Kudzu

Kudzu [Pueraria montana (Lour.) Merr.], often called “the vine that ate the South,” is a perennial, high-climbing vine native to eastern India, China, and Japan. It was introduced into the United States in 1876 at the Centennial Exposition in Philadelphia, Pennsylvania, and was recognized as highly nutritious livestock forage in 1905. By 1946, an estimated 300,000 acres were planted. In addition to its use as forage, kudzu was also widely planted for soil stabilization in the South. It has also been used as an ornamental and for certain edible and medicinal uses.

It is a noxious weed in Florida, Illinois, Kansas, Kentucky, Mississippi, Missouri, Pennsylvania, Texas, and West Virginia. It can be problematic in all southeastern states and in almost all habitats except aquatic. Kudzu can host Asian soybean rust, a potentially serious pathogen in soybeans [Glycine max (L.) Merr.]

Description

Vegetative Growth

The genus Pueraria belongs to the Pea (Fabaceae or Leguminosae) family. Of the 17 Pueraria species native to the tropics and East Asia, only two grow in the United States—P. phaseoloides (Roxb.) Benth. and P. montana. Of the two species, only P. montana var. lobata (Willd.) Maesen and S. almeida (kudzu) are problems in the continental U.S.

A perennial, kudzu is a semi-woody, trailing to high-climbing, twining vine that reaches around 80 feet in length. Trailing stems may root when in contact with the soil and produce large, tuberous roots, which are edible and sometimes eaten in Asian countries. Twining generally occurs around objects less than 4 inches in diameter. Stems are covered with stiff, rust or golden hairs when young and, as they grow, turn brown, semi-woody, and smooth. Stems can grow up to 10 inches in diameter. Leaves are alternate and trifoliolately compound (Figure 3) with leaflets 2–8 inches long. Leaves are covered with hairs and typically lobed (Figure 3). Petioles are 6–12 inches long with swollen bases and deciduous, ovate-lanceolate stipules.

Flowering

Kudzu flowers August through September. Flower panicles are axillary, 2–12 inches long, and open from bottom to top (Figure 1). Flowers are about 1 inch in diameter and occur in twos or threes in a spiral pattern up the main axis. Lower petals are lavender or violet-purple, and upper petals are similar in color or pinkish with a yellow patch near the base. Flowers are fragrant to attract pollinators. Clustered fruit are produced from September to January. They are flattened legumes (or pods) 1.2–3 inches long, 0.3-0.5 inches wide, and covered with stiff, golden-brown hairs, very similar in appearance to soybean pods. Seeds are egg-shaped to nearly square and are around 0.1 inches in diameter. Seed viability is variable but generally very poor.

Dispersal

Kudzu spreads primarily by rooting at nodes along stems in contact with soil.

Habitat

Kudzu is problematic in all habitats except aquatic. It forms dense thickets, quickly shading out trees and vegetation. It is relatively drought tolerant and will grow in a wide range of soils. Once established, kudzu is difficult to eradicate.

Distribution

Kudzu is widespread throughout the Midsouth, particularly on slopes. Kudzu normally occurs from Maine to Florida and as far west as Nebraska and Texas. It has also escaped in Washington and Oregon. In 2009, kudzu was found near Ontario, Canada.

Control Methods

Mechanical

Some mechanical methods of kudzu control may be used in areas that can be grazed, mowed, or tilled. Mechanical controls, including hand removal, can be successful for small infestations, but the root must be removed from the soil. Because stems can propagate through fragmentation, be careful to remove all stems.

Chemical

See Table 1 for recommended herbicides for kudzu control. Metsulfuron can be applied over pines, but it should not be applied on foliage of desirable vegetation. Imazapyr, picloram, aminocyclopyrachlor, aminopyralid, and clopyralid can be absorbed by roots and damage desirable trees and other broadleaf plants. Do not apply within two times the dripline to avoid injury. Clopyralid can be applied over certain hardwood; see labels for lists of tolerant species. Nonionic surfactant should be added with foliar applications.

Biological

Livestock readily graze kudzu. Continuous grazing may result in stand loss.

References

Langeland, K. A., & Craddock Burks, K. (Eds). (1998). Identification and biology of nonnative plants in Florida’s natural areas. University of Florida.

Miller, J. H. (2003). Nonnative invasive plants of southern forests: A field guide for identification and control. Gen. Tech. Rep. SRS-62. U.S. Department of Agriculture, Forest Service, Southern Research Station.

United States Department of Agriculture. (1948). Grass: The yearbook of agriculture 1948. United States Government Printing Office.

USDA, Natural Resources Conservation Service. (2018). The PLANTS database. National Plant Data Team.

Publication 3187 (POD-04-24)

By John D. Byrd Jr., PhD, Extension/Research Professor, Plant and Soil Sciences; Victor Maddox, PhD, Senior Research Associate, Plant and Soil Sciences; and Randy Westbrooks, PhD, former Invasive Species Specialist, U.S. Geological Survey.