines and would be a place to target control efforts. Humans also spread Oriental bittersweet infestations by physically moving the plants. Oriental bittersweet was commonly propagated and sold in Minnesota through nurseries and retail garden centers before 2010. Its use in floral arrangements and wreaths also increased its spread.

Despite its ornamental characteristics, Oriental bittersweet is an ecological threat to forests, grasslands, and parks in Minnesota. The vines twine around trees, girdling them in a snake-like fashion. Though it prefers forest edges and sunlight, Oriental bittersweet can grow in forest understories, eventually reaching forest canopies, shading the trees and understory and preventing native plant species from flourishing. Infestations can become so thick that wildlife, such as deer, can have difficulty navigating through wooded areas filled with Oriental bittersweet.

Oriental bittersweet has identification characteristics to help distinguish it from other woody vines. The mature fruit is a red berry with a yellow capsule. The berries are attached along the stem where the leaves meet the stem. This should not be confused by American bittersweet which has red berries with orange capsules. Additionally, dense infestations of Oriental bittersweet will give a wooded area a messy, chaotic look.

As a target weed on Minnesota’s Noxious Weed Eradicate List, it’s required by law that all above- and below-ground plant parts must be destroyed. Recommended management practices for Oriental bittersweet include the following:

  • Do not collect and use the fruiting stems for ornamental purposes. Do not plant Oriental bittersweet or propagate any of its plant parts.
  • Foliar or cut stump herbicide applications can be effective. For specific herbicide recommendations, contact a University of Minnesota Regional Extension Educator.
  • All management practices for Oriental bittersweet should include monitoring and treating repeatedly until the seedbank is depleted.

To report infestations of Oriental bittersweet or any other noxious weeds on the eradicate list, please notify the MDA by email at arrest.the.pest@state.mn.us, or voicemail at 1-888-545-6684 (toll-free).

PHOTO ATTACHED: Fruit of Oriental bittersweet has a red berry with a yellow capsule and is located along the stem.

Caption: Fruit of Oriental bittersweet has a red berry with a yellow capsule and is located along the stem.

MEDIA: For more information on Weed of the Month, contact Allen Sommerfeld, MDA Communications, at allen.sommerfeld@state.mn.us or 651-201-6185.