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Oriental Bittersweet: Weekly Wednesday

This week’s weekly Wednesday post is from council member, David Carmichael. David is a Landscape Technician with PEI’s Department of Agriculture and Forestry.

The images below are of Oriental Bittersweet (Celastris orbiculatis), which I came across while delivering upon a Forest Pest survey project for PEI. The site is located Eastern PEI and covers quite an extensive area.

Be sure to click the photos for a closer look and more information!

Management of Oriental Bittersweet:

Option 1: Regular cutting back of vines and not allowing regeneration or photosynthesis to occur for continued sustenance. Over a great period of time, if this practice is maintained, there may be a chance of eradication with gradual depletion of carbohydrate reserves. Note, often when vigorous plants are cut back, asexual reproduction is encouraged.

Option 2: Another option is chemical control. The PEIISC does not offer information on chemical control methods, however information is available on various websites. If chemical control is used, product labels should be strictly followed and considerations for possible environmental damage should be taken into account. Herbicide is prohibited around wetland environments in PEI.

Finally, avoid sharing plants with friends and be cautious of moving soils from areas populated with Oriental Bittersweet.

- David Carmichael, PEIISC Member and Landscape Technician with PEI’s Department of Agriculture and Forestry.

Oriental Bittersweet fruit and orientation on vines: Oriental Bittersweet flower and fruit positioning is axillary, meaning they originate from the leaf axils as opposed to the terminal or ends of the branch, indicative of the non-invasive North American species, Celastris scandens. (American Bittersweet) Plants are primarily polygamo-dioecious meaning plants are either male or female though some plants may have perfect flowers with the ability to reproduce as a single specimen. There are four modes of potential plant dispersal, plants have a capacity to produce high volumes of seeds that are spread by birds, plants also have great capacity to reproduce asexually by root suckering, plants can be shared between friends, or soils from infested areas may be inadvertently moved to non-infested sites.
Oriental Bittersweet fruit and orientation on vines: Oriental Bittersweet flower and fruit positioning is axillary, meaning they originate from the leaf axils as opposed to the terminal or ends of the branch, indicative of the non-invasive North American species, Celastris scandens. (American Bittersweet) Plants are primarily polygamo-dioecious meaning plants are either male or female though some plants may have perfect flowers with the ability to reproduce as a single specimen. There are four modes of potential plant dispersal, plants have a capacity to produce high volumes of seeds that are spread by birds, plants also have great capacity to reproduce asexually by root suckering, plants can be shared between friends, or soils from infested areas may be inadvertently moved to non-infested sites.
Open fruit of oriental bittersweet showing seeds within. Unfortunately, the vast majority of American Bittersweet is misidentified in the Ornamental Landscape trade. Unfortunately, Oriental Bittersweet may be widely distributed across the Island.
Open fruit of oriental bittersweet showing seeds within. Unfortunately, the vast majority of American Bittersweet is misidentified in the Ornamental Landscape trade. Unfortunately, Oriental Bittersweet may be widely distributed across the Island.
The twining and vigorous habit of this species is quite obvious. This species has the capacity to strangle many native and non-native trees and shrubs, often weighing them down to the point of collapse.
The twining and vigorous habit of this species is quite obvious. This species has the capacity to strangle many native and non-native trees and shrubs, often weighing them down to the point of collapse.
Second image of the vigorous habit of Oriental Bittersweet. The vigorous present-season growth can be seen in the foreground.
Second image of the vigorous habit of Oriental Bittersweet. The vigorous present-season growth can be seen in the foreground.