Kudzu (Pueraria montana)
September 11, 2007
Kudzu is a deciduous twining, trailing, mat-forming, woody leguminous vine 35 to 100 feet with lobed three-leaflet leaves. Read more about the "vine that ate the South" and how to control it.
Plant. Deciduous twining, trailing, mat-forming, ropelike woody leguminous vine, 35 to 100 feet (10 to 30 m) long with three-leaflet leaves. Large semiwoody tuberous roots reaching depths of 3 to 16 feet (1 to 5 m). Leaves and small vines dying with first frost and matted dead leaves persistent during winter.
Stem. Woody vines to 10 inches (25 cm) in diameter, round in cross section, with infrequent branching. Stems yellow green with dense erect golden hairs and upward matted silver hairs, aging to ropelike, light gray, and hairless. Frequent unswollen nodes that root when on the ground. Mature bark eventually rough, rigid, and usually dark brown.
Leaves. Alternate, pinnately compound three-leaflet leaves, each leaflet 3 to 7 inches (8 to 18 cm) long and 2.5 to 8 inches (6 to 20 cm) wide. Usually slightly lobed (unless in shade): a two-lobed symmetric middle leaflet and two one-lobed side leaflets, all petioles swollen near leaflets. Tips pointed. Margins thin membranous and fine golden hairy. Leafstalks 6 to 12 inches (15 to 30 cm) long, long hairy, base swollen, with deciduous stipules.
Flowers. June to September. Axillary slender clusters (racemes), 2 to 12 inches (5 to 30 cm) long, of pealike flowers in pairs (or threes) from raised nodes spiraling up the stalk, opening from the base to top. Petals lavender to wine colored with yellow centers.
Fruit and seeds. September to January. Clustered dry, flattened legume pods (bulging above the seeds) each 1.2 to 3 inches (3 to 8 cm) long and 0.3 to 0.5 inch (8 to 12 mm) wide. Green ripening to tan with stiff golden-brown hairs. Splitting on one to two sides to release a few ovoid seeds.
Ecology. Occurs in old infestations, along right-of-ways and stream banks. Forms dense mats over the ground, debris, shrubs, and mature trees forming dense patches by twining on objects less than 4 inches (10 cm) in diameter. Colonizes by vines rooting at nodes and spreads by wind-, animal-, and water-dispersed seeds. Seed viability variable. Leguminous nitrogen fixer.
History and use. Introduced from Japan and China in early 1900s with continued seed importation. Erosion control, livestock feed, and folk art.
Recommended control procedures: Thoroughly wet all leaves (until runoff) with one of the following herbicides in water with a surfactant:
July to October for successive years when regrowth appearsÂTordon 101* Â as a 3-percent solution (12 ounces per 3-gallon mix) or Tordon K* Â as a 2-percent solution (8 ounces per 3-gallon mix), either by broadcast or spot sprayÂspraying climbing vines as high as possible.
July to September for successive yearsÂEscort* XP at 3 to 4 ounces per acre in water (0.8 to 1.2 dry ounces per 3-gallon mix)Âor when safety to surrounding vegetation is desired, TranslineÂ as a 0.5-percent solution in water (2 ounces per 3-gallon mix); spray climbing vines as high as possible or cut vines that are not controlled after herbicide treatment.
For partial control, repeatedly apply Garlon 4 or a glyphosate herbicide as a 4-percent solution in water (1 pint per 3-gallon mix) with a surfactant during the growing season. Cut large vines and immediately apply these herbicides to the cut surfaces. Or, apply Garlon 4 as a 20-percent solution in basal oil, vegetable oil, crop oil concentrate, diesel fuel, or kerosene (2.5 quarts per 3-gallon mix) or apply undiluted Pathfinder II as a basal spray to large vines as a basal spray (January to April), which controls vines less than 2 inches in diameter. * Nontarget plants may be killed or injured by root uptake. Â Transline controls a narrow spectrum of plant species. Â When using Tordon herbicides, rainfall must occur within 6 days after application for needed soil activation. Tordon herbicides are Restricted Use Pesticides.
From: Miller, James H. 2003. Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS-62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 p.
Read more about kudzu and other invasive plants in the Spring 2005 issue of Compass magazine at http://www.srs.fs.usda.gov/compass/spring2005/