Kudzu

Kudzu (Pueraria lobata, and possibly other species in the genus Pueraria; see taxonomy section below) is a plant in the genus Pueraria in the pea family Fabaceae, subfamily Faboideae. It is a climbing, coiling, and trailing vine native to southern Japan and southeast China. Its name comes from the Japanese name for the plant, Kuzu (クズ or 葛^?).

Kudzu is sometimes called gé gēn (Chinese: 葛根), and (due to its out-of-control growth in the Southeastern United States) has earned such pejorative nicknames as the "foot-a-night vine", "mile-a-minute vine", and "the vine that ate the South" (of the United States).

In Vietnam, it is called sắn dây.

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Taxonomy and nomenclature

Five species in the genus Pueraria are closely related and the name kudzu describes one or more of them. They are P. montana, P. lobata, P. edulis, P. phaseoloides and P. thomsoni^{[citation needed]}. The morphological differences between the five species are subtle, they can breed with each other, and it appears that introduced kudzu populations in the United States have ancestry from more than one of the species. The name Pueraria thunbergiana is a synonym for Pueraria montana var. lobata.

Propagation

Kudzu spreads by vegetative expansion, via stolons (runners) that root at the nodes to form new plants and by rhizomes. Kudzu will also spread by seeds, which are contained in pods and mature in the autumn, although this is rare.^{[citation needed]} One or two viable seeds are produced per cluster of pods. The hard -coated seeds may not germinate for several years, which can result in the re-appearance of the species years after it was thought eradicated at a site.^{[citation needed]}

Uses

Soil improvement and preservation

Kudzu has been used as a form of erosion control and also to enhance the soil. As a legume, it increases the nitrogen in the soil via a symbiotic relationship with nitrogen-fixing bacteria in the soil. Its deep taproots also transfer valuable minerals from the subsoil to the topsoil, thereby improving the topsoil. In the deforested section of the Central Amazon Basin in Brazil, it has been used to improve the soil pore-space in clay latosols and thus freeing even more water for plants than in the soil prior to deforestation.

Animal feed

Kudzu can be used by grazing animals as it is high in quality as a forage and greatly enjoyed by livestock. It can be enjoyed up until frost and even slightly after. Kudzu hay typically has a 15–18% crude protein content and over 60% total digestible nutrient value. The quality of it decreases, however, as vine content increases relative to the leaf content. Kudzu also has low forage yields despite its great deal of growth, yielding around two to four tons of dry matter per acre annually. It is also difficult to bale due to its vining growth and its slowness in shedding water. This makes it necessary to place kudzu hay under sheltered protection after being baled. Kudzu is readily consumed by all types of grazing animals, yet frequent grazing over 3 to 4 years can ruin stands. Thus kudzu only serves well as a grazing crop on a temporary basis.

Medicine

Kudzu leaves

The Harvard Medical School is studying kudzu as a possible way to treat alcoholic cravings, by turning an extracted compound from the herb into a medical drug. The mechanism for this is not yet established, but it may have to do with both alcohol metabolism and the reward circuits in the brain.

Kudzu also contains a number of useful isoflavones, including daidzein (an anti-inflammatory and antimicrobial agent). Daidzin is a cancer preventive and is structurally related to genistein (an antileukemic agent). Kudzu is a unique source of the isoflavone puerarin. Kudzu root compounds can affect neurotransmitters (including serotonin, GABA, and glutamate.) It has shown value in treating migraine and cluster headaches. It is recommended for allergies and diarrhea.

Research in mice models suggests that kudzu is beneficial in women for control of some postmenopausal symptoms, such as hypertension and diabetes type II.

In traditional Chinese medicine(TCM), where it is known as gé gēn (Chinese: 葛根), kudzu is considered one of the 50 fundamental herbs. It is used to treat tinnitus, vertigo, and Wei syndrome (superficial heat close to the surface).^{[citation needed]}

Kudzu has been traditionally been used as a remedy for alcoholism and hangover in China. The root was used to prevent excessive consumption, while the flower was supposed to detoxify the liver and alleviate the symptoms afterwards. Some TCM hangover remedies are marketed with kudzu as one of their active ingredients (e.g. Hangover Busters.)

Starch

Kudzu starch cake

The roots contain starch, which has traditionally been used as a food ingredient in East Asia.

In Vietnam, the starch called bột sắn dây is flavoured with pomelo oil and then used as a drink in the summer.

Other uses

In the Southern United States, kudzu is used to make soaps, lotions, jelly, and compost. It has even been suggested that kudzu may become a valuable asset for the production of cellulosic ethanol.

The fiber is used traditionally and has also been investigated for potential uses such as clothing, wallpaper, and paper.

Ecological invasion

United States

Kudzu growing on trees

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 early 1950s, the Soil Conservation Service encouraged farmers in the southeastern United States to plant kudzu to reduce soil erosion as explained above. The Civilian Conservation Corps planted it widely for many years.

Kudzu growing on shrubs

It was subsequently discovered that the southeastern US has near-perfect conditions for kudzu to grow out of control — hot, humid summers, frequent rainfall, temperate winters with few hard freezes (kudzu cannot tolerate low freezing temperatures that bring the frost line down through its entire root system, a rare occurrence in this region), and no natural predators. As such, the once-promoted plant was named a pest weed by the United States Department of Agriculture in 1953.

Infestation of Kudzu in the United States.

Kudzu is now common throughout most of the southeastern United States, and has been found as far northeast as Paterson, New Jersey, in 30 Illinois counties including as far north as Evanston, and as far south as Key West, Florida.^{[citation needed]} It has also been found growing in Clackamas County, Oregon in 2000 with no known source. This is the first infestation west of Texas. Kudzu has naturalized into about 20,000 to 30,000 square kilometers (7,700–12,000 sq mi) of land in the United States and costs around $500 million annually in lost cropland and control costs.

Canada

Kudzu was discovered July 2009 in a small patch, 110 metres wide and 30 metres deep, on a south-facing slope on the shore of Lake Erie near Leamington, Ontario, about 50 kilometres southeast of Windsor.

Ecologist Gerald Waldron made the Leamington find while walking along the beach. He spotted the kudzu instantly, having read about its destructive expansion in the southeastern United States.^{[citation needed]}

Other countries

During World War II, kudzu was introduced to Vanuatu and Fiji by United States armed forces to serve as camouflage for equipment.^{[citation needed]} It is now a major weed.

Kudzu is also becoming a problem in northeastern Australia, and has been seen in isolated spots in Northern Italy (Lago Maggiore).

Negative effects

Scientists at the University of Virginia and Columbia University have discovered that the kudzu vine activates isoprene, nitric oxide, and nitrogen in a chemical reaction which produces ground-level ozone. [1]

Control

According to ScienceDaily, kudzu has been spreading in the southern U.S. at the rate of 150,000 acres (61,000 ha) annually, "easily outpacing the use of herbicide spraying and mowing, as well increasing the costs of these controls by $6 million annually." Its introduction has produced devastating environmental consequences.

Crown removal

For successful long-term control of kudzu, it is not necessary to destroy the entire root system, which can be quite large and deep. It is only necessary to use some method to kill or remove the kudzu root crown and all rooting runners. The root crown is a fibrous knob of tissue that sits on top of the root (rhizome). Crowns form from vine nodes that root to the ground, and range from pea-size to basketball-size. The older the crown, the deeper they tend to be found in the ground, because they are covered by sediment and plant debris over time. Nodes and crowns are the source of all kudzu vines, and roots cannot produce vines. If any portion of a root crown remains after attempted removal, the kudzu plant may grow back.

Small kudzu crown severed from root using flexible pruning saw.

Mechanical methods of control involve cutting off crowns from roots, usually just below ground level. This immediately kills the plant. Cutting off vines is not sufficient for an immediate kill. It is necessary to destroy all removed crown material. Buried crowns can regenerate into healthy kudzu. Transporting crowns in soil removed from a kudzu infestation is one common way that kudzu "miraculously" spreads and shows up in unexpected locations.

Mowing

Close mowing every week, regular heavy grazing for many successive years, or repeated cultivation may be effective, as this serves to deplete root reserves. If done in the spring, cutting off vines must be repeated as regrowth appears to exhaust the plant's stored carbohydrate reserves. Cut kudzu can be fed to livestock, burned, or composted, strides have been made in using it for vehicle fuel as ethanol.^{[citation needed]}

Grazing

The city of Chattanooga, Tennessee has undertaken a trial program using goats and llamas that graze on the plant. The llamas serve double-duty as defense against predators due to their aggressive nature. As of 2007 the goats are grazing along the Missionary Ridge area in the east of the city.

Fire

Prescribed burning is also used on old extensive infestations to remove vegetative cover and promote seed germination for removal or treatment. It is usually done to prepare for treatment of the root crowns. Landscape equipment, such as a skid loader ("Bobcat"), can also remove biomass. While fire is not an effective way to kill kudzu, equipment, such as skid loaders, can remove crowns and thereby kill kudzu with minimal disturbance of soil.

Kudzu infestation along the Kanawha River in West Virginia.

Herbicide

To properly manage kudzu, stem cutting should be immediately followed with the application of a systemic herbicide; for example, glyphosate, Triclopyr, or Tordon, directly on the cut stem. This process is an effective means of transporting the herbicide into the kudzu's extensive root system. The usage of herbicides can be combined with other methods of eradication and control, such as mowing, grazing, or burning, which can allow for an easier application of the chemical to the weakened plants. When it comes to large-scale forestry infestations, soil-active herbicides have been shown to be highly effective.

After initial herbicidal treatment, follow-up treatments and monitoring are usually necessary, depending on how long the kudzu has been growing in the area. It may require up to ten years of supervision, after the initial chemical placement, to make sure the plant does not return in the future.

Herbicides which have been proven to be effective to control kudzu are claimed to be "rather safe to humans, but generally lethal on most plants."

Fungi

Since 1998, the United States Department of Agriculture, Agricultural Research Service (ARS) has experimented with using the fungus Myrothecium verrucaria as a biologically-based herbicide against kudzu. A diacetylverrucarol spray based on M. verrucaria works under a variety of conditions (including the absence of dew), causes minimal injury to many of the other woody plants in kudzu-infested habitats, and takes effect fast enough that kudzu treated with it in the morning starts showing evidence of damage by mid-afternoon. Initial formulations of the herbicide produced toxic levels of trichothecene as a by-product, though the ARS discovered that growing M. verrucaria in a fermenter on a liquid instead of a solid diet limited or eliminated the problem.

See also

• Chinese herbology
• Daidzein
• Daidzin
• Puerarin

References

• Part of this article was based on content from public domain web pages from the United States National Park Service and the United States Bureau of Land Management

External links

• Species Profile - Kudzu, National Invasive Species Information Center, National Agricultural Library
• Kudzu from the U.S. National Park Service website
• Kudzu in Georgia from the New Georgia Encyclopedia
• Pesky vine is invading southern West Virginia, an August 2006 article from The Register-Herald of West Virginia