| Kudzu | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Rosids |
| Order: | Fabales |
| Family: | Fabaceae |
| Genus: | Pueraria |
| Species: | P. lobata |
| Binomial name | |
| Pueraria lobata (Willd.) Ohwi |
|
Kudzu ( /ˈkʊdzuː/; 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?). It is a weed that climbs over trees or shrubs and grows so rapidly that it kills them by heavy shading.[1] The plant is edible, but often sprayed with herbicides.[1].
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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.[2] 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.[2][3] The name Pueraria thunbergiana is a synonym for Pueraria montana var. lobata.[4][5] P. tuberosa, a species from the Indian subcontinent, is also known as kudzu.
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. 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 reappearance of the species years after it was thought eradicated at a site.
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.[6] 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 for improving the soil pore-space in clay latosols, and thus freeing even more water for plants than in the soil prior to deforestation.[7]
Kudzu can be used by grazing animals as it is high in quality as a forage and palatable to livestock. It can be grazed until frost and even slightly after. Kudzu had been used in the southern United States specifically to feed goats on land that had limited resources. Kudzu hay typically has a 15–18% crude protein content and over 60% total digestible nutrient value. The quality of the leaves decrease, 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.[1]
Kudzu fiber has long been used for fiber art and basketry. The long runners which propagate the kudzu fields and the larger vines which cover trees make excellent weaving material. Some basket makers use the material green. Others use it after splitting it in half, allowing it to dry and then re-hydrating it using hot water. Both traditional and contemporary basketry artists use kudzu.
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.[8] 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) and daidzin (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.[9] It is recommended by some for allergies and diarrhea.[10]
Research in mice models suggests that kudzu is beneficial in women for control of some postmenopausal symptoms, such as hypertension and diabetes type II.[11]
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).
Kudzu has traditionally been used as a remedy for alcoholism and hangover in China.[12] The root was used to prevent excessive consumption, while the flower was supposed to detoxify the liver and alleviate the symptoms afterwards.[13] Some TCM hangover remedies are marketed with kudzu as one of their active ingredients. This has also been a common use in areas of the Southeastern United States.
It has also shown potential in animal models of Alzheimer's disease.[14]
It may help diabetes and cardiovascular disease.[15]
The roots contain starch, which has traditionally been used as a food ingredient in East Asia.
In Japan, the plant is known as kuzu and the starch named kuzuko. Kuzuko is used as in dishes including kuzumochi, mizu manjū, and kuzuyu.
In Vietnam, the starch called bột sắn dây is flavoured with pomelo oil and then used as a drink in the summer.
Kudzu is called gé gēn (Chinese: 葛根) in China, where it is cooked and eaten.[16]
The flowers are used to make a jelly.[17]
Roots, flowers, and leaves of Kudzu show antioxidant activity that suggests food uses.[17]
Kudzu fiber, known as ko-hemp,[18] is used traditionally to make clothing and paper,[19] and has also been investigated for industrial-scale use.[20][21] The stems are traditionally used for basketry.[22]
Kudzu has also been used for centuries in East Asia to make tea and health tonics.[23] Kudzu powder is used in Japan to make a sort of herbal tea called kuzuyu.
It has been suggested that kudzu may become a valuable asset for the production of cellulosic ethanol.[24]
In the Southern United States, kudzu is used to make soaps, lotions, and compost.[25]
Kudzu was introduced from Japan into the United States at the Japanese pavilion in the 1876 Centennial Exposition in Philadelphia.[23] It is now common along roadsides and other undisturbed areas throughout most of the southeastern United States. Kudzu has been spreading at the rate of 150,000 acres (61,000 ha) annually.[26]
Kudzu was discovered July 2009 in a patch 110 m (360 ft) wide and 30 m (98 ft) deep, on a south-facing slope on the shore, of Lake Erie near Leamington, Ontario, about 50 km (31 mi) southeast of Windsor.[27] Leamington is located in the second warmest growing region of Canada after south coastal British Columbia.
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.
During World War II, kudzu was introduced to Vanuatu and Fiji by United States Armed Forces to serve as camouflage for equipment. 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 (Lake Maggiore).
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[28] 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.[28] 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.
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.
Close mowing every week, regular heavy grazing for many successive years, or repeated cultivation may be effective, as this serves to deplete root reserves.[28] 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.
The city of Chattanooga, Tennessee has undertaken a trial program using goats and llamas that graze on the plant. As of 2007[update] the goats are grazing along the Missionary Ridge area in the east of the city.[29] Similar efforts to reduce widespread nuisance kudzu growth have also been undertaken in the cities of Winston-Salem, North Carolina [30] and Tallahassee, FL.[31]
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.[32] Landscape equipment, such as a skid loader ("Bobcat"), can also remove biomass. While fire is not an effective way to kill kudzu,[28] equipment, such as skid loaders, can remove crowns and thereby kill kudzu with minimal disturbance of soil.[28]
To properly manage kudzu, stem cutting should be immediately followed with the application of a systemic herbicide; for example, glyphosate,[33] Triclopyr,[33] or Tordon,[34] directly on the cut stem.[35] 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.[36] When it comes to large-scale forestry infestations, soil-active herbicides have been shown to be highly effective.[35]
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.[37]
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."[38]
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.[26] 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.[26] 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.[26]
In 2010, sixteen-year-old Jakob Schindler designed a device that allows him to drill into the ground and dispense helium which kills the kudzu while reportedly leaving other plants unharmed.[39] Effectiveness varies and further research is needed to identify the effect of factors such as the season, the soil, and the age of the kudzu.[40]