History

Kudzu was introduced into the U.S. in 1876 at the Philadelphia Centennial Exposition, where it was promoted as a forage crop and an ornamental plant. From 1935 to the mid-1950s, farmers in the south were encouraged to plant kudzu to reduce soil erosion, and Franklin D. Roosevelt's Civilian Conservation Corps planted it widely for many years. Kudzu was recognized as a pest weed by the U.S. Department of Agriculture and, in 1953, was removed from its list of permissible cover plants.

Biology

The spread of kudzu in the U.S. is currently limited to vegetative expansion by runners and rhizomes and by vines that root at the nodes to form new plants. Kudzu also spreads somewhat through seeds, which are contained in pods, and which mature in the fall. However, only one or two viable seeds are produced per cluster of pods, and these hard-coated seeds may not germinate for several years. This vigorous vine may extend 32-100 feet in length, with stems 1/2 - 4 inches in diameter. Kudzu roots are fleshy, with massive tap roots 7 inches or more in diameter and 6 feet or more in length, and weighing as much as 400 pounds. As many as thirty vines may grow from a single root crown.

Ecology

Kudzu kills or degrades other plants by smothering them under a solid blanket of leaves, by girdling woody stems and tree trunks, and by breaking branches or uprooting entire trees and shrubs through the sheer force of its weight. Once established, kudzu plants grow rapidly, extending as much as 60 feet per season at a rate of about one foot per day.

Impact

Kudzu forms dense species-restricted infestations. Kudzu is a semiwoody vine, a legume, with a twining and trailing growth habit that can form dense infestations covering ground and trees. It is reported to infest about 2 to 3 million hectacres in the Eastern U.S., and results in estimated losses of $500US million per year in land productivity and control costs.

Control

Repeated herbicide treatments and overgrazing have been the most used and successful control treatments, followed by pine and pasture grass planting. Bulldozing is used prior to development for elimination in selected sites. 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.

References on the Web:

Global Invasive Species Database

Alien Plant Working Group

The Nature Conservancy