On an October day in Knoxville, Jill Wells mixed a concoction of lye, oils, and leaves from the invasive kudzu vine in her kitchen to make kudzu-infused soap.
“Nothing says the south like kudzu, you know?” she joked.
Wells explained the kudzu soap was initially sold as a joke, with the vine being a ubiquitous problem in southern cities like Knoxville. Other residents have used the plant to make jelly, sauces and crafts.
“Anybody who likes to look up new crafts and really wants to get into making stuff, kudzu is an excellent thing,” said fiber artist Mandy Carris, standing in front of a table of homemade kudzu wreaths in her North Knoxville art studio.
Kudzu, native to Asia, was introduced to the South in the late 1800s as an ornamental plant. It was later thought to be an effective tool against soil erosion, with three million acres of kudzu planted on farms in the late 1940s. Now, kudzu is estimated to spread at a rate of 50,000 hectares per year.
On a grassy hill on University of Tennessee’s campus, Sam Adams, the university’s arborist, pointed to a group of trees across a creek smothered by kudzu. It climbs on sturdy structures such as trees and buildings to get as much sunlight as possible. Trees covered by kudzu cannot photosynthesize, effectively killing them.
“That was not like that just several years ago,” he said, “and they're probably still alive currently, but they won't be for long.”
In season, the vine can grow up to a foot per day. Adams said that small patches of uncontrolled kudzu on campus went from covering 50 feet of land to an acre in less than two years.
“You can see a change from day to day in the midst of the growing season,” Adams said. “It really does grow that fast.”
Patches of kudzu also grow in low-light areas by building up soil nitrogen in its canopy. Studies have shown that bigger patches of kudzu can lead to higher nitric oxide emissions, which increase ozone levels, affecting air quality. When a patch of kudzu dies, chemicals in the vine prevent other plants from growing in that area.
“Our native diversity in the southeastern U.S. has the highest diversity of anywhere in the U.S.,” said Jennifer Franklin, a professor of forest restoration at the University of Tennessee, “I'd like to keep it.”
During a demonstration, Franklin dug out a kudzu vine wrapped around a young hackberry tree on a hill undergoing restoration. At the bottom of the vine was a hardy, ball-shaped root called a tuber. The tuber stores the vine’s energy. Franklin placed the dug-out vine on a branch away from the ground to dry out. If it touches the ground, it can quickly place roots.
Clearing a patch of kudzu can take years. The city of Knoxville’s public service department maintains 46 public areas that have the biggest issue with kudzu. The city spends $20,000 a year on the vine.
“I would definitely say it’s a pretty big issue,” said Knoxville's public service director Chad Weth.
Knoxville Mayor Indya Kincannon recently unveiled a plan to boost the city’s tree canopy and mitigate invasive plants, including kudzu. That plan is expected to be ready by January.
