Kudzu in the United States
Encyclopedia
Kudzu
is a serious invasive plant in the United States
. It has been spreading in the southern U.S. at the rate of 150000 acres (60,702.9 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.
(Pueraria montana
) is a perennial
vine native to Southeast Asia
, primarily subtropical
and temperate regions of China
, Japan
, and Korea
, with trifoliate
leaves composed of three leaflet
s. Each leaflet is large and ovate
with two to three lobe
s each and hair on the underside. The leaves have the ability to fix atmospheric nitrogen
, which can supply up to 95% of leaf nitrogen
to the plant in poor soils. Along the vines are nodes
, points at which stems or tendril
s can propagate to increase support and attach to structures. As a twining vine
, kudzu uses stems
or tendrils that can extend from any node on the vine to attach to and climb most surfaces. In addition, the nodes of the kudzu vine have the ability to root when exposed to soil, further anchoring the vine to the ground. The roots are tuberous and are high in starch and water content, and the twining of the plant allows for less carbon concentration in the construction of woody stems and greater concentration in roots, which aids root growth. The roots can account for up to 40% of total plant biomass.
Kudzu’s primary method of reproduction is asexual
vegetative spread (cloning)
which is aided by the ability to root wherever a stem is exposed to soil. For sexual reproduction, kudzu is entirely dependent on pollinators.
Although kudzu prefers forest regrowth and edge habitats
with high sun exposure, the plant can survive in full sun or partial shade. These attributes of kudzu made it attractive as an ornamental plant for shading porches in the Southeastern United States
, but they facilitated the growth of kudzu as it became a “structural parasite” of the southern states, enveloping entire structures when untreated and often referred to as “the vine that ate the south”.
The word "kudzu" is a mispronunciation
of the Japanese word for the plant, kuzu.
in Philadelphia. Kudzu was first introduced in the Southeastern United States in 1883 at the New Orleans Exposition. The vine was widely marketed in the Southeastern United States as an ornamental plant to be used to shade porches, and in the first half of the 20th century, kudzu was distributed as a high-protein content cattle fodder
and as a cover plant to prevent soil erosion. The Soil Erosion Service
recommended the use of kudzu to help control erosion of slopes which led to the government-aided distribution of 85 million seedlings and government-funded plantings of kudzu which paid $19.75 per hectare
. By 1946, it was estimated that 1.2 million hectares of kudzu had been planted. When boll weevil
infestations and the failure of cotton crops drove farmers to move from rural to urban districts, kudzu plantings were left unattended. The climate and environment of the Southeastern United States allowed the kudzu to grow virtually unchecked. In 1953 the United States Department of Agriculture
removed kudzu from a list of suggested cover plants and listed it as a weed in 1970. By 1997, the vine was placed on the “Federal Noxious Weed List”
. Today, kudzu is estimated to cover 3 million hectares of land in the southeastern United States, mostly in Alabama
, Georgia
, Florida
, and Mississippi
. It has been recorded in Nova Scotia
, Canada
, and in all five boroughs of New York City
.
In Japan, kudzu thrives in mountainous regions, ranging from the 44th parallel north
(the island of Hokkaido
) to the 30th parallel north
(the island of Kuchinoshima
) and many of the lowlands and the islands. In Korea, kudzu grows in areas where the temperature can drop to -30 degrees Celsius.
, in fertilizer, and in erosion
control, and the vines have been used for folk art
. In China, kudzu root is used in herbal remedies
, teas, and the treatment of alcohol related problems
. The efficacy of the treatment of alcohol related problems is currently under question, but experiments show promising results. In Japan, the kudzu root starch
(or kuzu root starch) extracted from kudzu roots is used in cooking and natural medicines, and it is used to make hay that sick animals will eat. The starch is used in Japanese cuisine
, and it is considered the “world’s greatest cooking starch”. Kudzu is also used as a food crop
in Java
, Sumatra
, and Malay
, and can be found in Puerto Rico
and South America
.
Other uses may include: paper products, food products, insect repellents (the smoke from burning leaves), honey, and methane production.
in 1876 for the purpose of controlling soil erosion in Pennsylvania
. When kudzu was first introduced in the southeast, it was initially used as an ornamental vine to shade homes. By the early 20th century, southerners began to use kudzu for purposes other than ornamentation and so kudzu began to come closer in contact with the land which, in turn, encouraged its spread throughout the southeast. In the 135 years since its introduction, kudzu has spread over three million hectares (ha)
of the southern United States, and continues to ‘consume’ the south at an estimated rate of 50,000 ha/year, destroying power lines, buildings, and native vegetation in its path. In the United States, kudzu is extensively reported in Alabama
, Arkansas
, Washington, D.C.
, Delaware
, Florida
, Georgia
, Illinois
, Indiana
, Kentucky
, Maryland
, Missouri
, Mississippi
, North Carolina
, North Dakota
, New Jersey
, Oregon
, Ohio
, Pennsylvania
, South Carolina
, Tennessee
, Texas
, Virginia
, and West Virginia
. Of these states, three in the southeast have the heaviest infestations: Georgia, Alabama, and Mississippi.
in this region that is not found in other regions of the United States. Kudzu and other invasive weeds pose a significant threat to the biodiversity in the southeast. They reduce the environment to impoverished “vine barrens”. The fast growth and high competitive ability is achieved through several key features of kudzu that are detailed below.
Kudzu is a very stress-tolerant plant. Kudzu is drought tolerant
and only the above ground portions of the plant are damaged by frost. Kudzu also forms symbiotic relationships
with nitrogen-fixing bacteria
to convert atmospheric nitrogen (N2)
into ammonium
which can be used by surrounding plants. Now the dominant nitrogen-fixing plant in the eastern United States, kudzu fixes an estimated 235 kg of nitrogen per hectare per year, which is an order of magnitude higher than the rates of native species. This ability allows it to flourish in nitrogen-poor sites where other plants are unable to grow. In the absence of other plants, nitrogen then builds up in the soil, allowing the maintenance of large leaf areas and high photosynthetic rates
.
While little research has been conducted on the impacts of plant invasion on atmospheric conditions, a study conducted at Stony Brook University in New York
shows that kudzu has increased the concentration of atmospheric NOx
in the eastern United States, which causes a 2 ppb
increase in tropospheric ozone
during high temperature events in addition to soil acidification
, aluminum mobilization
, and leaching of NO3-
into aquatic ecosystem
s.
Once established in a habitat, kudzu is able to grow very quickly. Kudzu can grow up to 60 feet per season, or about one foot per day. Kudzu is also able to allocate large portions of carbon
to root growth, allowing it to acquire sufficient nutrients for rapid growth and to spread clonally
. Primary kudzu roots can weigh over 180 kg, grow to 0.18 m in diameter, and penetrate soil at a rate of 0.03 m in depth per day. Kudzu can also root wherever stems make contact with soil, allowing vines to grow in all directions. Once rooted, most stems lose connection with each other within one year, allowing each stem to become a physiologically independent individual, and requiring that all stems be treated or removed in order to eliminate a population.
In addition to its abilities to obtain nutrients and spread quickly, kudzu leaves have paraheliotropic
movements, meaning that they move in response to the movement of the sun in order to maximize photosynthetic productivity
. Kudzu is also a ‘structural parasite
,’ meaning that, rather than supporting itself, it grows on top of other plants and buildings to reach light. Its ability to reproduce and spread quickly allows it to quickly cover shrubs, trees, and forests, where it blocks the sun’s rays from the plants below it, decreasing or completely eliminating their photosynthetic productivity.
. In addition, it takes about $5,000 per ha per year to control kudzu. For power companies, it costs about $1.5 million per year to repair damage to power lines.
Kudzu management is of great concern in the management of national parks
in the southeast such as Vicksburg National Military Park
, Chickamauga and Chattanooga National Military Park
, and Great Smoky Mountains National Park
. In Vicksburg, kudzu has invaded 76 of the 800 total ha of the park and threatens to diminish the historical value of the park.
. These include mechanical, chemical, and biological methods.
and Triclopyr
and the most effective are Picloram
and Tebuthiuron
. However, chemical treatments are expensive, and killing off the plant completely requires large amounts of herbicides (40-80 gallons per acre). Herbicides are found to be most effective when they are used during the typical growing season, June–October, and when used for successive years. One case study saw a significant decrease in the growth of kudzu after just two years, whereas another study required the use of the herbicide for up to ten years.
Another form of chemical removal other than herbicides is soil solarization
. Soil solarization is a thermal (heat) method that utilizes solar-enhanced heating of the soil to kill the root system of the plant, thereby avoiding the use of pesticides and other more dangerous (fire-based) means to control the plant. Soil solarization affects the micronutrients and macronutrients in the soil. The most prominent effect of this method of control is the increase in potassium
(K). The higher level of K in all soils undergoing solarization demonstrates the successful release of K from decomposing kudzu plant tissues. Such a rise in K levels by solarization is important for soils in the Southeastern United States that tend to be highly weathered and generally have low K contents.
, insect herbivory, and insect seed predation
occur in high levels in field populations of kudzu. Seed predation is quite prevalent, with up to 81% of seeds incurring damage in populations studied in North Carolina. A different survey found twenty-five different species of insect feeding on the kudzu. From this survey, several leaf-feeding beetles and sawflies that have no other known hosts were identified. A separate study also found two weevils that attacked the stems of kudzu and eight beetles that complete larval development in the kudzu roots. When evaluations of potential control agents are made, the range of the control agents must be taken into account. Organisms that feed on kudzu will often feed on similar non-target species that are important in agriculture such as soybeans and hog-peanuts
. Potential control agents have to be rejected if they are shown in lab and field tests to feed on these non-target plants.
Of the diseases that have been identified as potential biological control agents, the fungal pathogen Myrothecium verrucaria
has been shown to be very promising. Disease development is very high at around 30 to 40 degrees Celsius which matches field conditions. In addition, the fungus does not spread outside of areas where it is applied. However, one major drawback of this biological control agent is that it is highly toxic to mammals so extreme care would have to be taken in handling this organism. Other pathogens have been tested as potential biological control agents but have proven to be ineffective.
Kudzu
Kudzu 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, . It is a weed that climbs over trees or shrubs and grows so...
is a serious invasive plant in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. It has been spreading in the southern U.S. at the rate of 150000 acres (60,702.9 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.
Description
KudzuKudzu
Kudzu 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, . It is a weed that climbs over trees or shrubs and grows so...
(Pueraria montana
Pueraria montana
Pueraria montana is a species of plant in the botanical family Fabaceae. At least three sub-species are known. It is closely related to other species in the genus Pueraria and the common name kudzu is used for all of these species and hybrids between them...
) is a perennial
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
vine native to Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, primarily subtropical
Subtropics
The subtropics are the geographical and climatical zone of the Earth immediately north and south of the tropical zone, which is bounded by the Tropic of Cancer and the Tropic of Capricorn, at latitudes 23.5°N and 23.5°S...
and temperate regions of China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, and Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...
, with trifoliate
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
leaves composed of three leaflet
Leaflet
A leaflet in botany is a part of a compound leaf. A leaflet may resemble an entire leaf, but it is not borne on a stem as a leaf is, but rather on a vein of the whole leaf. Compound leaves are common in many plant families...
s. Each leaflet is large and ovate
Oval
An oval is any curve resembling an egg or an ellipse, such as a Cassini oval. The term does not have a precise mathematical definition except in one area oval , but it may also refer to:* A sporting arena of oval shape** a cricket field...
with two to three lobe
Lobe
Lobe may refer to:* Lobe * Lobation, a characteristic of the nucleus of certain biological cells* Glacial lobe, a lobe-shaped glacier* Sidelobe, an identifiable segment of an antenna radiation pattern...
s each and hair on the underside. The leaves have the ability to fix atmospheric nitrogen
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...
, which can supply up to 95% of leaf nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
to the plant in poor soils. Along the vines are nodes
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
, points at which stems or tendril
Tendril
In botany, a tendril is a specialized stem, leaf or petiole with a threadlike shape that is used by climbing plants for support, attachment and cellular invasion by parasitic plants, generally by twining around suitable hosts. They do not have a lamina or blade, but they can photosynthesize...
s can propagate to increase support and attach to structures. As a twining vine
Vine
A vine in the narrowest sense is the grapevine , but more generally it can refer to any plant with a growth habit of trailing or scandent, that is to say climbing, stems or runners...
, kudzu uses stems
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
or tendrils that can extend from any node on the vine to attach to and climb most surfaces. In addition, the nodes of the kudzu vine have the ability to root when exposed to soil, further anchoring the vine to the ground. The roots are tuberous and are high in starch and water content, and the twining of the plant allows for less carbon concentration in the construction of woody stems and greater concentration in roots, which aids root growth. The roots can account for up to 40% of total plant biomass.
Kudzu’s primary method of reproduction is asexual
Asexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
vegetative spread (cloning)
Vegetative reproduction
Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new individuals arise without production of seeds or spores...
which is aided by the ability to root wherever a stem is exposed to soil. For sexual reproduction, kudzu is entirely dependent on pollinators.
Although kudzu prefers forest regrowth and edge habitats
Edge effect
The edge effect in ecology is the effect of the juxtaposition or placing side by side of contrasting environments on an ecosystem.This term is commonly used in conjunction with the boundary between natural habitats, especially forests, and disturbed or developed land. Edge effects are especially...
with high sun exposure, the plant can survive in full sun or partial shade. These attributes of kudzu made it attractive as an ornamental plant for shading porches in the Southeastern United States
Southeastern United States
The Southeastern United States, colloquially referred to as the Southeast, is the eastern portion of the Southern United States. It is one of the most populous regions in the United States of America....
, but they facilitated the growth of kudzu as it became a “structural parasite” of the southern states, enveloping entire structures when untreated and often referred to as “the vine that ate the south”.
The word "kudzu" is a mispronunciation
Anglicisation
Anglicisation, or anglicization , is the process of converting verbal or written elements of any other language into a form that is more comprehensible to an English speaker, or, more generally, of altering something such that it becomes English in form or character.The term most often refers to...
of the Japanese word for the plant, kuzu.
History
The kudzu plant was introduced to the United States in 1876 at the Centennial ExpositionCentennial Exposition
The Centennial International Exhibition of 1876, the first official World's Fair in the United States, was held in Philadelphia, Pennsylvania, from May 10 to November 10, 1876, to celebrate the 100th anniversary of the signing of the Declaration of Independence in Philadelphia. It was officially...
in Philadelphia. Kudzu was first introduced in the Southeastern United States in 1883 at the New Orleans Exposition. The vine was widely marketed in the Southeastern United States as an ornamental plant to be used to shade porches, and in the first half of the 20th century, kudzu was distributed as a high-protein content cattle fodder
Fodder
Fodder or animal feed is any agricultural foodstuff used specifically to feed domesticated livestock such as cattle, goats, sheep, horses, chickens and pigs. Most animal feed is from plants but some is of animal origin...
and as a cover plant to prevent soil erosion. The Soil Erosion Service
Natural Resources Conservation Service
The Natural Resources Conservation Service , formerly known as the Soil Conservation Service , is an agency of the United States Department of Agriculture that provides technical assistance to farmers and other private landowners and managers.Its name was changed in 1994 during the Presidency of...
recommended the use of kudzu to help control erosion of slopes which led to the government-aided distribution of 85 million seedlings and government-funded plantings of kudzu which paid $19.75 per hectare
Hectare
The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...
. By 1946, it was estimated that 1.2 million hectares of kudzu had been planted. When boll weevil
Boll weevil
The boll weevil is a beetle measuring an average length of six millimeters, which feeds on cotton buds and flowers. Thought to be native to Central America, it migrated into the United States from Mexico in the late 19th century and had infested all U.S. cotton-growing areas by the 1920s,...
infestations and the failure of cotton crops drove farmers to move from rural to urban districts, kudzu plantings were left unattended. The climate and environment of the Southeastern United States allowed the kudzu to grow virtually unchecked. In 1953 the United States Department of Agriculture
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
removed kudzu from a list of suggested cover plants and listed it as a weed in 1970. By 1997, the vine was placed on the “Federal Noxious Weed List”
Federal Noxious Weed Act of 1974
The Federal Noxious Weed Act of 1974 established a federal program to control the spread of noxious weeds. The United States Secretary of Agriculture was given the authority to declare plants "Noxious Weeds", and limit the interstate spread of such plants without a permit...
. Today, kudzu is estimated to cover 3 million hectares of land in the southeastern United States, mostly in Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
, Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
, Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, and Mississippi
Mississippi
Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...
. It has been recorded in Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, and in all five boroughs of New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
.
Native behavior
Kudzu is believed to have originated in China, where the ecosystem (primarily the tendency of kudzu to experience above-ground die back over winter) kept the vine from becoming a nuisance, and it is thought to have been introduced to Japan and likely Korea.In Japan, kudzu thrives in mountainous regions, ranging from the 44th parallel north
44th parallel north
The 44th parallel north is a circle of latitude that is 44 degrees north of the Earth's equatorial plane. It crosses Europe, the Mediterranean Sea, Asia, the Pacific Ocean, North America, and the Atlantic Ocean....
(the island of Hokkaido
Hokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...
) to the 30th parallel north
30th parallel north
The 30th parallel north is a circle of latitude that is 30 degrees north of the Earth's equatorial plane. It stands one-third of the way between the equator and the North Pole and crosses Africa, Asia, the Pacific Ocean, North America and the Atlantic Ocean....
(the island of Kuchinoshima
Kuchinoshima
is a volcanic island located in the Tokara Islands, part of the Nansei Islands, Japan. It is one of the islands in Toshima village. The island had 140 inhabitants as of 2004....
) and many of the lowlands and the islands. In Korea, kudzu grows in areas where the temperature can drop to -30 degrees Celsius.
Uses and cultivation
In the United States, kudzu has been used as livestock feedFodder
Fodder or animal feed is any agricultural foodstuff used specifically to feed domesticated livestock such as cattle, goats, sheep, horses, chickens and pigs. Most animal feed is from plants but some is of animal origin...
, in fertilizer, and in erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
control, and the vines have been used for folk art
Folk art
Folk art encompasses art produced from an indigenous culture or by peasants or other laboring tradespeople. In contrast to fine art, folk art is primarily utilitarian and decorative rather than purely aesthetic....
. In China, kudzu root is used in herbal remedies
Herbalism
Herbalism is a traditional medicinal or folk medicine practice based on the use of plants and plant extracts. Herbalism is also known as botanical medicine, medical herbalism, herbal medicine, herbology, herblore, and phytotherapy...
, teas, and the treatment of alcohol related problems
Alcoholism
Alcoholism is a broad term for problems with alcohol, and is generally used to mean compulsive and uncontrolled consumption of alcoholic beverages, usually to the detriment of the drinker's health, personal relationships, and social standing...
. The efficacy of the treatment of alcohol related problems is currently under question, but experiments show promising results. In Japan, the kudzu root starch
Kuzuko
is a starch powder made from the root of the kudzu plant.It is traditionally used in Japanese cuisine to thicken sauces and jellies, to make various noodlelike foods, and to make chilled desserts.Dishes that use kuzuko include:...
(or kuzu root starch) extracted from kudzu roots is used in cooking and natural medicines, and it is used to make hay that sick animals will eat. The starch is used in Japanese cuisine
Japanese cuisine
Japanese cuisine has developed over the centuries as a result of many political and social changes throughout Japan. The cuisine eventually changed with the advent of the Medieval age which ushered in a shedding of elitism with the age of shogun rule...
, and it is considered the “world’s greatest cooking starch”. Kudzu is also used as a food crop
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
in Java
Java
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...
, Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
, and Malay
Malay language
Malay is a major language of the Austronesian family. It is the official language of Malaysia , Indonesia , Brunei and Singapore...
, and can be found in Puerto Rico
Puerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
.
Other uses may include: paper products, food products, insect repellents (the smoke from burning leaves), honey, and methane production.
Ecology in and effect on new communities
New communities
Kudzu was intentionally introduced to North America by the Soil Erosion Service and Civilian Conservation CorpCivilian Conservation Corps
The Civilian Conservation Corps was a public work relief program that operated from 1933 to 1942 in the United States for unemployed, unmarried men from relief families, ages 18–25. A part of the New Deal of President Franklin D...
in 1876 for the purpose of controlling soil erosion in Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
. When kudzu was first introduced in the southeast, it was initially used as an ornamental vine to shade homes. By the early 20th century, southerners began to use kudzu for purposes other than ornamentation and so kudzu began to come closer in contact with the land which, in turn, encouraged its spread throughout the southeast. In the 135 years since its introduction, kudzu has spread over three million hectares (ha)
Hectare
The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...
of the southern United States, and continues to ‘consume’ the south at an estimated rate of 50,000 ha/year, destroying power lines, buildings, and native vegetation in its path. In the United States, kudzu is extensively reported in Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
, Arkansas
Arkansas
Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
, Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
, Delaware
Delaware
Delaware is a U.S. state located on the Atlantic Coast in the Mid-Atlantic region of the United States. It is bordered to the south and west by Maryland, and to the north by Pennsylvania...
, Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
, Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
, Indiana
Indiana
Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...
, Kentucky
Kentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...
, Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
, Missouri
Missouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
, Mississippi
Mississippi
Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...
, North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
, North Dakota
North Dakota
North Dakota is a state located in the Midwestern region of the United States of America, along the Canadian border. The state is bordered by Canada to the north, Minnesota to the east, South Dakota to the south and Montana to the west. North Dakota is the 19th-largest state by area in the U.S....
, New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
, Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
, Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
, Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
, South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
, Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...
, Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
, Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
, and West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...
. Of these states, three in the southeast have the heaviest infestations: Georgia, Alabama, and Mississippi.
Ecological relationships
Kudzu kills or damages other plants by smothering them under a blanket of leaves, encompassing tree trunks, breaking branches, or even uprooting entire trees. Kudzu’s ability to grow quickly, survive in areas of low nitrogen availability, and acquire resources quickly allows it to out-compete native species. Of the plants that can successfully compete with kudzu, many are other invasive species such as the Chinese privet and the Japanese honeysuckle. In the southeast, the spread of kudzu is especially troublesome because of the high level of biodiversityBiodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
in this region that is not found in other regions of the United States. Kudzu and other invasive weeds pose a significant threat to the biodiversity in the southeast. They reduce the environment to impoverished “vine barrens”. The fast growth and high competitive ability is achieved through several key features of kudzu that are detailed below.
Kudzu is a very stress-tolerant plant. Kudzu is drought tolerant
Drought tolerance
Drought tolerance refers to the degree to which a plant is adapted to arid or drought conditions. Desiccation tolerance is an extreme degree of drought tolerance...
and only the above ground portions of the plant are damaged by frost. Kudzu also forms symbiotic relationships
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
with nitrogen-fixing bacteria
Diazotroph
Diazotrophs are bacteria and archaea that fix atmospheric nitrogen gas into a more usable form such as ammonia.A diazotroph is an organism that is able to grow without external sources of fixed nitrogen. Examples of organisms that do this are rhizobia and Frankia and Azospirillum. All diazotrophs...
to convert atmospheric nitrogen (N2)
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
into ammonium
Ammonium
The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...
which can be used by surrounding plants. Now the dominant nitrogen-fixing plant in the eastern United States, kudzu fixes an estimated 235 kg of nitrogen per hectare per year, which is an order of magnitude higher than the rates of native species. This ability allows it to flourish in nitrogen-poor sites where other plants are unable to grow. In the absence of other plants, nitrogen then builds up in the soil, allowing the maintenance of large leaf areas and high photosynthetic rates
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
.
While little research has been conducted on the impacts of plant invasion on atmospheric conditions, a study conducted at Stony Brook University in New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
shows that kudzu has increased the concentration of atmospheric NOx
NOx
NOx is a generic term for the mono-nitrogen oxides NO and NO2 . They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures...
in the eastern United States, which causes a 2 ppb
Parts-per notation
In science and engineering, the parts-per notation is a set of pseudo units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement...
increase in tropospheric ozone
Tropospheric ozone
Ozone is a constituent of the troposphere . Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the atmosphere by day and by night...
during high temperature events in addition to soil acidification
Soil acidification
Soil acidification is the buildup of hydrogen cations, also called protons, reducing the soil pH. This happens when a proton donor is added to the soil. The donor can be an acid, such as nitric acid and sulfuric acid . It can also be a compound such as aluminium sulfate, which reacts in the soil to...
, aluminum mobilization
Podzolization
Podzolization is the comprehensive name for the process of mobilization and precipitation of dissolved organic matter, together with aluminum Al and iron Fe as they are leaching down from the A and E horizons to the B horizon . Through this process the overlying eluvial horizons are getting bleached...
, and leaching of NO3-
Nitrate
The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...
into aquatic ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
s.
Once established in a habitat, kudzu is able to grow very quickly. Kudzu can grow up to 60 feet per season, or about one foot per day. Kudzu is also able to allocate large portions of carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
to root growth, allowing it to acquire sufficient nutrients for rapid growth and to spread clonally
Clonal colony
A clonal colony or genet is a group of genetically identical individuals that have grown in a given location, all originating vegetatively from a single ancestor. In plants, an individual in such a population is referred to as a ramet...
. Primary kudzu roots can weigh over 180 kg, grow to 0.18 m in diameter, and penetrate soil at a rate of 0.03 m in depth per day. Kudzu can also root wherever stems make contact with soil, allowing vines to grow in all directions. Once rooted, most stems lose connection with each other within one year, allowing each stem to become a physiologically independent individual, and requiring that all stems be treated or removed in order to eliminate a population.
In addition to its abilities to obtain nutrients and spread quickly, kudzu leaves have paraheliotropic
Heliotropism
Heliotropism is the diurnal motion of plant parts in response to the direction of the sun.It is found in some members of family Malvacea e.g Malva or Lavetara...
movements, meaning that they move in response to the movement of the sun in order to maximize photosynthetic productivity
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
. Kudzu is also a ‘structural parasite
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
,’ meaning that, rather than supporting itself, it grows on top of other plants and buildings to reach light. Its ability to reproduce and spread quickly allows it to quickly cover shrubs, trees, and forests, where it blocks the sun’s rays from the plants below it, decreasing or completely eliminating their photosynthetic productivity.
Economic and cultural impact
The economic impact of kudzu in the United States is estimated at $100–500 million lost per year in forest productivityPrimary production
400px|thumb|Global oceanic and terrestrial photoautotroph abundance, from September [[1997]] to August 2000. As an estimate of autotroph biomass, it is only a rough indicator of primary production potential, and not an actual estimate of it...
. In addition, it takes about $5,000 per ha per year to control kudzu. For power companies, it costs about $1.5 million per year to repair damage to power lines.
Kudzu management is of great concern in the management of national parks
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
in the southeast such as Vicksburg National Military Park
Vicksburg National Military Park
Vicksburg National Military Park preserves the site of the American Civil War Battle of Vicksburg, waged from May 18 to July 4, 1863. The park, in Vicksburg, Mississippi, and Delta, Louisiana, also commemorates the greater Vicksburg Campaign, which preceded the battle. Reconstructed forts and...
, Chickamauga and Chattanooga National Military Park
Chickamauga and Chattanooga National Military Park
Chickamauga and Chattanooga National Military Park, located in northern Georgia and eastern Tennessee, preserves the sites of two major battles of the American Civil War: the Battle of Chickamauga and the Chattanooga Campaign.-History:...
, and Great Smoky Mountains National Park
Great Smoky Mountains National Park
Great Smoky Mountains National Park is a United States National Park and UNESCO World Heritage Site that straddles the ridgeline of the Great Smoky Mountains, part of the Blue Ridge Mountains, which are a division of the larger Appalachian Mountain chain. The border between Tennessee and North...
. In Vicksburg, kudzu has invaded 76 of the 800 total ha of the park and threatens to diminish the historical value of the park.
Control and removal methods
There are several methods for controlling kudzu growth that are used in the Southeastern United StatesSoutheastern United States
The Southeastern United States, colloquially referred to as the Southeast, is the eastern portion of the Southern United States. It is one of the most populous regions in the United States of America....
. These include mechanical, chemical, and biological methods.
Mechanical
Most mechanical means of kudzu removal practiced in the southeastern United States involve mowing the vine or cutting it back. These methods, though more effective than herbicides, are more time consuming. Vines must be mowed down just above ground level every month or two during the growing season in order to prevent the them from growing back. When using this method of kudzu control, all of the plant material must be removed and/or destroyed (burned) to prevent the vines from taking root and re-growing. Another method of mechanical removal is to remove the crown of the plant. This part must also be destroyed to prevent re-implantation.Chemical
A different, and sometimes less time consuming option for the control of kudzu is chemical treatment with herbicides. Some common herbicides used are TordonPicloram
Picloram is a systemic herbicide used for general woody plant control, sold under the trade names Tordon and Grazon. It also controls a wide range of broad-leaved weeds, but most grasses are resistant...
and Triclopyr
Triclopyr
Triclopyr is a systemic, foliar herbicide in the pyridine group. It is used to control broadleaf weeds while leaving grasses and conifers unaffected....
and the most effective are Picloram
Picloram
Picloram is a systemic herbicide used for general woody plant control, sold under the trade names Tordon and Grazon. It also controls a wide range of broad-leaved weeds, but most grasses are resistant...
and Tebuthiuron
Tebuthiuron
Tebuthiuron is a nonselective broad spectrum herbicide of the urea class. It is used in a number of herbicides manufactured by Dow AgroSciences, and is sold under several trade names, depending on the formulation. It is used to control weeds, woody and herbaceous plants, and sugar cane...
. However, chemical treatments are expensive, and killing off the plant completely requires large amounts of herbicides (40-80 gallons per acre). Herbicides are found to be most effective when they are used during the typical growing season, June–October, and when used for successive years. One case study saw a significant decrease in the growth of kudzu after just two years, whereas another study required the use of the herbicide for up to ten years.
Another form of chemical removal other than herbicides is soil solarization
Soil solarization
Soil solarization is an environmentally friendly method of using solar power for controlling disease agents in the soil by mulching the soil and covering it with tarp, usually with a transparent polyethylene cover, to trap solar energy....
. Soil solarization is a thermal (heat) method that utilizes solar-enhanced heating of the soil to kill the root system of the plant, thereby avoiding the use of pesticides and other more dangerous (fire-based) means to control the plant. Soil solarization affects the micronutrients and macronutrients in the soil. The most prominent effect of this method of control is the increase in potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
(K). The higher level of K in all soils undergoing solarization demonstrates the successful release of K from decomposing kudzu plant tissues. Such a rise in K levels by solarization is important for soils in the Southeastern United States that tend to be highly weathered and generally have low K contents.
Biological
As chemical treatments are often ineffective for long term control and mechanical removal is likewise difficult and costly for long-term control, kudzu makes a good candidate for biological control. There are several biological means that are already in place and more that may be implemented to control the growth of kudzu. Bacterial blightsBlight
Blight refers to a specific symptom affecting plants in response to infection by a pathogenic organism. It is simply a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. Accordingly, many diseases that primarily exhibit this...
, insect herbivory, and insect seed predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
occur in high levels in field populations of kudzu. Seed predation is quite prevalent, with up to 81% of seeds incurring damage in populations studied in North Carolina. A different survey found twenty-five different species of insect feeding on the kudzu. From this survey, several leaf-feeding beetles and sawflies that have no other known hosts were identified. A separate study also found two weevils that attacked the stems of kudzu and eight beetles that complete larval development in the kudzu roots. When evaluations of potential control agents are made, the range of the control agents must be taken into account. Organisms that feed on kudzu will often feed on similar non-target species that are important in agriculture such as soybeans and hog-peanuts
Amphicarpaea bracteata
Amphicarpaea bracteata is an annual to perennial vine in the legume family, native to woodland, thickets, and moist slopes in eastern North America.-Description:Leaves have three leaflets and are held alternately on twining stems....
. Potential control agents have to be rejected if they are shown in lab and field tests to feed on these non-target plants.
Of the diseases that have been identified as potential biological control agents, the fungal pathogen Myrothecium verrucaria
Myrothecium verrucaria
Myrothecium verrucaria is a plant pathogen. It is common throughout the world, often found on materials such as paper, textiles, canvas and cotton. It is a highly potent cellulose decomposer....
has been shown to be very promising. Disease development is very high at around 30 to 40 degrees Celsius which matches field conditions. In addition, the fungus does not spread outside of areas where it is applied. However, one major drawback of this biological control agent is that it is highly toxic to mammals so extreme care would have to be taken in handling this organism. Other pathogens have been tested as potential biological control agents but have proven to be ineffective.
See also
- Invasive species in the United StatesInvasive species in the United StatesInvasive species are a significant threat to many native habitats and species of the United States and a significant cost to agriculture, forestry, and recreation. The term "invasive species" can refer to introduced or naturalized species, feral species, or introduced diseases...
- Environmental issues in the United StatesEnvironmental issues in the United StatesAs with many other countries there are a number of environmental issues in the United States.-Climate change:The United States is the second largest emitter, after China, of carbon dioxide from the burning of fossil fuels. The energy policy of the United States is widely debated; many call on the...