Author: Peter Neofotis
Common Name: Kudzu
Scientific Name: Pueraria montana, also called Pueraria lobata
Identification: A high climbing, trailing, twining deciduous woody vine, kudzu can be seen blanketing forests, abandoned houses, and whatever else might remain in its path. The roots are tuberous and rope like, and the hairy stems can grow to 20 m in length. Along these stems the leaves alternate, long petioled with three dark green hairy leaflets on each leaf. Each leaflet grows up to 15 cm long. The terminal leaflets are three lobed and symmetrical, and the lateral ones are either one or two lobed. Its pea-like flowers are fragrant, reddish purple, 2-2.5 cm across, in short stalked, elongated clusters at the leaf axis, to 20 cm long. Its fruit takes the form of a dark brown pod, flat but bulging over with seeds and densely covered in long golden brown hairs, 8 cm long and 0.8 cm wide.
Kudzu may be confused with dollar leaf (Desmodium rotundifolium) and other three lobed legumes. However, kudzu distinguishes itself by its densely pubescent young stems, ovate/trivolate leaves, and its ability to blanket large areas. Another species, hog peanut (Amphicarpae bracteate) may be confused as young kudzu. But, it does not have pubescent stems or the ability to climb extensively on tree crowns.
In Asia temperate kudzu is found in China, Japan, Korea, and Taiwan. In asia tropical kudzu is in Indonesia, Malaysia, Papua New Guinea, Philippines, Thailand, and Vietnam. Kudzu is also native to Queensland, Australia and, in the Pacific, Fiji, New Caledonia, Solomon Islands, Tonga, and Vanuatu.
Current Distribution: Kudzu is estimated to cover 810,000ha (2,000,000 acres) across southern United States alone. Though normally found only south of New York and east of Texas (area in map), populations have been found as far north as Nova Scotia and and northwest as Oregon. It has also invaded Puerto Rico and South Africa.
Site and Date of Introduction: Kudzu was first introduced to the United States in 1876 at the Centennial Exposition in Philadelphia, Pennsylvania. The Japanese constructed a beautiful garden filled with plants from their country, and American gardeners quickly started using the plant for ornamental purposes.
Mode(s) of Introduction:
In the 1920s, Florida nursery operators Charles and Lillie Pleas discovered that animals would eat the kudzu and promoted its use as forage. In the 1930s, the Soil Conservation Service employed hundreds of young men in the Civilian Conservation Corps to plant the vine for erosion control. In the 1940's, the US Government paid farmers as much as 8 dollars per acre of vine they planted.
Reason(s) Why it has Become Established: Besides escaping native insect predators, the climate of the Southeastern US is perfect for kudzu. The vines grow as much as one foot per day during summer months, climbing anything from trees to power poles to abandoned buses. In addition, kudzu is an extremely hardy plant. It is drought tolerant and frost only harms its above ground portions. The thick storage roots, which form from stem nodes touching the ground, can grow as deep as one meter. They also have a high starch content that allows the plant to grow early in spring and regrow if the vines are damaged in the summer. Flowering in late summer and early fall, kudzu produces a large amounts of seeds which are dispersed by birds and mammals.
Kudzu controls erosion, fixes nitrogen, and can be used as a starch or vegetable for humans. In addition, its chemical composition and digestibility make it suitable as a fed forage for animals such as cattle and sheep. For example, the percentage of crude protein in its leaf and stem is comparable to that in lucerne and bermudagrass hays. Neutral and acid detergent fibre levels in the leaf, stem, and tube parts are also comparable to the values in hays.
Benefit(s): Growing fast and with a strong root system, kudzu is excellent for erosion control. The plant also has agricultural uses. The plant fixes nitrogen and can be used as a feed for pasture animals. Kudzu contains several medical chemicals such as daidzen, used to fight inflammation and microbial infections, dilute coronary arteries, relax muscles, and promote estrous cycles. It also contains daidzin, which is used to prevent cancer, and genistein, an anti-leukemic. Several people throughout the south have found that kudzu's rubber-like vines are excellent for making basket weaving and artistic paper. Others incorporate it in their diet, cooking such things as kudzu quiche and deep-fried kudzu leaves.
Threat(s): Kudzu has and continues to smother forests in the south-eastern United States by preventing them from getting sunlight and breaking them under the weight of its vines. Some forests have been strangled in as little as two to three years. Kudzu also threatens riparian areas and watershed health. Spreading abut 120,000 acres a year, control costs for the vine increase by nearly $ 6 million each year. The spread of kudzu results in a lowering of land productivity, biodiversity, and economic losses in the timber industry.
Control Level Diagnosis: Highest Priority-Attempts to control kudzu must be continued and enhanced. The vine already covers a huge area and is continuing to spread rapidly. If the plant is not addressed, the rate of spread might increase, resulting in enhanced ecological and economic damage. In some states, such as Oregon, kudzu may be the most serious threat to the timber industry.
Mowing: Only repeated mowing can weaken and control kudzu. Though it can be a first step toward control, significant risks are involved. Kudzu can conceal ditches and the thick mats of vines can be difficult to cut with a light duty rotary mower. Flail mowers with horizontal blades that cut in a chopping manner are more effective. If done, close mowing makes the treatment of regrowth much easier, reducing the tangle of leaves and vines.
Grazing: The prospect of using kudzu for grazing was a reason for its planting in the US. Indeed, the plant is comparable in nutritional value and digestibility to other commonly used forages. To control kudzu by grazing, though, it is necessary to fence in the entire patch. Only by repeatedly grazing growth over several seasons will the root stores be depleted.
Such grazing projects are already underway. As of September 2001, 600 sheep were gnawing kudzu in Tallahassee, Florida and dozens more were dining in smaller sites around New England. Also, Dr. Errol G. Rhoden, with researchers at Tuskegee University, is raising Angora goats in fields of kudzu. While keeping the vine from spreading further, the goats also produce milk and wool products. Rhoden says a constant grazing will eventually eradicate the kudzu.
Burning: Controlled burning can be used so that a site can be inspected to determine the size and density of the root crowns. However, burning should be done in either winter or spring, with spring the more desirable as to limit the exposure of the bare soil to winter rains and limit soil erosion.
Herbicides: Herbicides are a common and expensive option to control of kudzu. Several herbicides are labelled for kudzu control, and different ones are recommended depending on the the type of nearby plant or tree that kudzu has covered. Some herbicides make kudzu grow better and many have little or no effect. At least four years of repeated treatments are recommended. Some kudzu takes as long as ten years to kill, even with the most effective herbicide.
Biological Control- In a recent experiment, Myrothecium verrucaria, a fungus native to the Southeastern United States, has been found to be an effective pathogen against kudzu grown in the greenhouse and field. In addition, though the fungus, acquired from naturally infected sickle pod, can produce toxins in a variety of substrates, it does not in kudzu tissues. The results argue that the fungus can be used safely as a biological control of kudzu and supports proceeding to animal feeding trials for further evaluation of its safety.
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