Oriental bittersweet is a deciduous woody vine that can reach 19 m (60 ft) in height, and can grow to 10 cm (4 in) in diameter. Its leaves are simple and alternate. It blooms in May with small yellow-green flowers, and its numerous green berries turn red in yellow capsules upon maturity. Do not confuse Oriental bittersweet with the native, and relatively uncommon, American bittersweet (Celastrus scandens). The best way to tell the two species apart is that the flowers and fruits of female Oriental bittersweet are located in the leaf axils, but American bittersweet has only terminal flower clusters (both male and female).
Oriental bittersweet is a serious threat to plant communities due to its high reproductive rate, long-range dispersal, ability to root sucker, and rapid growth rate. Climbing vines severely damage or kill trees and shrubs by constricting and girdling stems, and by blocking sunlight. Oriental bittersweet has a wide range of habitat preferences including roadsides, thickets, young forests and dunes. It is shade tolerant, readily germinating and growing under a closed forest canopy. Seeds are dispersed readily by birds and small mammals.
Management Options:
A. Cutting:
Cut climbing or trailing vines as close to the root collar as possible. This technique is feasible on small populations; as a pretreatment on large impenetrable sites; and in areas where herbicide cannot be used. Cutting will reduce seed production and strangulation of surrounding woody vegetation. Oriental bittersweet will re-sprout unless cut so frequently that its root stock is exhausted. Treatment should begin early in the growing season and be repeated at 2-week intervals until autumn.
B. Grubbing:
This method is appropriate for small initial populations or environmentally sensitive areas where herbicides cannot be used. Using a “pulaski” or similar digging tool, remove the entire plant, including all roots and runners. Juvenile plants can be hand pulled depending on soil conditions and root development. Any portions of the root system not removed will potentially re-sprout. All plant parts, including mature fruit, should be bagged and disposed of in a trash dumpster to prevent reestablishment.
C. Herbicides:
Oriental bittersweet is fairly tolerant of glyphosate but is susceptible to triclopyr. Young vines or low-growing patches can be sprayed with triclopyr any time during active growth. Larger vines or vines that have climbed high into trees should be cut or girdled just above ground level in summer or early fall. Paint undiluted triclopyr into the freshly cut surfaces of the stump. Repeated applications may be necessary to eliminate re-sprouting.
BRUSH-B-GON [triclopyr (8%)]:
Foliar spray: 4 fl. oz./gal
Cut-stump treatment: Undiluted
References
Ahrens, J. F. 1987. Herbicides for control of oriental bittersweet. Proceedings, Northeastern Weed Sci. Soc. 41:167-170.
Dreyer, G. D. 1988. Efficacy of triclopyr in rootkilling oriental bittersweet (Celastrus orbiculatus Thunb.) and certain other woody weeds. Proceedings, Northeastern Weed Sci. Soc. 42:120-121.
Dreyer, G. D. 1994. Element Stewardship Abstract for Celastrus orbiculata (Oriental Bittersweet). The Nature Conservancy.
Mervosh, T. L. 1998. New England guide to chemical control of problem weeds and brush around homes and on non-cropland. Univ. of New Hampshire, Cooperative Extension. 7 p.
Tennessee Exotic Plant Management Manual, April 1997.