Background, Life History Kudzu (Pueraria montana) is a climbing, semi-woody, perennial vine of the legume family. Originally imported from Japan and China in the early 1900s, kudzu was utilized for ornamental purposes and as a forage crop for livestock in the southern United States. During the Great Depression, kudzu was heavily promoted for erosion control. In Missouri, kudzu was planted along highways to control erosion and as forage prior to 1970. Today it can be found in isolated populations within select counties primarily along highways. Kudzu grows well under a wide range of conditions and in most soil types, except for saturated soils. Preferred habitats are forest edges, abandoned fields, roadsides and disturbed areas, where sunlight is abundant. Kudzu grows best where winters are mild and summers are hot. Harsh winters can kill young stems, but root crowns will re-sprout. Kudzu stems are yellow-green with dense, erect, golden hairs and matted, silver hairs. As stems mature, they become ropelike, light gray to brown and hairless. Mature vines develop massive taproots able to penetrate up to 12 feet in depth. Leaves are alternate, with three broad leaflets up to 9 inches in length. Leaflets may be entirely or deeply two- or three-lobed with hairy margins. Fragrant purple flowers form in clusters from June to September. Only vines in full sun will flower. Flattened, hairy legume pods contain three to 10 oval seeds, few of which are viable. Kudzu reproduces primarily by vegetative means. Numerous individual vines trail and climb from a single large, ball-like central root crown. Vines in contact with the soil will root at the nodes to form a new root crown and new stems. New vines also sprout from rhizomes.

Impacts Once established, kudzu plants grow prolifically, with a single root crown containing up to 30 vines. Kudzu rampantly spreads to form dense mats over the ground, shrubs, mature trees and buildings, reaching more than 60 feet high. Kudzu kills or degrades other plants by smothering them under a solid blanket of leaves that allow little light to penetrate. It can girdle shrubs and trees, break branches and uproot entire trees under its weight. In the 1950s, the Agricultural Conservation Program removed kudzu from the list of species acceptable for use as an agricultural forage crop or soil stabilization plant. Congress listed kudzu as a Federal Noxious Weed in 1998. In 2014, the State of New York designated kudzu as a prohibited plant under the state’s Environmental Conservation Law.

Control: Typical mechanical treatments are not likely to be successful on kudzu. Therefore, few options remain except herbicide applications. Although herbicide applications can be conducted any time the vine is actively growing, foliar applications of clopyralid in the late summer or early fall when nutrients are being transported to the root system are one of the most effective treatments. In mature populations, aerial vines should be controlled first using cut-stump or basal-bark treatment methods. Basal-bark treatment can be done for smaller vines less than 2 inches in diameter by spraying two feet of vine near ground level with triclopyr mixed with an oil or diesel fuel. For cut-stem treatments, cut individual vines at ground level and apply herbicide to the cut stem. Effective herbicides include triclopyr, picloram plus 2,4-D, or glyphosate. Both methods can be utilized during the dormant season. Re-sprouting should be controlled with clopyralid or triclopyr applications to the foliage.

Identifying Kudzu:

fast-growing, climbing vines hairy vines and leaves large-lobed leaves are alternate and

trifoliate (consisting of three leaflets)

inconspicuous reddish purple flowers on climbing vines

brown, flattened, hairy seed pod with three to 10 seeds

Kudzu Range

Native Look-alikes: Large poison ivy (Toxicodendron radicans) leaves and vining stems look similar to kudzu, but kudzu stems and leaves are much more conspicuously hairy. Round-leafed beggar’s tick (Desmodium rotundifolium) and hog peanut (Amphicarpaea bracteata) might be confused with a young plant of kudzu, but these trailing legumes do not grow longer than a few feet.

Habitat and Ecology: Factors that help determine how invasive kudzu will be in any habitat appear to be climate (warmth and humidity are important factors, with greater colonization corresponding to warmer average annual temperatures and higher average humidity) and availability of light (with the vines climbing existing vegetation and hard vertical surfaces to reach additional light). It does not appear that the composition of the local native plant community

has much influence on kudzu invasiveness. Even undisturbed plant communities adjacent to an existing population of kudzu can be at risk. Typical kudzu habitat is usually open, disturbed areas (e.g. roadside ditches, rights-of-way, and abandoned fields). In such areas, kudzu can for huge monocultures with thousands of kudzu plants per acre.

Kudzu has a strong daily leaf orientation capability; by controlling the leaf position as it faces toward or away from the sun, kudzu can control sunlight intensity on the leaflets that are exposed. This can reduced leaf temperatures relative to native vegetation and minimize the amount of water lost from the plant by leaf surface transpiration during times of peak sunlight. This may also be a benefit below forest canopies where light is dim by increasing the surface area of leaves receiving sunlight. Leaves exposed to open sunlight may be able to maximize photosynthesis, store additional food in kudzu’s rhizomes, and have a competitive advantage over native vegetation. Kudzu accumulates and maintains substantial carbon reserves in large woody, tuberous roots, again giving it a competitive advantage. Trailing stems in open areas tend to die back in the winter. Vertically climbing vines develop thick bark and can reach diameters greater than 0.8 inch (2 cm), aiding in overwintering.

Kudzu vines can more easily grow around smaller vines such as honeysuckle (Lonicera spp.) than around bare tree trunks. This appears to aid the plant in the formation of lianas in forested areas. Once established, kudzu lianas compete with forest trees both for sunlight in the crown and for water and nutrients from the soil. The vines may directly damage colonized trees by strangulation. These physical traits of a kudzu liana significantly impact the ability of native trees to grow and reproduce, increasing the early mortality of native trees, and preventing the establishment of new trees or shrubs in the dim light below the colonized canopy.

Kudzu lianas can cause weakened trees to fall from the weight of the overgrowth of vines or by pulling down trees attached to the liana when one weak tree succumbs to the weight of ice freezing onto the tree and/or the vines. Kudzu thrives where the climate favors mild winters (40 - 60°F {4 -16°C}), summer temperatures rising above 80°F (27°C), greater than 40 inches (101 cm) precipitation, and a long growing season. Because of its underground root crowns, kudzu can escape fire damage. During the growing season, kudzu's underground root system can provide significant water to the foliage; the high water content stems and foliage are able to resist some fire damage that may kill nearby native plants. There is some indication (not yet definitively proven) that wildfire (or controlled burn) soil heating may promote kudzu seed germination by scarifying the seedcoat which would allow penetration by water to allow for germination.

Native Plant Community Impacts: A kudzu invasion can cause several different types of major impacts on native plant communities: it can crowd out natives species; it can out-compete native species; and it can physically crush native species. Since kudzu can fix nitrogen in its roots, it can thrive in soils too low in nitrogen to support robust growth of native vegetation, thereby outcompeting native plants for both nutrition and growing space, ultimately forming monospecific (single species dominant, in this case kudzu) plant communities. This significantly alters natural plant communities and the animals that rely on those natural communities for food and habitat. Areas of more than 100 acres (40 hectares) with 1 - 2 plants per square foot, or 40,000 to 85,000 plants per acre (107,000 to 215,000 plants per hectare) can be found in the American South. Kudzu’s rapid growth rate and its manner of growing over whatever it encounters in its path, can also overwhelm native plant communities resulting in monospecific stands of the vine.

As heavy infestations of kudzu can completely cover trees of almost any size, kudzu lianas can both fell trees from their extreme weight or nearly eliminate light availability within the forest canopy, weakening or killing shade-intolerant species, particularly pines. Once kudzu gains access to the forest canopy, the liana formed can spread faster and more aggressively through a forest.

Control Methods: Control of well-established colonies is challenging and can take 10 years or more. Total root eradication is needed but difficult with older stands. Strategies depend on whether the patch is in the open, draped over trees, near water, in young trees or under older trees. Patch evaluation during dormant periods is suggested to better identify major root locations, aid ease of walking, and to reveal hidden hazards such as gullies and fences.

Mechanical Repeated mowing or cutting is slow, but can be effective on younger patches if done several times per season for 3-4 years. Defoliating the plants weakens and will eventually starve them to death. Mowing is useful as a means of reducing biomass to prepare a site for subsequent foliar herbicide spraying. Cut vines may re-root and continue to grow, so dispose of them carefully. Grazing Kudzu is a high-quality forage that is eagerly consumed by livestock. Close grazing at a heavy stocking rate for several years can eliminate kudzu when 80% or more of the vegetative growth is continuously consumed.

Burning Prescribed fire can top-kill kudzu, but may not harm roots or root crowns – though it may kill seedlings. It can, however, prepare a site for later herbicide treatment by reducing biomass, revealing site hazards and facilitating the identification of root crowns for later treatment. Fire is known to stimulate germination of legumes by breaking down the hard seed coat. This may be used as a means of exhausting the seed bank as long as there is long-term commitment to monitoring and treatment. Use caution in situations where dead vines are draped over trees as there is risk of generating crown fires. Spring and fall burns can be effective in reducing biomass, while spring burns are most effective for seedling control.

Herbicide There are several treatment methods available: foliar, basal bark, cut stem and root crown. Consult websites, local chemical dealers, extension agents, foresters and other specialists familiar with kudzu control. Root control, patch age and location, and land use are the primary considerations when selecting herbicides for a particular site. All methods require follow-up treatments and long-term monitoring to ensure that all plants are killed. Herbicides can be broadcast or spot sprayed on foliage. Products with clopyralid are legume-specific, but other systemic herbicides can be effective. Adding a surfactant will increase absorption. Established stands can be treated by cutting stems at ground level and painting or spraying the stumps with glyphosate (20% active ingredient) or triclopyr (12.5% active ingredient) mixed with a bark penetrating oil. The un-cut bases of vines can be similarly treated. Late summer and throughout the dormant season are the best times for treatment. Large roots may become dormant for one or more years after chemicals are applied, and may eventually resprout. If treating kudzu near water or wetlands, use specially formulated products that are safe for use around water.

Some Cool History: Pueraria montana: Pueraria was named for Marc Nicolas Puerari, a 19th century Swiss botanist; montana means of the mountains. Kudzu comes from a Japanese word meaning vine. It originated in eastern Asia and was introduced as an ornamental at the 1876 U.S. Centennial Exposition in Philadelphia. Other virtues were soon discovered and by the 1920s kudzu was widely planted as a forage plant and in the 1930s was promoted for erosion control. Its invasive nature alarmed many, however, and by 1953 the USDA banned kudzu as a cover crop. Its large, starchy roots are edible and can be used as a thickener for cooking. Leaves can be eaten in a salad or cooked. Vines are used for baskets and paper-making. In China and Japan, ground kudzu root (called kuzu) has been a common ingredient in foods. Traditional Asian healers have long valued roots and flowers for treating colds, flu, high blood pressure, chest pain, allergies and a host of other ailments. Recent research indicates that a compound in the root may also increase blood flow to the heart and brain. Kudzu can serve as an alternate host for soybean rust.

For Additional Information: https://en.wikipedia.org/wiki/Kudzu_in_the_United_States (THIS ONE IS REALLY GOOD!!!)

www.invasivespeciesinfo.gov/plants/kudzu.shtml , http://www.na.fs.fed.us/spfo/invasiveplants/ , www.fs.fed.us/database/feis/plants/vine/puemonl/all.html , www.mdc.mo.gov/node/5524