Florida’s Invaders: Kudzu

The Kudzu may well be the most famous invasive plant species in the world. It has been celebrated and condemned in poetry and in folk music, and has been notably referred to as “the vine that ate the South”.

kudzu

Kudzu                                                              photo from USFWS

In 1876, as part of its 100th birthday celebration, the US sponsored a Centennial Exposition in Philadelphia. Countries from around the world were invited to participate and set up pavilions to show off their national culture and heritage. In the pavilion set up by Japan, hostesses handed out a lovely little potted vine related to the peas, native to Japan and China, with sweet fragrant flowers and attractive leaves. It was the Kudzu, Pueraria lobata.

Two of the Centennial’s visitors were Lillie and Charles Pleas, who owned the Glen Arden Nursery in Chipley FL. Enchanted with the attractive little plant, they took a few back to Florida with them. The Kudzu vines found the Florida climate to their liking. In their native Asia, cold temperatures killed the vines back to the rootstock each winter, which limited their growth. But in subtropical Florida they were warm all year round, and grew freely. The vine formed an immense taproot, half a foot wide, several feet deep, and weighing as much as 400 pounds, which then sent out as many as three dozen runners from each root crown. Expanding as much as a foot a day during good summer weather (some legends assert that you can hear a stand of Kudzu vines growing) the runners reached out to cover everything around them. When the stem nodes touched the ground they took root, often then breaking off and forming a new plant. The Glen Arden Nursery began selling them by mail order as garden vines. They became particularly popular in many places as quick-growing shade plants for outside porches and garden trellises.

By the 1920’s, the vine had also been discovered by livestock keepers. Goats, sheep, and cattle seemed to like the plant, it was high in protein and nutrients, and it grew stupendously fast. It seemed like a winner, and Kudzu was now planted in pastures all across the southeastern US. The constant grazing helped keep it under control.

Things really started going wrong in the 1930’s. The Civilian Conservation Corps was formed to provide jobs for people during the Great Depression by carrying out conservation work outdoors. One of its many projects was erosion control, and thousands of people were put to work for the Soil Conservation Service planting ground cover on bare hillsides to prevent wind and rain from washing the soil away. The plant of choice in the South was Kudzu. From Florida to Texas, farm hillsides and patches of bare dirt were systematically covered with Kudzu vines. “Kudzu Clubs” were formed to promote and advertise the “miracle vine”, and the Federal Government went so far as to pay farmers $8 for each acre they planted with Kudzu. It was also used to line bare road banks. In all, the Soil Conservation Service planted 3 million acres with 85 million Kudzu cuttings.

But as the Great Depression dragged on, many farmers found themselves unable to make a living, and in desperation they sold (or simply left) their land and moved to the city hoping to find work. For the Kudzu vines, left behind and abandoned in their fields, it was the opportunity of a lifetime. With no natural enemies and now no farmers or grazing animals to keep them in check, they exploded.

Although the US Department of Agriculture continued to promote the use of Kudzu vines as ground cover through the 1940’s, by 1953 they realized they had unleashed a monster. Throughout the South, the fast-growing vines were now covering over a million acres of rural area and had also invaded urban roadsides and parks. Like a green tidal wave, the dense leaves completely overgrew and covered buildings, fences, road signs, trees, telephone poles and electric lines, and anything else that would hold still long enough, shading out every native plant under it and often forming a solid unbroken wall of Kudzu. The USDA removed the plant from its recommended list of ground covers, but the damage had already been done. By 1972 the Kudzu infestation had more than doubled, and the Federal Government outlawed its possession. By 2015, “the vine that ate the South” was still expanding at around 150,000 acres per year. In Florida as in other states, Kudzu is listed as a Category 1 Noxious Weed.

The search now turned to a way to get rid of it. Unfortunately, Kudzu is resistant to most of the common herbicides, and killing the plants completely requires multiple doses over a period of several years. A number of the plant’s natural enemies from China have been investigated for use as possible biological weapons, including sawflies, beetles and weevils, but nearly all of them turned out to also attack commercially important plants like soybeans. Some farmers have turned to a low-tech solution: a herd of goats or cattle can eat the plants faster than they can grow, but it still takes several years to eradicate it completely. The vine can also be laboriously dug up by hand and burned, but that costs around $2,000 per acre–and since even a single length of runner left behind can root itself and start growing again, it often fails. As of now, there seems to be no good way to eradicate Kudzu once it is established. So perhaps the vine will eat the entire South after all.

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