Wisteria spp
From BugwoodWiki
Authors: Tunyalee Martin, Global Invasive Species Team, The Nature Conservancy
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Identifiers
Latin Names:
Wisteria sinensis Sims (DC)
Wisteria floribunda (Willd.) DC.
Common Names:
Chinense wisteria, Japanese wisteria
Wisteria sinensis, in the Fabaceae, is a perennial vine commonly called Chinese wisteria. Wisteria floribunda is called Japanese wisteria.
Stewardship summary
Chinese wisteria was introduced into the U.S. from China in 1816 as an ornamental. This invasive vine can be found throughout the eastern U.S., south of (and including) TX, AR, MS, IL, KY, WV, PA, NY, VT, and MA, and it has also been reported as far north as MI (Anonymous 2002a).
Natural history
General description
Although still used in horticulture, Chinese wisteria can harm wildland species by twining around native shrubs and trees, and shading out light. The death of large trees results in breaks in closed canopies, which favors further growth of wisteria. Japanese wisteria (Wisteria floribunda) is similar to Chinese wisteria, and was introduced in 1830. It is also widely used in horticulture.
Chinese wisteria and Japanese wisteria both overtake natives and grow in dense thickets, excluding all other plants (Johnson 2002). Both species have pods and seeds that are toxic if ingested causing such symptoms as nausea, vomiting, stomach pains and diarrhea (Anonymous 2002b).
The leaves of Chinese wisteria and Japanese wisteria are alternate and pinnately compound. Leaves are up to 30 cm in length with 7-13 leaflets (Chinese wisteria) or 13-19 leaflets (Japanese wisteria). The fragrant flowers of Chinese wisteria are 1.27 – 2.5 cm in length and are usually blue-violet in color. However, cultivars with white, purple, pink, and lavender flowers exist, and these flower colors may occur in escaped plants. Japanese wisteria has a similar range of flower colors. The flowers of both species are usually produced April to May and hang in clusters that can exceed 40 cm in length. The seedpods are large (10- 15 cm), hairy and brown in color. They narrow at the bases and have constrictions between the seeds. Japanese wisteria has white-bark and the vines encircle the host plant clockwise (as viewed from above), while Chinese wisteria twines in opposite direction.
Vines of wisteria can live for 50 years or longer and grow to a diameter of 38 cm. Although seeds are produced in favorable conditions, vegetative growth is the main method of wisteria spread. Rivers can carry seeds downstream to further the spread of this invasive vine (Johnson 2002).
Similar Native Species
Native American wisteria, Wisteria frutescens, occurs in the eastern and southeastern U.S. (all states east and south of IL, IA, MS, OK, TX; except VT, NH, ME). However, American wisteria produces its purplish to white flowers later in the year (June – August) and has smaller (5-10 cm), non-hairy seedpods (Johnson 2002).
Habitat
Both wisteria species grow best in full sun but are shade-tolerant. These hardy vines are found in a variety of soil and moisture conditions, preferring loamy, well-drained soils. They typically infest forest edges and disturbed areas, such as roadsides, ditches, and rights-of-way (Johnson 2002).
Management/Monitoring
Careful horticulture
Alternate plants that should be recommended by horticulturalists or native plant societies (Johnson 2002) instead of Chinese or Japanese wisteria are:
American wisteria (Wisteria frutescens) – found throughout the east – TX, OK, MO, IA, MI plus states eastward except VT, NH, and ME.
Trumpet creeper (Campsis radicans) – found in UT and CO and in states east of (and including) TX, OK, KS, NE, SD and ND, except MN, VT and ME.
Trumpet honeysuckle (Lonicera sempervirens) – found in and the states east of TX, OK, KS, IA and MI, except IN.
Dutchman’s pipe/pipevine (Aristolochia macrophylla) – found in MI and in states east of (including) AL, TN, KY, WV, PA and New York, except FL, ME, NH, RI and DE.
Crossvine (Bignonia capreolata) – found in the SE states bordered by TX, OK, MO, IL, IN, OH, WV and MD.
Mechanical Control
Mechanical control methods can be labor intensive and are usually better suited for small populations. However, these methods are best for sensitive areas where herbicides could damage desirable species (Johnson 2002) and if trampling damage can be kept to a minimum.
Cut vines close to the root collar to discontinue growth of existing vines, reduce seed production, and eventually exhaust the photosynthates stored in the root. Wisteria will resprout; repeated cuttings every 2 weeks are recommended from early in the growing season until autumn. Remove cut vines, or cut vines into smaller lengths because they may continue to grow and girdle trees and shrubs (Johnson 2002).
Remove entire plants and roots using a pulaski, weed wrench, or other tools. Try to remove the entire plant as any plant parts left can resprout. Bag and dispose (Johnson 2002).
Chemical Control
Use cut-stump herbicide applications in areas with large stands of established vines or where desirable plants occur that could be affected by a foliar spray. Cut the vine close to the ground and apply glyphosate or triclopyr (25% solutions in water) to the cut area. Retreatment may be necessary if resprouting occurs. These treatments are not effective if the ground is frozen (Johnson 2002).
Use foliar sprays in areas where mechanical control methods would be disruptive, or where cut-stump methods are impractical. Compared to cut-stump applications, the use of foliar sprays requires additional precautions because non-target plants have a greater likelihood of being affected. Spray the foliage thoroughly, but do not apply so much herbicide that it drips off the leaves. Since translocation is slower during cooler weather, the foliar application may be more effective at warmer temperatures (above 60- 65°F). Triclopyr (2% with 0.5% non-ionic surfactant) is specific for the control of broadleaved plants – as such, it may be particularly appropriate in situations where valuable native grasses are near the wisteria plants to be treated. Glyphosate (2% solution with 0.5% non-ionic surfactant) is non-selective. Chlopyralid (0.5% solution) targets aster, buckwheat, and the pea family. However, chlopyralid can leach into groundwater in sandy and limestone soil types (Johnson 2002). Picloram (4.731 L/ha or 0.5 gal/acre with 0.5% non-ionic surfactant) may provide control in areas where desirable vegetation is not present (Byrd 2002)
Information sources
Bibliography
Anonymous 2002a. http://plants.usda.gov, accessed 2002.
Anonymous 2002b. http://chppm-www.apgea.army.mil/ento/PLNTORNA.HTM, accessed 2002.
Byrd, J. 2002. Professor/Extension Specialist, Department of Plant and Soil Sciences, Mississippi State University, personnal communication.
Johnson, K. 2002. Great Smoky Mountains National Park, Gatlinburg, TN (kris_johnson@nps.gov) and Tennessee Exotic Plant Pest Manual for Japanese wisteria, http://www.nps.gov/plants/alien/fact/wist1.htm, accessed 2002.
