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City wages war against exotic air potato species

By Staff | Nov 17, 2010

Air potato spreads by producing aerial tubers, also called bulbils. The bulbils eventually drop from the vines and sprout new vines in the spring.

A battle against invasive exotic plants that threaten Sanibel’s natural areas has been fought since the early 1980s.

But now, it’s time to wage a full-scale assault against the air potato.

According to Holly Downing, Environmental Specialist for the City of Sanibel, air potato can grow extremely quickly (roughly 8 inches per day) and can rapidly climb to the tops of tree canopies, forming a thick mat that shades native vegetation.

“Back in the early 1900s, Henry Nehrling, a Florida nursery specialist, advocated using the air potato and Brazilian pepper as landscaping plants,” said Downing. “But by the 1940s, he reported that those were some of the most aggressive species and were very damaging to native plants.”

A member of the yam family, air potato is native to Asia and sub-Saharan Africa. Downing explained that some experts speculate that it was brought into the Americas with slave ships from Africa. It is a vigorously twining herbaceous vine that sprouts from underground or aerial tubers. It is easy to recognize by its large, green, heart-shaped leaves. The tuber — also called a bulbil — may be dark coffee colored and warty or light tan and smooth.

Air potato can grow extremely quickly and can rapidly climb to the tops of tree canopies forming a thick mat that shades native vegetation.

While it can be found from the east to the west end of Sanibel, the mid-island commercial and residential areas — between Dixie Beach Road and Tarpon Bay Road — are currently experiencing the worst infestations.

An invasive exotic plant is an exotic — or non-native — plant that not only has naturalized but is aggressively expanding on its own, displacing native plants and wildlife and disrupting natural ecological processes.

In 1996, the city enacted legislation regulating eight invasive exotic plant species that were determined to be the “worst of the worst” invaders on Sanibel: Brazilian pepper, air potato, melaleuca, earleaf acacia, exotic inkberry, java plum, lead tree and Mother-in-Law’s Tongue.

Those eight species may not be intentionally planted, transplanted or otherwise introduced in any way on Sanibel and are required to be permanently removed as a condition of all City Development Permits.

And although the fight is far from over, the city and its conservation partners — the Sanibel-Captiva Conservation Foundation and the United States Fish & Wildlife Service — have won several battles.

Air potato is easy to recognize by its large, green, heart-shaped leaves.

Introduced as an ornamental and for its ability to dry up swampy environments, the last known melaleuca tree on Sanibel was cut down in September 1989. The city also continues to make progress with the island-wide Brazilian Pepper Eradication Program. As a result of this program, Brazilian pepper has been removed from all of Sanibel’s conservation areas and from most of the islands residential and commercial properties.

This winter, the city is asking residents and visitors to help with a new fight against the invasive exotic vine known as air potato.

Recently, Downing learned about grant funding that was available from the Florida Exotic Pest Plant Council (FEPPC), who was providing funding for communities where exotic species had become problematic.

“We had heard that they funded similar programs like ours in other parts of the state, so we figured that we should give it a try,” she said.

Thanks to the FEPPC grant, the city is planning to stage its first annual “Air Potato Exchange Day.” Participants can begin now to collect air potato bulbils and then bring them to the city’s booth at the Sanibel Island Farmer’s Market on Sunday, Jan. 16, 2011.

Downing noted that the vines of the air potato plant may be pulled by hand. The bulbils may be plucked off the vine or picked up off the ground before they can germinate.

“People should start collecting them now, before the leaves fall off,” she added. “When residents collect the bulbils, they should be placed with their household garbage. That way, they will be incinerated.”

Downing also noted that the bulbils are killed when placed in the freezer overnight.

Participants who bring in at least 25 air potato bulbils will receive a free native plant (while supplies last, limit one per household), courtesy of the SCCF Native Plant Nursery. Additional prizes will be awarded for the biggest, smallest and weirdest air potatoes, as well as the most collected bulbils.

For more information, visit the city’s website at www.mysanibel.com or stop by their booth at the Sanibel Island Farmer’s Market, held on Sundays from 8 a.m. to 1 p.m. on the grounds of City Hall, at 800 Dunlop Road.