Bill Johnson

Kudzu

Pueraria montana var. lobata (Willd.) Maes. & S. Almeida
Pea family (Fabaceae)

Origin: Temperate and Tropical Asia, Australasia, and Pacific

Background
Kudzu was introduced to the United States from Japan in 1876 at the Philadelphia Centennial Exposition, as an ornamental plant. In early 1900s, it was recognized and promoted as a forage crop and planted throughout the southeastern U.S. In the 1930s and 1940s, the Soil Conservation Service paid southern farmers to plant kudzu to reduce soil erosion on deforested lands, resulting in over 1 million acres being planted. Kudzu, nicknamed “the vine that ate the South,” was recognized as a pest weed in the 1950s and removed from the list of acceptable species in the Agricultural Conservation Program. In 1998, it was listed as a federal noxious weed by the U.S. Congress.

Distribution and Habitat
Kudzu occurs primarily in the eastern U.S. and has been reported to be invasive in natural areas from Connecticut to Florida and west to Texas. Infestations have also been reported in North Dakota and Oregon. 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°F and annual rainfall is 40 inches or more.

Ecological Threat
Its vigorous growth and large leaves smother and shade out native plants. It can kill trees through girdling and the extra weight of vines can lead to toppling during storms. Once established, kudzu plants grow rapidly, extending as much as 60 feet per season, about 1 foot per day.

Bill Johnson

Description and Biology

• Plant: climbing perennial vine in the pea family (Fabaceae); vines may extend 32-100 ft. in length, with stems up to 4 in. in diameter; roots are fleshy, with massive tap roots that can get to 7 in. or more in diameter, 6 ft. or more in length, and weigh as much as 400 lbs.; up to 30 vines may grow from a single plant.
• Leaves: alternate, deciduous, and compound, with three broad leaflets up to 4 in. across, leaflets may be entire or lobed with hairy margins.
• Flowers, fruits and seeds: individual flowers, about ½ in. long, are purple, fragrant and borne in upright clusters during late summer; fruits are brown, hairy, flattened seed pods, each of which may contain as many as ten hard seeds.
• Spreads: expands locally by vegetative means through runners & rhizomes and by vines that root at the nodes to form new plants; may spread by seed in areas where a pollinator, the giant resin bee, occurs.
• Look-alikes: Thick tangles of various vines including grape, porcelainberry and bittersweet may be mistaken for kudzu as well as some native three-leaved vines in the pea family.

Prevention and Biological Control

Do not plant kudzu. The U.S. Department of Agriculture is investigating biological control agents for kudzu including the naturally occurring fungus Myrothecium verrucaria. 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 repeated cutting of vines just above ground level, frequent mowing and cultivation. Use of systemic herbicides with the active ingredients triclopyr and glyphosate have been used effectively (see Control Options).