Plant Invaders of Mid-Atlantic Natural Areas: Vines
Kudzu was introduced into the United States from Japan in 1876 at the Philadelphia Centennial Exposition, where it was promoted as an ornamental and a forage crop plant. From 1935 to the mid-1950s, farmers in the South were encouraged to plant kudzu to reduce soil erosion, and the Civilian Conservation Corps planted it widely for many years. Kudzun nicknamed "the vine that ate the south," was eventually recognized as a pest weed by the U.S. Department of Agriculture and, in 1953, was removed from its list of permissible cover plants.
Distribution and Ecological Threat
Kudzu is common throughout most of the southeastern United States and in recent years has been found in northern states as well. It is apparently able to withstand harsher winter conditions than previously thought. Kudzu grows well under a wide range of conditions and in many soil types. Preferred habitats are open, sunny areas like forest edges, abandoned fields, roadsides and disturbed areas. Kudzu grows best where winters are mild, summer temperatures are above 80 degrees Fahrenheit and annual rainfall is 40 inches or more. Its vigorous growth and large leaves smother native plants; its vines kill trees through girdling and the added weight of vines can lead to uprooting trees. Once established, kudzu plants grow rapidly, extending as much as 60 feet per season, at the astonishing rate about 1 foot per day.
Description and Biology
- Plant: a climbing perennial vine in the pea family (Fabaceae); vines may extend 32 to 100 feet in length, with stems up to 4 inches in diameter. Roots are fleshy, with massive tap roots 7 inches or more in diameter, 6 feet or more in length, and weigh as much as 400 pounds; 30 vines may grow from a single root crown.
- Leaves: deciduous leaves are compound, with three broad leaflets up to 4 inches across; leaves alternate along stem; leaflets may be entire or lobed with hairy margins.
- Flowers, fruits and seeds: individual flowers, about 1/2 inch long, are purple, fragrant and borne in upright clusters during late summer. Fruits if present are brown, hairy, flattened seed pods, each of which may contain up to ten hard seeds.
- Spreads: mainly vegetative through expansion by runners and rhizomes and by vines that root at the nodes to form new plants; may spread by seeds in areas where a pollinator, the giant resin bee, occurs.
Jil Swearingen, NPS
Prevention and Control
For successful long-term control of kudzu, the extensive root system must be destroyed. Any remaining root crowns can lead to reinfestation of an area. Mechanical methods include cutting vines just above ground level, frequent mowing and cultivation. Use of systemic herbicides is the most effective and practical method currently employed. The federal government is investigating biological control agents for kudzu.
After eradicating, plant area with native vegetation appropriate to site conditions. Refer to References.
Publication by USFWS BayScapes Conservation Landscaping Program
Last updated: 7 October 2004