Crazy over Kudzu

Graduate student Sue Carstensen

is all wrapped up in the pesky vine

By Allison O. Adams

From the Emory Magazine kitchens
Click here for a kudzu quiche recipe

On any summer day, motorists in rural Georgia or South Carolina might catch a glimpse of Sue Carstensen tromping through a massive patch of kudzu, a machete in one hand, an insect-collecting net in the other. Often, the sea of green vines engulfs Carstensen's five-foot-three-inch frame, comically revealing only the bobbing top of her sun hat to the roadside observer.

"Out in the country, where I go," says Carstensen, an assistant professor of biology at Columbia College in Columbia, South Carolina, "people are wonderful, but they really think I'm crazy. I'll see the same cars go by lots of times. Eventually somebody will stop and get out and holler into the field, 'Are you okay?' And I'll answer, 'Yes, I'm fine.' Then they'll shout, 'Are you sure you're okay?' It will take me ten minutes to wade through the kudzu to them and explain what I'm doing."

As Carstensen, who hopes to complete her doctoral degree in biology at Emory this year, tells gawkers, she is an ecologist devoted to the study of kudzu, the aggressive, twisted, broad-leafed vine that covers some seven million acres of the South. Imported from Japan as an ornamental vine in 1876, kudzu was touted by the U.S. Department of Agriculture (USDA) as a way to control erosion and replenish depleted fields in the Depression-era South. Several decades later, the USDA listed it as a "noxious weed" because of its uncontrollable growth. Today, kudzu dominates the southern landscape, growing up to a foot a day and turning trees and telephone lines into the monstrous figures Carstensen calls "kudzillas."

Such scenes captivated Carstensen, an Iowa native, during long childhood road trips south to Florida for family vacations. "I saw the most wonderful shapes," she says, "and my imagination just went crazy."

When she returned to the region as a graduate student in the 1980s, Carstensen's captivation turned into scientific curiosity. "At first, I was trying to find out why this plant is so successful here," she says. "When I started asking around and looking at the little bit of literature that's out there, the universal theme was that nothing eats kudzu, that it escaped from its enemies that kept it controlled and contained in Japan. And from an ecological point of view, I found that hard to believe. Every report says it's very palatable and nutritious, and it's been here one hundred and twenty years. How can it go through three hundred insect generations without anything switching to it?"

Carstensen's research may disprove some common assumptions about how best to control the plant. In the thousands of hours she has spent neck-deep in kudzu, she has captured insects in her net and collected five square meters of vines at a time to analyze their growth. She has fed kudzu to various insects to see how they would respond. And she has gathered data from Japanese kudzu fields.

Although she is still analyzing data and has not drawn any conclusions, Carstensen did find nearly seventy kudzu-chomping insect species in the United States, including grasshoppers, leafhoppers, squash bugs, and caterpillars. In her comparisons with the Japanese fields, she learned that, contrary to popular belief, kudzu growth in the United States is not dramatically different than in Japan. "And the insects don't do a lot of damage in either place, which is unusual," she says. "Usually they eat somewhere between five and fifteen percent [of any kind of edible plant]. But with kudzu, it's between three and seven percent."

The plant's best defense against its predators, Carstensen hypothesizes, may be its rapid growth. In some cases, insect populations grow so quickly that they use up their food resource. "But for kudzu, every leaf is cheap," she says.

Carstensen's insights provide a step toward discovering efficient and ecologically sound methods of controlling the plant. But she is also a proponent of finding ways to use the pesky vine. In Japan, where kudzu is commercially cultivated, starch from the root is transformed into tempura batter, tofu, noodles, and gelatinous confectionery delicacies. Paper and textiles are also made from the vines. Carstensen has woven the vines into baskets, and she favors several recipes for the more tender leaves.

"I'm looking at how we can control it so that we can get its benefits without being at its will," she says.

Carstensen maintains a fondness for kudzu. "They really evoke a southern sense to me, these kudzillas and blankets of lush, rolling fields. Much like you have to admire southern tenacity as a culture, you have to have some admiration for kudzu, because no matter how hard people try to control it, it still does its own thing."

Kudzilla photography by Michael Hooten

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