Heather N. Kolich, ANR Agent, UGA Extension Forsyth County
Georgia has several problematic invasive plants, but kudzu seems to get the most attention. The vine is highly visible, covering banks, trees, and abandoned houses, whether you’re driving in the country or around town. The spread of kudzu has been an ecological concern in the southeastern U.S. for several decades.
Native to Asia, kudzu was a featured international plant of the 1876 Philadelphia Centennial Exposition. It appeared again at the 1883 New Orleans Exposition, showing off its attractive and fragrant flowers. Soon after, southerners began to import seeds for decorative plantings. During the early 1900s, farmers were urged – and paid – to plant kudzu for cattle forage, erosion control, and soil fertility improvement.
By 1946, farmers and the Civilian Conservation Corps had planted around 3 million acres of kudzu across the southern U.S. Although many plantings failed, those that succeeded enjoyed ideal growing conditions and a complete absence of diseases and pests that keep kudzu in check in its native countries. With post-WWII abandonment of farms, kudzu spread widely and fell from favor. The USDA removed it from the list of approved cover crops in 1953 and designated it a weed in 1970.
Unfortunately, kudzu wasn’t fazed by its fall from favor. In 2009, the Georgia Forestry Commission and the Forest Inventory and Analysis teams began tracking the spread of nonnative invasive plants in Georgia forest lands. In the first publication of the GFC “Dirty Dozen” worst invasive plant list, kudzu ranked third, claiming nearly 27,000 acres of Georgia land. It increased to over 42,000 acres in 2011, but by 2017 it hit a low of just under 31,000 acres before beginning to climb again. Kudzu also dropped to the 5th most invasive ranking as two other nonnative plants surged in spread.
Kudzu is very difficult to control. So what happened to knock it back by 11,000 acres between 2011 and 2017? In the fall of 2009, Georgia experienced the accidental introduction of Megacopta cribraria, commonly known as the kudzu bug. Another invasive species without predators to control it, kudzu bugs quickly spread outward from the North Georgia epicenter. By the end of 2011, kudzu bugs were confirmed in 125 Georgia counties, all counties in South Carolina, 58 counties in North Carolina, one county in Virginia, and eight in Alabama. In the process, they established themselves as a major pest of soybeans, causing significant yield and economic losses, and as a major nuisance pest that clusters on and overwinters in homes.
With far less media coverage, kudzu bugs also feasted on the abundance of kudzu in Georgia. The kudzu reduction honeymoon began to fizzle in 2013, however, when a parasitic wasp, native to Asia, began laying its eggs inside the eggs of kudzu bugs in Georgia. As the wasps spread to Alabama and Mississippi, researchers discovered a second natural predator, a fungus that kills adult kudzu bugs as they overwinter. By 2014, researchers were commenting on the declining number of kudzu bugs. By 2016, kudzu bug populations had declined dramatically, and in 2019, kudzu had gained back 2,000 acres of Georgia forest land.
Eradicating established kudzu is a laborious process that may take years of persistence. Kudzu is a perennial plant with vines that emerge from the crown of tubers. While vines can root at points where they contact the ground, kudzu does not root into trees that it climbs. Cutting the vine a few feet above ground will kill the foliage in trees. Follow vines back to the tuber and dig out and remove the crown, or cut into the crown and treat it with a herbicide containing glyphosate or triclopyr.