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Taxonomic name: Pueraria montana var. lobata (Willd.) Maesen & S. Almeida Synonyms: Dolichos hirsutus Thunberg, Dolichos lobatus Willd., Pachyrrhizus thunbergianus Siebold & Zuccarini, Pueraria hirsuta (Thunb.) C. Schneider, Pueraria lobata var. thomsonii (Benth.) Maesen, Pueraria lobata (Willd.) Ohwi, Pueraria montana (Lour.) Merr. var. lobata (Willd.), Pueraria thunbergiana (Sieb. & Zucc.) Benth. Common names: acha, aka, foot-a-night vine (English), Japanese arrowroot (English), Ko-hemp, Kopoubohne (German), kudzu (English), kudzu común (Spanish), kudzu vine (English), Kudzu-Kletterwein (German), kuzu (Japanese), nepalem, vigne japonaise (French), vine-that-ate-the-South (English), wa yaka Organism type: vine, climber Kudzu (Pueraria montana var. lobata ) roots can comprise over 50% of the plant’s biomass, serving as an organ for carbohydrate storage for recovery after disturbance and making it difficult to control the weed with herbicides. Only in the southeastern United States is kudzu considered a serious pest, however, it is recently established and invasive in Europe in Italy and Switzerland. Impacts of kudzu include loss of productivity of forestry plantations (estimated at about 120 USD per hectare per year) and smothering and killing of native plants. Description Kudzu is an aggressive, climbing semi-woody perennial vine. Vegetative growth can be very rapid (up to 26 centimeters per day or 15 meters per growing season). Stems are herbaceous to woody, 10 to 30 meters long, up to 2.5 centimeters thick; young vines are covered with tan to bronze hairs. Leaves are alternate with three leaflets (hairy on both surfaces) eight to 20 centimeters long and five to 19 centimeters wide, usually slightly lobed (unless in shade). Flowers are pea-like, pink to purple with yellow centres, borne in long hanging panicles similar to wisteria (10 to 25 centimeters long) and have the fragrance of Concord grapes (Vitis sp.). Flowers are produced on plants exposed to direct sunlight. Flowers and fruits are produced only on vertically growing vines. The four to five centimeter long seed pods are relatively flat, hairy and mature in early fall splitting on one or both sides to release three to 10 seeds. The pods produce only a few viable seeds in each pod cluster. The compressed kidney-shaped seeds are nearly round and about three to four millimeters long (Frankel 1989, USDA 1976, Uva et al. 1997, Virginia Native Plant Society 1999, in Mitich 2000). Kudzu also possesses large root tubers up to two meters long and 18 to 45 centimeters wide that can weigh as much as 180 kilograms on old plants and can reach a depth of one to five meters with high starch and water contents (EPPO 2007). Roots can comprise over 50% of the plant’s biomass (Wechsler 1977, in Newton et al. 2007), serving as a storage organ for carbon and water (Forseth & Innis 2004). This description was taken from Mitich 2000 and EPPO 2007 except where stated. Occurs in: agricultural areas, natural forests, planted forests, range/grasslands, riparian zones, ruderal/disturbed, scrub/shrublands, urban areas Habitat description The typical natural habitat of kudzy is broad-leaved or mixed forests, but it readily invades managed habitats such as road and rail embankments, pastures, conifer plantations, banks of inland water bodies (EPPO 2007). It colonises a wide variety of natural and seminatural habitats (EPPO 2007), for example forest edges, disturbed areas or scrub vegetation (van der Maesen 1985 1994 2002, Halim 1992, in Heider et al. 2007). Whereas tropical kudzu (P. phaseoloides) thrives in humid and low altitude habitats, kudzu prefers warm to temperate zones or higher altitudes (van der Maesen 1985 1994 2002, Halim 1992, in Heider et al. 2007). Kudzu can survive in both sun and shade habitats, but it does best in high-light forest edge areas (Abramovitz 1983, Forseth & Teramura 1987, in Forseth & Innis 2004). Kudzu grows well with precipitation of 1000 to 1500mm on sand or clay soil (Sun et al. 2006). Because of its large roots, which act as water reservoirs, kudzu can also withstand fairly dry climates (Shurtleff and Aoyagi 1977, in Mitich 2000; Zhang & Ye 1990, in Sun et al. 2006). It prefers high summer temperatures (over 27°C) and deep, well-drained loamy soils; the plant is able to survive in frosted and shallow soils even though its roots cannot develop fully (Pron 2006, in EPPO 2007). It is relatively indifferent to soil pH; according to soil analyses the plant can grow in soils with a soil pH from 3 to 8 (EPPO 2007). In Japan, kudzu ranges in latitude from 44°N to 30°N. It grows abundantly in mountainous areas up to an elevation of 1 000 m; it is also found in lowland areas and on many of the small islands. In Korea, it grows in areas where the temperature drops to -30°C (Shurtleff and Aoyagi 1977, in Mitich 2000). General impacts For a detailed account of the environmental impacts of P. montana var lobata please read: Pueraria montana (Kudzu) Impacts Information. The information in this document is summarised below. Kudzu is widely believed to drastically reduce biodiversity because of its ability to smother other vegetation and develop large-scale monocultures (Alderman 1998, Forseth and Innis 2004, in Sun et al. 2006). Kudzu is an aggressive vine that currently dominates an estimated 810 000 hectares of mesic forest in the eastern United States (Harrington Rader-Dixon & Taylor 2003). It can climb overtop and subsequently kill new seedlings or mature trees (Berisford Bush & Taylor 2006). Forestry problems associated with aggressive vines such as kudzu include mortality of edge trees, exclusion of native plant species, and potential to increase fire hazard during winter (Putz 1991, in Harrington Rader-Dixon & Taylor 2003). Kudzu dominates other plants by climbing over and shading everything in its path, killing native herbaceous and woody species. Because of this, the U.S. Congress listed kudzu as a federal noxious weed in July 1997, Harrington Rader-Dixon & Taylor 2003). Ecosystem Change: Few plants can survive once smothered by kudzu and small ecosystems could be radically altered. The plant quickly develops, rapidly covering the soil, affecting indigenous plants and completely modifying the structure of the ecosystem (Clabassi et al. 2003, in EPPO 2007). Kudzu may have a disproportionate effect on animals with specific mutualisms or feeding relationships with trees or shrubs suppressed by its growth (Forseth & Innis 2004). Reduction in Native Biodiversity: Kudzu is invading National Parks in the USA and when it does encroach on natural areas it kills trees and plants by growing over them (EPPO 2007). Pron (2006, in EPPO 2007) found that there was a reduction in the number of species in invaded places: while 20 to 25 species grew in 4 m² of non-invaded meadow or forest, only 6 to 9 species grew in 4 m² invaded by kudzu. Competition: Key traits of kudzu that contribute to its ability to spread rapidly and dominate natural communities are its high allocation to extension growth and leaf area instead of support structures; frequent rooting of stems at nodes in contact with the soil, rapid leaf movements, high leaf level photosynthetic rates accompanied by high leaf area indices, large hydraulic capacitance in roots and rhizomes, and the ability to fix atmospheric N2 (Forseth & Innis 2004). This unique combination of traits makes P. montana an extremely aggressive competitor in the eastern deciduous and southeastern USA mixed pine forest biomes (Forseth & Innis 2004). Disease Transmission: The pest could be a reservoir for soybean rust and Phytophthora species (EPPO 2007). Modification of Nutrient Regime: Pueraria montana forms a dense root mat and annually produces a thick leaf litter layer with high leaf nitrogen due to its nitrogen-fixing properties (Forseth & Innis, 2004). Kudzu has a symbiotic relationship with nitrogen-fixing bacteria (Rhizobium spp.) in root nodules and can almost double the concentration of nitrogen compounds in the topsoil (1 to 6 cm deep) (Pron 2006, in EPPO 2007). Economic/Livelihoods: As a rapidly growing vine, kudzu can cover and smother orchard and plantation crops, including young forest plantations. Where productive forest land has been overtaken, lost productivity is estimated at about 120 USD per hectare per year (EPPO 2007). Lost productivity in forests has been estimated at anywhere between $100 to 500 million per year (Blaustein 2001, Quimby et al. 2003, in Forseth & Innis 2004). Uses Kudzu’s greatest potential today may be the powdery extract derived from the plant's roots and used as cooking starch. Kudzu leaves, shoots, and flowers are used in salads, soups, sauteed dishes and casseroles. Kudzu has medicinal properties and has been used for millennia in China and Japan to cure a wide range of common ailments (Shurtleff & Aoyagi 1977, in Mitich 2000). In Japan, young kudzu vines are harvested to provide supple waterproof fibers for weaving sturdy wicker baskets or trunks. The cellulose fiber from large vines and roots is used as the basic raw material for making fine traditional paper. The fiber is also used to stuff cushions, beds, and chairs. When burned, it acts as a mosquito repellent (Shurtleff & Aoyagi 1977, in Mitich 2000). Kudzu has been used to produce an unusually fragrant, flavorful honey. Its leguminous roots host nitrogen-fixing bacteria that enrich the soil (Shurtleff and Aoyagi 1977, in Mitich 2000). Kudzu has also been successfully used in the experimental production of methane and gasohol (Hipps 1994, in Mitich 2000). The main uses of kudzu in the United States have been for erosion control and as a forage crop; while kudzu is still valued as a soil-conserving plant for erosion control on steep slopes and embankments, less invasive species are now available for stabilization purposes (Birdsall & Hough-Goldstein 2004). These uses of kudzu have been taken from Mitich 2000 except where stated. Notes Climate Change: Jarnevich & Stohlgren (2009) examined how the potential distribution of kudzu will be affected by changing climate and created habitat suitability models that indicate that P. montana may increase its distribution particularly in the Northeast United States with climate change and may decrease in other areas. Predictions of global warming include increases of 3°C to 5°C in mean global temperatures (IPCC 2001, in Forseth & Innis 2004). These trends should favor the spread of P. montana (Forseth & Innis 2004). Kudzu has recently showed northward and westward migration patterns in the United States that correlate with warmer winters and higher CO² levels (Ziska et al. 2009). Related Species: P. montana var. lobata is the variety that has been introduced into the United States and South America. The range of this variety overlaps with that of P. montana var. montana in China south of the Yangtze River to Hong Kong. The distribution of P. montana var. montana also includes Vietnam, Burma, Laos and Thailand. In these countries, and in southern China, P. montana var. montana shares its distribution with P. montana var. thomsoni. Specimens from northeast India were identified as P. montana var. thomsoni (van der Maesen 1985, in Britton et al. 2002). This profile pertains to Pueraria montana var. lobata. Characteristics that had been used previously to differentiate P. montana from P. lobata and Pueraria thomsoni (Benth.) are lobed leaflets, and the size of wing and keel petals, all of which can be quite variable. For information on the taxonomy of P. montana please see Ward (1998). Geographical range Native Range: Van der Maesen (1985, in Britton et al. 2002) considered China, Indo-China, Japan, Malaysia, Oceania and the Indian subcontinent the native range of the genus Pueraria. Within this region kudzu is native to subtropical and temperate Eastern Asia in regions of Japan, Korea, China (north of Shanghai), the Philippines, Malaysia and Indonesia (Van der Maesen 1985, in Britton et al. 2002). Kudzu is widely distributed in China except in the Xiangjiang Autonomous Region, Quinghai and Tibet (Sun et al. 2006). Known Introduced Range: Kudzu is mainly invasive in the southern USA and, more recently, has become a minor invasive in parts of Italy and Switzerland (EPPO 2007). Introduction pathways to new locations Agriculture: The main potential pathway for entry of the plants into new areas is the movement and sale of plants for horticulture and agriculture (EPPO 2007). For ornamental purposes: After its introduction in the USA in 1876 P. montana was marketed as an ornamental plant and shade for porches in hot southern summers (Miles and Gross 1939, Edmisten and Perkins 1967, Blaustein 2001, in Forseth & Innis 2004). Internet sales/postal services: Kudzu seeds were widely available through mail-order catalogs in the USA in the late 1800s (Tabor 1942, McKee & Stephens 1943, Bailey 1944, Nixon 1948, in Forseth & Innis 2004) and advertised in catalogs as "porch vine" (Waldner 2008). Natural dispersal: Kudzu spreads locally by runners (EPPO 2007). Vegetative spread is thought to be responsible for most of the estimated 50 000 hectares increase in P. Montana cover each year in the United States (Forseth & Innis 2004). Road vehicles (long distance): Local dispersal methods Consumption/excretion: Kudzu spreads over moderate distances by dispersal of seeds by mammals and birds. Garden escape/garden waste: In Switzerland, plant waste has been found in many infested sites, therefore garden waste is thought to be a pathway (Pron 2006, in EPPO 2007). Road vehicles: Translocation of machinery/equipment (local): Water currents: Management information For a detailed account of the environmental impacts of Pueraria montana var lobata please read: Pueraria montana var lobata (Kudzu) Management Information. The information in this document is summarised below. Various management and eradication programs have been explored to control the spread of kudzu in the USA, including intensive herbicide application, livestock grazing, industrial use of the plant, and use of the plant pathogen Pseudomonas syringae pv. phaseolicola (Tanner et al. 1979, Miller & Edwards 1983, Bonsi et al. 1992, Miller 1996, Harrington et al. 2003, Britton et al. 2002, in Sun et al. 2006). Preventative Measures: A Risk assessment of Pueraria montana var. lobata for Australia and the Pacific was prepared by Pacific Island Ecosystems at Risk (PIER); the result is a score of 9 and the plant is considered likely to be a pest in the Pacific. Physical Control: Burning and grazing may be effective in some cases but are impractical in most heavily infested areas such as urban areas and near highways (Everest et al. 1994, in Boyette Walker & Abbas 2002). Heavy grazing by cows, pigs, horses or goats (Rhoden et al. 1991, in EPPO 2007) can remove kudzu. However animals cannot eat vines growing over trees or in steep areas, watering holes must be provided and there must be enough livestock to ensure 80% of the plant is continuously consumed (Ball et al. 1979, Miller & Edwards 1983, in EPPO 2007). Chemical Control: Clopyralid, picloram, triclopyr, metsulfuron and tebuthiuron exert various degrees of control, depending on soil type, meteorological conditions, herbicide formulation, seasonal application, characteristics of the kudzu stand, and frequency and number of herbicide applications (Kay & Yelverton 1998, Miller 1996, in Berisford Bush & Taylor 2006). When used as part of a forest regeneration program, the relative potentials of the herbicides to move into shallow groundwater were: tebuthiuron > picloram > metsulfuron > clopyralid > triclopyr (Berisford Bush & Taylor 2006). Biological Control: Biological control is potentially an important element of an integrated management system for kudzu, but is only at the experimental stage so far (EPPO 2007). A three-year survey of kudzu for associated phytophagous insects was conducted to establish basic information about the insect communities that kudzu harbors in China and to assess the abundance, diversity and damage caused by these insects. Diseases of kudzu were also surveyed in southern China. A total of 116 phytophagous insect species in 31 families and five orders were collected from kudzu in China, in six feeding guilds: foliage, sap, stem, terminal, seed and root feeders. Several of these species have potential as biological control agents for kudzu in the USA (Sun et al. 2006). For a full list of phytophagous insects collected from kudzu in China between 1999 and 2001 please see Sun et al. (2006). Integrated Pest Management (IPM): The application of polyethylene sheeting as a thermal covering is a non-herbicidal method of controlling and eradicating kudzu (Newton et al. 2007). This type of thermal treatment is an effective method in an Integrated Pest Management programme used to restore these areas to their native vegetation (Newton et al. 2007). For information about the potential use of kudzu as an agricultural and industrial resource see Tanner et al. (1979). Nutrition Kudzu can be found growing in a wide range of soil types with little to no special nutrient requirements. Reproduction The mating system of P. lobata includes both sexual reproduction through bee pollination and asexual reproduction through rhizome spread (Sun et al. 2005). Sexual: The large purple flowers of Pueraria are produced in relative abundance with a sweet aroma; its corolla (petals) is papilionaceous (shaped like a butterfly) and 14 to 20 mm long (Sun et al. 2005). Kudzu is insect-pollinated, and the extremely low viability of seeds in its introduced range is assumed to be due to a lack of suitable pollinators (EPPO 2007). Thornton (2001, in Forseth & Innis 2004) reported visitation by several native and naturalized pollinators, the most prominent being native hymenoptera. Insect predation of seeds has been reported to average over 80% for populations in North Carolina, and reports of successful seedling establishment remain rare (Kidd 2002, in Forseth & Innis 2004). Asexual: Kudzu roots easily from nodes and has a large tuberous root system, producing extensive clonal spread (Pappert Hamrick & Donovan 2000). Little biomass is allocated for structural support, allowing kudzu to invest its resources into vine expansion and increased photosynthetic area (Sasek & Strain, 1988, in Pappert Hamrick & Donovan 2000). Lifecycle stages Seedlings develop a woody root crown, with multiple runners and extensive tuberous roots (Britton et al. 2002). This species has been nominated as among 100 of the "World's Worst" invaders Reviewed by: Expert review underway: Dr. James H. Miller, USDA Forest Service, Southern Research Station, Auburn, AL 36849 USA. Compiled by: Profile revision: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG) To contribute information, please contact Shyama Pagad. Last Modified: Monday, November 28, 2005