Kudzu Plant: Source Of Ozone Pollution?

Kudzu, the Southern vine that makes Chia Pets of trees and telephone poles, may have yet another unwelcome characteristic: air pollution.

Researchers believe kudzu is releasing ground-level ozone, contributing to smog, breathing difficulties and global climate change.

"If we're right, then it'll be one more big reason to dislike kudzu," University of Virginia researcher Manuel Lerdau said of his preliminary findings.

The fast-growing plant covers an estimated 11,580 square miles in the United States, primarily in the Southeast. Annually, the vine adds 200 square miles to its domain.

Lerdau and fellow researcher Jonathan Hickman of the State University of New York at Stony Brook said they do not have enough data to state with certainty that kudzu warrants a major effort to curtail its growth. They are hopeful of presenting more definitive findings next year.

Kudzu produces two key ingredients of ozone: Its leaves emit a volatile organic compound called isoprene into the air, and its roots convert atmospheric nitrogen into ammonium, some of which can leak into the soil where it is converted by bacteria into nitric oxide.

In the presence of sunlight, isoprene and nitric oxide mix together to make ozone.

While many plants contribute to ozone pollution, it appears that kudzu works faster and produces larger quantities.

The native of Japan and China was introduced in the United States in 1876 as an ornamental plant at the Philadelphia Centennial Exposition. It was widely touted as a way to control soil erosion, and during the 1930s and 1940s the Civilian Conservation Corps planted vast amounts of the vine.

By 1953, the U.S. Department of Agriculture recognized that kudzu was spreading too rapidly and removed the vine from its list of recommended cover plants.

If the researchers' suspicions prove true, the science could have implications for public policy and the government might want to start attempting to halt the vine's unchecked growth, Lerdau said.