Its seems that wisteria is everywhere I look. I see it intertwined in trees, in abandoned lots, along fences, in the woods, and in some landscapes planted on purpose. I will admit that the flowers are beautiful, but this plant can have deadly consequences on mature trees.
Wisteria is found from Maine to Florida, and as far west as Arkansas. There are native, W. frutescens, and non-native types of wisteria, including Japanese wisteria (W. floribunda) and Chinese wisteria (W. sinensis). Wisteria is sold in garden centers and nurseries and can be found in numerous home gardens across the country. The problem with wisteria lies in its growth habit. Wisteria is a vine that will grow virtually up anything in its path. By climbing into the canopy of trees or plants, it can shade them out, impairing those plants from effectively growing. Over time, wisteria will climb and twine around other plants, eventually shading and girdling native plants
Mechanical methods are commonly used for wisteria management. For small wisteria infestations, cut climbing or trailing vines as close to the root as possible. Although this may be labor intensive it is a feasible pretreatment for larger infestations or in areas where herbicides cannot be used. Because wisteria will continue to sprout after it has been cut, it should be cut back early in the season, cutting sprouts every few weeks until the fall. This will stop growth of existing vines and prevent seed production. Wisteria vines should be removed from bases of trees and shrubs to prevent girdling as the trees and shrubs grow.
Another control tactic for small infestations is the removal of entire plants. Any type of digging tool can be used to remove the entire plant (roots and runners). It is important to know that any root pieces remaining in the soil may resprout to produce new plants. Fruit, roots, and other plant parts should be disposed of properly to prevent reinfestation.
In areas with established wisteria, a cut stump treatment is effective. Cut stems as close to the ground as possible and immediately apply a 25% solution of glyphosate or triclopyr to the stem. A foliar application of glyphosate may be necessary for sprouts. For larger infestations of wisteria foliar herbicide applications may be necessary. To avoid damaging nontarget species, stump treatments should be administered before foliar treatments. A solution of water and a 2% concentration of glyphosate or triclopyr with a 0.5% nonionic surfactant should be applied. If wisteria vines are growing up into trees or other desirable species, vines should be cut or pulled down to minimize damage to the desirable vegetation. Pulling the vines down without severing them from the underground rootstocks will allow the herbicide to move into the root and provide better control. The best time to apply an herbicide is in the spring and summer when wisteria is actively growing. Be sure to allow adequate time for the plant to regrow from the winter to ensure movement of the herbicide back into the underground portion. (As plants grow and mature, they begin to move sugars back into the roots).
Photos by James Morgan
Plant. Deciduous high climbing, twining, or trailing leguminous woody vines (or cultured as shrubs) to 70 feet (20 m) long. Chinese and Japanese wisteria difficult to distinguish due to possible hybridization.
Stem. Woody vines to 10 inches (25 cm) in diameter with infrequent alternate branching. Twigs densely short hairy. Older bark of Chinese wisteria tight and dark gray with light dots (lenticels) compared to white bark of Japanese wisteria.
Leaves. Alternate, odd pinnately compound 4 to 16 inches (10 to 40 cm) long, with 7 to 13 leaflets (Chinese) or 13 to 19 leaflets (Japanese), and stalks with swollen bases. Leaflets oval to elliptic with tapering pointed tips 1.6 to 3 inches (4 to 8 cm) long and 1 to 1.4 inches (2.5 to 3.5 cm) wide. Hairless to short hairy at maturity but densely silky hairy when young. Margins entire and wavy. Sessile or short petioled.
Flowers. March to May. Dangling and showy, stalked clusters (racemes) appearing when leaves emerge, 4 to 20 inches (10 to 50 cm) long and 3 to 3.5 inches (7 to 9 cm) wide. All blooming at about the same time (Chinese) or gradually from base (Japanese). Pealike flowers, corolla lavender to violet (to pink to white). Fragrant.
Sources: Nonnative Invasive Plants of Southern Forest and University of Florida Center for Aquatic and Invasive Plants Wisteria sinensis