Kudzu, Pueraria montana, is a climbing, semi-woody, perennial vine in the pea family. Kudzu is common throughout most of the southeastern United States and has been found as far north as Pennsylvania. The name comes from Japanese kazu (葛), meaning vine.
Kudzu vines can make walking across the land nearly impossible, as it takes over all horizontal and vertical surfaces, both natural and manmade. Its dense vegetation obstructs all views and movement into the area. It 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.
Description
Deciduous leaves are alternate and compound, with three broad leaflets up to four inches (10 cm) across. Leaflets may be entire or deeply 2-3 lobed with hairy margins. Leaflets are entire or coarsely and palmately lobed, up to eight inches long, pubescent underneath.
Individual flowers, about ½-inch (1 cm) long, are purple, highly fragrant, tufted at nodes at the rachis, and borne in long hanging clusters (see image). The flowers are copious nectar producers and are visited by many species of bees, butterflies and skippers. Flowering occurs in late summer and is soon followed by production of brown, hairy, flattened, seed pods, each of which contains three to ten hard seeds.
Every part of the plant is edible. The young leaves can be used for salad or cooked as greens; the flowers battered and fried (like squash blossoms); and the starchy roots can be prepared as any root vegetable.
Once established, kudzu plants grow rapidly, extending as much as 60 feet (more than 18 m) per season at a rate of about one foot (30 cm) per day. This vigorous vine may extend 32-100 feet (9.5-30 m) in length, with stems one-half to four inches (1-10 cm) in diameter. Kudzu roots are fleshy, with massive tap roots seven inches (18 cm) or more in diameter, six feet (180 cm) or more in length, and weighing as much as 400 pounds (180 kg). As many as thirty vines may grow from a single root crown.
Kudzu grows well under a wide range of conditions and in most soil types. Preferred habitats are forest edges, abandoned fields, roadsides, and disturbed areas, where sunlight is abundant. Kudzu grows best where winters are mild, summer temperatures are above 80° F (27° C), and annual rainfall is 40 inches (100 cm) or more.
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.
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 involve cutting vines just above ground level and destroying all cut material. Close mowing every month for two growing seasons or repeated cultivation may be effective. Cut kudzu can be fed to livestock, burned or enclosed in plastic bags and sent to a landfill. If conducted in the spring, cutting must be repeated as regrowth appears to exhaust the plant's stored carbohydrate reserves. Late season cutting should be followed up with immediate application of a systemic herbicide (e.g., glyphosate) to cut stems, to encourage transport of the herbicide into the root system. Repeated applications of several soil-active herbicides have been used effectively on large infestations in forestry situations. Efforts are being organized by the U.S. Forest Service to begin a search for biological control agents for kudzu.
History
Kudzu was introduced from Japan into the United States 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 United States Department of Agriculture and, in 1953, was removed from its list of permissible cover plants.