Wisteria sinensis

Photo credit: Nancy Dagley, USDI National Park Service, Bugwood.org

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Description

Chinese wisteria is a member of the Legume family (Fabaceae).
Chinese wisteria is a large, quick-growing woody vine prized in the horticultural trade for its’ attractive clusters of pendant purple flowers. (6)

Leaves
Leaves are alternate, compound, and contain 7-13 hairless leaflets. The species’ individual leaflets have wavy edges and long, pointed tips.

Flowers
Large clusters of pendant aromatic, purple flowers emerge in spring, usually in time with leaf-out. Clusters are large, generally 4-12 inches in length.

Fruit/Seed
Fruit is a velvety, elongate pod, 2-6 inches in length. Each pod contains 1-8 flat, round, brown seeds that are buoyant in water and are explosively propelled from the pod when ripe.

Introduction History

Grown around the world as a popular ornamental, Chinese wisteria was first introduced to the United States in the early 1800s. The species is now naturalized in 25 states and cultivated in all 6 temperate continents. (5)

Ecology and Habitat

Commonly found at old homesites or close to intentionally planted populations, Chinese wisteria does not yet appear to spread easily or rapidly in natural areas in New York. This may be because the species’ main method of reproduction is vegetative, and seed distribution remains highly localized. The species is tolerant of a wide range of soils, particularly freely draining, dry soils and has the potential to colonize a wide variety of habitats. (5)

Reproduction and Phenology

Chinese wisteria primarily reproduces vegetatively, via stolon production and rooting. Although seeds are viable, large, heavy seeds and seed pods limit movement from the original population by birds or mammals. Seeds can be moved great distances by water, however. Seedlings take upwards of twenty years to mature and, once established, can live for a hundred years or more. (2) The hybrid between Japanese wisteria and Chinese wisteria (Wisteria x formosa) may be more vigorous and widespread than either of the two species individually. (3) Vectors include water and horticultural trade.

Impacts of this species

Chinese wisteria is a woody, perennial liana native to China. Vines spread by ground runners, covering the ground and twining around other vegetation to climb into the canopy. Dense foliage can smother, girdle and outcompete other vegetation, even killing sizeable trees. The resulting canopy gaps are excellent colonization sites for new invasive species.

Management Methods

Biological Control
No information available

Manual or Mechanical Control
Pulling / Digging Up: Pulling as a control method is possible only if plants are very young. Once wisteria becomes woody it is very difficult to remove by physical means. Any root fragments left in soil have the potential to re-sprout. (5)

Mowing: Chinese wisteria sprouts from cut stumps and low growing stolons may escape mower blades and continue to spread. If performing this method of management, cutting or mowing must be repeated every 2-3 weeks throughout the growing season. (3)

Girdling: Not applicable

Prescribed Fire: No information available

Prescribed Grazing: Wisteria is known to be toxic to certain grazing animals. (5)

Soil Tilling: Given Chinese wisterias ability to regenerate from root fragments, this method of control is inadvisable. (3)

Mulching: Not applicable

Solarization: Not applicable

Hot Foam Spray: No information available

Chemical Control
The pesticide application rates and usage herein are recommendations based on research and interviews with land managers. When considering the use of pesticides, it is your responsibility to fully understand the laws, regulations and best practices required to apply pesticides in a responsible manner. At times, the pest you seek to treat may not be on a pesticide label, requiring a 2ee exemption from NYSDEC. Always thoroughly read the label of any pesticide and consult the NYSDEC or a licensed pesticide applicator with questions.

Foliar Spray: High rates and repeat applications of foliar spray are necessary to come close to eradication of Chinese wisteria populations. Application is most effective in warmer temperatures and should be performed from June-September. A follow up application is advisable 3-6 weeks after initial treatment. This method of management should be performed only in areas where the much more effective cut-stump methods would be impractical. Always read and follow all instructions on the herbicide label. (3)

Cut Stump: Cut stump herbicide application is an effective way of managing Chinese wisteria, however, high rates of chemical application must be employed (25% solution of glyphosate or triclopyr in water). Furthermore, this method can only efficiently be used on larger vines with a greater surface area. Treatment should be performed during the latter half of the growing season and repeat treatment may be necessary to kill root sprouts. (4)

Basal Bark: Treat with a 15-30% solution of triclopyr in oil. (7)

Stem Injection: Not applicable

Pre-Emergent Spray: Not applicable

Summary of Best Managment Practices

General management overview and recommendation
The most efficient method of management will depend upon the size and age of the target population. In most cases, a several pronged approach, marrying hand pulling of young plants with foliar spray and cut stump treatment of larger plants will be necessary.

Post treatment monitoring
Controlled populations should be revisited every 2-3 weeks after management to monitor for re-growth. Expect to retreat managed populations yearly if eventual eradication is the goal.

Disposal Methods
Stolons and root fragments are able to re-sprout: all material must be thoroughly dried, chipped, burned, or disposed of in a landfill.

Additional Information

REFERENCES

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