Park winning air potato battle

Lake Seminole Park rangers say a new herbicide has killed about 95 percent of air potato vines in some areas.

By BRIAN MOORE

© St. Petersburg Times,
published June 13, 2001

SEMINOLE -- Officials at Lake Seminole Park are seeing positive results from a second herbicide application aimed at killing tree-strangling air potato vines.

County parks' staff expressed some doubt last fall that the herbicide would be successful on the vines, which wrap themselves counterclockwise around ground level vegetation and crawl to a tree's canopy. There was also a fear that the herbicide might kill native vegetation.

But when Park Supervisor Fred Stager evaluated the park Thursday, he found that 95 percent of the vines had been eliminated in some areas. It has been 20 days since the second application of Garlon 4 herbicide was completed, and it appears only the potato vines have been killed.

"We didn't note any casualties of any non-targeted areas," he said.

About 100 acres of the 258-acre park were canvassed by potato vines, but paying for the treatment won't be the responsibility of Pinellas taxpayers. County parks received a Department of Environmental Protection grant worth $73,408 to pay for the work done by EnviroGlades Inc. of Loxahatchee.

Mark Zeller, a biologist for the DEP in Tallahassee, said the project's price tag probably will not reach that figure. The grant was given on a fee schedule basis, meaning EnviroGlades is being paid based on labor hours, amount of herbicide used and other expenses.

The company will likely return this fall after resprouting occurs. The total cost of the work won't be known until everything is complete. The grant's amount is a maximum figure, but Zeller expects the price to be much lower -- possibly less than $50,000.

An EnviroGlades seven-person crew worked four days cutting vines and applying the herbicide in December, but a frost stopped those efforts. Leaves on the vine absorb the herbicide, which filters down to kill the root. There was nothing to spray after the frost killed the leaves.

In May, the company returned to reapply the chemical to the entire area.

According to the University of Florida Center for Aquatic and Invasive Plants, the air potato is believed to have been introduced to Florida as a food plant about 1905. Today they are still cultivated as food in West Africa where they are important commodities. But uncultivated forms such as those found in Florida are reported to be bitter and can be poisonous.

Ridding an area of air potatoes can be an endless, frustrating task. The vines grow as fast as 8 inches a day, and in late summer and fall they drop as many as 200 potatoes per vine to the ground. Those potatoes, if not collected, sprout a new vine. They can be devastating to palms, oaks and other trees.

EnviroGlades' senior biologist Christopher West tabbed the park's vine growth as moderate to severe. The growth started about 10 years ago, and park staff tried to fight it by cutting the vines for several years. It wasn't until last year that the park was able to secure adequate funding to treat the problem.

It's been a bear of a job for volunteers, who joined the struggle against the vines four years ago.

Since Stager first started keeping records in 1998 on volunteer work to control the vines, better than 34,000 pounds of potatoes and vines have been hauled away. This year, individuals and Girl Scout troops have worked 531 hours in the park and removed 4,741 pounds of potatoes.

Volunteers continue to pick up potatoes at the park and dig up new sprouts. Their job security appears to be at a premium. Even if the herbicide eliminates the existing vines, there's a good chance the problem will resurface.

"There's nothing we can do to prevent it from happening again," Stager said. "The area is really heavily wooded and when these potatoes fall, they bury themselves underneath leaves and pine needles and we can't even see them until they sprout.

"Are we going to have regrowth? I almost guarantee it."

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