Kudzu: The Guest That Just Won’t Leave

From USFS Southern Research Station

Posted on April 9, 2013 by zhoyle

 

Kudzu infestation in North Carolina. Photo by Barry Rice, courtesy of Bugwood.org.

Spring is right around the corner, and in the South, “all eyes… turn to kudzu… as it awakes,” says James Miller, research ecologist (emeritus) for the U.S. Forest Service Insects, Diseases, and Invasive Plants unit.
Introduced to United States at the 1876 Centennial Exposition in Philadelphia, kudzu was touted as a quick-growing ornamental vine with fragrant blossoms and broad leaves which provided abundant shade. At the turn of the century, the U.S. government promoted kudzu to help reduce soil erosion and provide an inexpensive forage crop for livestock in the South.

By 1946, some estimated that the vine covered over 3 million acres of land. Today, it’s estimated to occupy 7 million acres and covers 50,000 new acres each year! And that’s the problem: with an average growth rate of a foot per day, kudzu quickly establishes itself as a dominant plant, blocking out sunlight and obliterating other plants. It overtakes landscapes, creeps up telephone poles, and engulfs street signs and abandoned buildings.

So how do you get rid of such an imposing guest? Well, some are easier to usher out than others, but kudzu proves to be one of the hardest. Miller spent over 40 years studying invasive plant management, and he admits that “nothing eradicates it 100 percent.” Kudzu has no native predators and is resistant to the effects of cold weather. 

Early effort to control kudzu? Photo from USDA NRCS Archive, courtesy of Bugwood.org.

The most effective eradication and management options include livestock grazing or herbicides, but prescribed burning, disk harrowing, plastic sheeting, and mechanical removal techniques may also be used. Land owners and managers must choose an option that best fits the conditions in a given landscape. Further complicating the issue is the fact that successful eradication requires that “every kudzu plant in and around a patch must be killed or removed to prevent reoccupation,” says Miller. Thus, at some point, robust plants like fast growing pines, native shrubs, or perennial grasses must be established to overtop or suppress remaining kudzu to restore an area.

Recently, a new management option is being explored. An accidentally introduced insect has shown promise in the battle with kudzu. Entomologists Jim Hanula and Scott Horn—both with the Forest Service Southern Research Station (SRS) Insects, Diseases, and Invasive Plants unit—worked with Yanzhuo Zhang, a postdoctoral associate at the University of Georgia, to investigate the impact of the bean plataspid, aka “kudzu bug” (Megacopta cribraria), on the growth of kudzu. “We found that unprotected plots had 40 times the number of bugs than sprayed plots and a third less kudzu,” says Hanula. “We were actually surprised that this insect had such an impact in only one growing season.” 

Jim Miller with kudzu. Photo by Erwin Chambliss.

In 2010, SRS published A Field Guide for the Identification of Invasive Plants in Southern Forests. Miller, lead author of the guide, is one of the foremost authorities on invasive plants in the South; co-authors are SRS research technician Erwin Chambliss and Auburn University research fellow and extension specialist Nancy Lowenstein. The book provides information on accurate identification of the 56 nonnative plants and groups that are currently invading the forests of the 13 Southern States. It lists other nonnative plants of growing concern.

The information included in the guide is now available as a free application for iPhones, iPods, and iPads called Invasive Plants in Southern Forests.
Recommendations for prevention and control of these invasive species are provided in a companion booklet, “A Management Guide for Invasive Plants of Southern Forests,” which Miller co-authored with Steven Manning, president of Invasive Plant Control, Inc., and Stephen Enloe, Auburn University weed management extension specialist.—Maureen Merriman

For more information, email Jim Miller at jameshmiller@fs.fed.us.

Read an earlier CompassLive story about the kudzu bug research by Hanula and Horn.

Access the latest publications by SRS scientists.