Wednesday, December 9, 2009

What can we do about a problem like kudzu?

When I was 17, I moved to Atlanta to attend university. I arrived on a hot, muggy afternoon, eager for my first glimpse of my new home. Driving north into the city from the airport, I noticed that the interstate had lush greenery on either side, which surprised me for such a large city. But as I looked closer, I noticed that it was also strangely uniform. I couldn't detect any individual trees or shrubs beneath a thick carpet of identical leaves. I didn't realize it at the time, but I was looking at kudzu, also known as the "vine that ate the South." My view out the window was a tragic example of the ecological devastation wreaked by an out of control invasive species.

According to Richard Blaustein, kudzu was first introduced to the United States in the late nineteenth century as an ornamental plant, prized for its wide, shady leaves. At the time, it was planted with trellis supports that helped to inhibit normal reproduction, but by the early twentieth century it was being planted as an inexpensive feed for livestock and to produce hay which was then transported on the railroad. However, the major culprit in the spread of kudzu was the United States government:
In the 1930s, massive soil erosion on Southern farmlands compounded the local impact of the Great Depression, seriously threatening the region's agricultural base. To bring the erosion under control, the federal government launched a massive promotional campaign for Kudzu. Throughout the 1930s and 1940s, the Soil Erosion Service and its successor, the Soil Conservation Service, touted Kudzu as the remedy to the South's soil problems. In a little more than a decade, these agencies provided "about 84 million Kudzu southern landowners for erosion control and land revitalization..[and it] offered up to $20 per ha as an incentive for farmers to plant their land in Kudzu" (Miller, pers. comm.). The acreage planted in Kudzu rose from an estimated 4,000ha in 1934 to 1.2 million ha by 1946 (Blaustein, 57).

Farmers soon noticed that the plant was out of control, as it began to rapidly cover its surroundings with its verdant foliage. In its native climate, it is fairly non-threatening, but the warm and humid climatic conditions in the American Southeast cause it to grow much more quickly – at a rate of up to 30 cm a day. Its semi-woody vines are held in place by roots more than 18 cm in diameter and 180 cm in length, and it can easily regrow unless its crowns are completely destroyed. Telephone poles, abandoned buildings, and most importantly, other plants were soon completely covered. The United States Department of Agriculture (USDA) removed kudzu from its list of allowable cover plants in 1953, but it was not until 1997 that kudzu was finally listed as a "noxious weed" under the Federal Noxious Weed Law. By this time, kudzu covered millions of acres of land in the American Southeast (Blaustein, 56-57).

American states where kudzu has been reported invasive

Kudzu is a classic example of an invasive species - it is non-native to the local ecology and causes significant environmental and economic damage to the ecosystem (Study Guide, 69). Part of the pea family, it is a climbing perennial vine that is native to China and Japan that spreads through vine growth, rhizomes, and seeds.

The costs of kudzu are high - in many areas, it's extremely difficult to tell from looking at the foliage that anything else lives there. The local ecosystem has been completely altered. This ecological impact is particularly disheartening because the American south-east serves as the last bastion of many species displaced from northern latitudes by advancing glaciers during the last ice age. Kudzu inhibits natural processes of tree renewal by blocking its competitors' access to sunlight as it covers and slowly crushes them beneath its weight. By doing so, kudzu is able to eliminate its indigenous plant species competition as it spreads through forests, such as young hardwoods and other native plant life. Wildlife which depends on those plants for habitat are also affected, some of which were rare wetlands species which have now been completely eliminated (Blaustein, 56;Study Guide, 72). As a result, richly diverse forest wetlands ecosystems have been replaced by a deceptively lush yet ecologically barren monoculture of vines.

There are human costs as well, such as costly removal when kudzu grows over railroad tracks, power lines, and envelopes buildings. The vine has also been known to act as a host for soybean rust, which can have devastating economic consequences for farmers. There is even an historic cost - the Southern landscape is irrevocably different from what it looked like during the antebellum period, or before the Cherokee were forced to leave Georgia on the Trail of Tears. The first introduction of kudzu occurred soon after the Civil War, so it is difficult to know how many local species were destroyed before kudzu's deleterious effects were realized.

This isn't the landscape Mark Twain had in mind when he wrote about Huckleberry Finn's adventures on the river.

Since kudzu is so entrenched, eradication is now an impossibility, even at an astronomical cost. Attempts to remove kudzu with traditional herbicides have had little effect and also destroyed wildlife. Application temporarily kills the leaves of the vines, but the crowns remain untouched and the plant regrows quickly, resulting in a net growth of kudzu by the following year. The study I reviewed suggested that systematic spraying might be successful as part of a yearly campaign, but it would not result in eradication (Davis 62-63). Using goats for grazing is more environmentally friendly and has had better results. The nimble-footed goats are able to easily reach areas that humans can't, and are quite thorough when eating (Emery). This method seems most useful in removing kudzu from important areas like railroad tracks and tunnels, because the use of the goats has limitations. For instance, goats are an unrealistic solution in urbanized areas such as Atlanta, and they are likely to eat other plant species as well. They are also unable to reach the tops of trees.

There is general agreement on kudzu's harmfulness, but many people also believe that kudzu can be useful to humans. National Geographic reports that there are cottage industries that use the vine for everything from baskets to dye, but such uses put little dent in the overall volume of kudzu. It also appears to have medicinal uses. Preliminary studies show that it can be used to treat alcoholism and to alleviate menopausal side effects. The latter could prove to be very important, as the former treatment of choice, Hormone Replacement Therapy, has fallen out of favour since being linked to breast cancer. Kudzu, if proven safe and effective, could be a powerful alternative.

Biofuel is another potential application of kudzu, but I do not believe it to be a good idea. Kudzu as a fuel source is not very efficient - it has an energy yield roughly equivalent to corn, putting it on the low end of the spectrum. Secondly, kudzu is one of the plants that grows faster in increased CO2 conditions (Sasek, 23). Biofuel is more efficient than traditional oil, but it still produces some emissions and it would be a tragedy to harvest kudzu for a task that will cause more of it to grow. Lastly, if using kudzu for biofuel does become popular, it is likely that corporations will try to plant kudzu in areas that are more easily harvested than rocky hillsides, resulting in more environmental degradation.

Although capitalizing on kudzu's presence is a good idea, none of the ideas listed would come close to eliminating kudzu. They are merely an attempt to cope with its prevalence. We should make use of kudzu where we can, but our best strategy is to try to mitigate its spread and the damage it causes, because it continues to spread. This year, kudzu was spotted in southern Ontario, an area where it was assumed that kudzu could not live because of its preference for mild winters. Scientists are currently trying to determine how to remove the plant quickly before it spreads into other parts of Canada. Let's hope they're successful.


Belokrinicev, Brenda, Editor. Environmental Studies 243 Study Guide: Environmental Change in a Global Context. 2007: Athabasca University.

Blaustein, Richard J. “Kudzu’s invasion into Southern United states life and culture.” In: McNeeley, J. A. ed. The Great Reshuffling: Human Dimensions of Invasive Species. 2001. IUCN, Gland, Switzerland and Cambridge, UK. The World Conservation Union: 55-62.

Coblentz, Bonnie. "Soybean rust battle takes look at kudzu." Mississippi Agricultural News. Mississippi State University: Office of Agricultural Communication. 1 May 2008. 30 November 2009.

Davis, D.E. and H.H. Funderburk, Jr. “Eradication of Kudzu.” Weeds. 12: 1 (1964): 62-63. 30 November 2009.

Emery, Theo. "In Tennessee, Goats Eat the ‘Vine That Ate the South’." New York Times. 5 June 2007. 30 November 2009.

"Got a drinking problem? Try kudzu." Associated Press: MSNBC. 17 May 2005. 30 November 2009.

Marshall, Jessica. "Kudzu Gets Kudos as a Potential Biofuel." Discovery News. 16 June 2008. 30 November 2009.

National Park Service. Distribution map of kudzu infestation. 2006. 30 November 2009.

Roach, John. 'Kudzu Entrepreneurs Find Gold in Green "Menace"'. National Geographic News. 22 April 2005. 30 November 2009.

Sasek, Thomas W. and Boyd R. Strain. "Effects of Carbon Dioxide Enrichment on the Expansion and Size of Kudzu (Pueraria lobata) Leaves." Weed Science 37:1 (1989): 23-28. 30 November 2009.

"Grapes, Soy And Kudzu Blunt Some Menopausal Side Effects." Science Daily. 14 August 2007. 30 November 2009.

Smith, Galen Parks. Image: Kudzu covered field near Port Gibson, Mississippi, USA. 14 August 2006. 30 November 2009.

"Smothering vine that snaps hydro poles now in Canada." Canadian Press: CTV News. 23 September 2009. 30 November 2009.

Tenuta, Albert and Terry Anderson. Image: Kudzu alongside stream.