WASHINGTON — It has caused the southeast millions in property and crop damage, but a researcher in Canada and colleagues at the U.S. Department of Agriculture say the invasive kudzu vine could be an important new source of bioethanol.

Their findings come at a time when experts are rethinking whether corn is best suited for ethanol production as a biofuel alternative to gasoline. The rise in ethanol demand has prompted concerns over food supply shortages, which in turn have contributed to considerable spikes in food prices worldwide.

The kudzu vine could ease the problem, said University of Toronto professor Rowan Sage, one of eight authors whose study was published recently in Biomass & Bioenergy.

The plant is a fast-growing, woody vine that can grow up to 60 feet in one season. Its underground roots, around the diameter of an adult forearm, store plenty of starch essential for ethanol production. Kudzu exists mostly in the southeast but is native to China and Japan, where the starchy roots have long been used for cooking and thickening sauces.

In the U.S., especially in the southeast where it grows rampantly, the plant is considered a nuisance.

"You may have heard of it as 'the plant that ate the South,'" said Sage, who teaches botany and ecology. "It takes over fields, covers trees and houses and causes a lot of economic damage."

Sage and his research team gathered samples of kudzu throughout the South, including in Statesboro, Ga. They found the plant stores the most carbohydrates in its roots; these carbohydrates can be converted into ethanol with yeast.

And unlike corn, kudzu doesn't have high planting and maintenance costs.

"The problem with corn is you've got to grow it, you've got to use a lot of fertilizer and pesticides to plant it and harvest it," Sage said. "Corn is not that big of a gain and some people say that without federal subsidies the corn ethanol market would probably fail."

The study found that the amount of energy that can be extracted from kudzu is similar to that of corn. For instance, 900 to 2500 liters of ethanol can be converted per hectare of kudzu, compared to 2000 to 3000 liters per hectare of corn, Sage said.

But can kudzu replace corn entirely?

"Realistically, it will at best supplement the corn crop by a few percent per year, but this could be a significant boost to rural economies in the Southern USA, and could help keep feedstock supplies up when corn stocks are low, as they will be this year," Sage said.

Kudzu are among several crops and plants being experimented around the world as the price of petroleum escalates and governments try to reduce dependence on fossil fuels.

Brazil, the world's biggest exporter of ethanol, depends on sugar cane. Dulce Fernandes, associate director of Network for New Energy Choices, a New York City-based nonprofit environmental organization, said sugar cane grows quickly and is less resource intensive than corn. However, the United States does not have the right climate to grow it at Brazil's rate. In India, researchers are testing a shrub called Jatropha that is native in many parts of the country.

Fernandes could not comment on kudzu but said a sustainable source of ethanol should be able to grow quickly without huge costs. Also, it should require little to no fertilizers or pesticides that could harm the environment.

"The plant can have positive characteristics that might be sustainable, but we need to consider the way it is planted," said Fernandes.

Ken Smith, chief executive officer of a Massachusetts-based renewable energy development company, said the fact that kudzu is not native could be an issue. Native plants have natural predators and can for the most part maintain themselves without interrupting the ecosystem.

"If we're looking at long-term solutions, we need to look at plants that are native," said Smith of Smith Energy Inc.

Sage said kudzu must undergo further study. It is uncertain whether the plant is economically feasible to harvest. No techniques exist and it remains to be seen whether new farm equipment must be created in order to pull the plant's roots out of the ground. Also, while there is plenty of kudzu in the southeast, an increase in demand could be problematic as current regulations do not allow cultivation of the noxious weed.