COASTWATCH Spring 2006 Issue | Story by KATHLEEN ANGIONE
A coastal menace is creeping onto shorelines along the Carolinas.
Like all crafty invaders, this plant travels well, conquers quickly and has a good disguise. It's seeds and broken stems float on ocean currents to root and colonize new areas. It grows rapidly, choking out native plants. And its beguiling purple flowers will turn heads this summer — some out of admiration for its unique blooms, others out of loathing for its tenacious assault on North and South Carolina dunes.
Nicknamed "Kudzu of the Coast," beach vitex (Vitex rotundifolia) has spread so far and so fast in the Carolinas that experts are pushing to have it listed as a Federal Noxious Weed.
A deciduous, sprawling shrub native to the western Pacific, beach vitex easily outpaces slower growing natives such as sea oats or the endangered seabeach amaranth, says Dale Suiter, wildlife biologist with the U.S. Fish and Wildlife Service office in Raleigh. "And it may out-compete other rare plants that are not yet listed as threatened or endangered," he adds.
Many sea turtle experts and volunteers also worry about the mat of tangled vines beach vitex forms along the soil. The plant can reach one to two feet in height and 12 feet in diameter, possibly putting sea turtle hatchlings at risk as they emerge from buried nests.
Although there are no research studies to document that problem, Betsy Brabson, a South Carolina resident and sea turtle volunteer, has witnessed the threat first hand.
In 2003, Brabson was called to an unmarked nest in Isle of Palms, S.C., to help some wayward hatchlings confused by condominium lights. Brabson arrived to find a heartbreaking scene: the baby turtles had become tangled in the beach vitex mats.
"They got all caught up and died because of dehydration," she says.
Saturating the South
Scientists introduced beach vitex to the southeastern United States from the beaches of Korea in the mid-1980s, believing the plant could help stabilize dunes.
There is still some debate as to how effectively the plant stabilizes and accomplishes that goal.
"We know it has some bad habits," says Chuck Gresham, a coastal ecology and forest science researcher from Clemson University. "But we don't know if it is doing the job it was brought here to do."
Gresham began trials on Pawley's Island, S.C., last fall to measure the recession of vitex-infested dunes versus those covered with native sea oats.
Based on his conversations with island residents, Gresham speculates most people planted beach vitex there in the early 1990s, when the U.S. Army Corps of Engineers rebuilt dunes destroyed by Hurricane Hugo in 1989. Sea oats were in short supply, he says, so many opted for beach vitex instead.
As word traveled about its high salt and drought tolerances, so did the plant.
To date, no one knows how far beach vitex has spread in the Southeast, says David Nash, the North Carolina coordinator for the Carolinas Beach Vitex Task Force. The task force includes representatives from federal, state and non-profit agencies focused on determining and controlling the spread of beach vitex in the Carolinas. Brabson is the coordinator for South Carolina.
The plant has shown up as far north as Ocracoke Island, N.C., and as far south as Florida and Alabama, according to the task force.
In North Carolina, heavy concentrations of the plant are found on Bogue Banks, including Atlantic Beach, Pine Knoll Shores and Emerald Isle. It also is found from Figure Eight Island to Wrightsville Beach, and on Bald Head and Oak islands.
In South Carolina, most beaches in Georgetown County are saturated with beach vitex, especially Pawley's Island and Litchfield Beach. The plant also is well established in certain areas of Charleston County, including Isle of Palms and Folly Beach.
Most nurseries in the Carolinas have stopped selling beach vitex, and many municipalities are trying to contain or eradicate it.
"Beaches are taking a 'no tolerance' policy toward beach vitex," says Brabson.
In January, Georgetown County, S.C., passed the first countywide ordinance declaring beach vitex "highly invasive" and "a public nuisance." South Carolina's Folly Beach, Edisto Beach and Pawley's Island also have adopted ordinances regarding beach vitex, as have some North Carolina towns, including Bald Head Island and Caswell Beach.
Big Red Flag
Brabson first saw beach vitex five years ago, while walking a familiar stretch of beach between Georgetown and Pawley's Island as a volunteer for the South Carolina United Turtle Enthusiasts (SCUTE).
Her reaction was typical.
"I thought it was pretty," Brabson says, describing how the plant's round, grayish-green leaves and bright purple flowers contrasted with the surrounding vegetation
— mostly tall, wispy sea oats.
She noted a pink beach house nearby, and kept an eye on the unusual plant for the rest of nesting season.
"It grew and grew until it covered the dunes, and I noticed there were no sea oats growing anymore," she recalls.
"The big red flag went up in 2003 when we did the Beach Sweep," she says, referring to the annual one-day litter cleanup of South Carolina's beaches and waterways, sponsored by South Carolina Sea Grant.
That day, Brabson spotted thousands of beach vitex seedlings near the pink house.
One of the most troubling characteristics of beach vitex is its prolific seed production
— it can generate as many as 3,300 viable seeds per square meter, says Gresham.
"On a windy day, you can watch them [the seeds] blow by you on the beach," says Nash, who is also a coastal management specialist for NC Cooperative Extension.
After the Big Sweep, Brabson called Randy Westbrooks of the U.S. Geological Survey. Westbrook organized a symposium for personnel from state and federal agencies, private citizens and representatives from nonprofit organizations to address beach vitex.
The event resulted in the formation of the South Carolina Beach Vitex Task Force, made possible by a five-year grant from the National Fish and Wildlife Service. The group was renamed the Carolinas Beach Vitex Task Force in 2005 when North Carolina officials joined the effort.
The task force encourages citizen involvement, says Brabson. The group often enlists the help of volunteer organizations that routinely walk beaches documenting sea turtle or shorebird nests.
If someone sees beach vitex, Brabson recommends recording nearby streets or landmarks and visiting www.beachvitex.org to submit a report. A task force member will visit the reported area, confirm the identification and help determine appropriate eradication measures.
"We ask people not to pull anything up," Brabson says. "Beach vitex needs to be positively identified first because we have so many native plants on the beach that it could be confused with."
Last summer, the task force received an overwhelming number of beach vitex sightings, she adds. They expect a similar influx this year, as the task force will distribute a pocket-sized, waterproof beach vitex identification card.
"The identification cards will be in the hands of an informed group of beach combers and turtle watchers who can help track the spread of beach vitex," says Barbara Doll, a North Carolina Sea Grant extension specialist. Doll, who works on invasive species projects, helped the task force develop the card.
'Time and time again, the general public has proved to be the most effective early warning network for the spread of invasive species," she says.
Nationwide, citizens have used similar identification cards to help document other nuisance species, such as zebra mussels, purple loosestrife and spiny water fleas.
"Citizen involvement will be a key component in documenting, and hopefully controlling, further beach vitex invasion," Doll says.
As citizens and task force members locate and document beach vitex, researchers are looking at ways to eradicate the plant once it's found. Simply tearing beach vitex from the ground won't do, says Nash. The root ball may still be intact, or stems may break off, allowing the plant to recolonize a cleared area.
Herbicides are a potential option, says Gresham, who is experimenting with different herbicides and application methods on four sites in Georgetown County. Three sites are on Pawley's Island, and the fourth is on Litchfield Beach. Each site contains three test plots ?¢‚Ç¨‚Äù one for each eradication method.
The first method involves cutting beach vitex down to a stump and painting the raw edge with glyphosate, the active ingredient in many common weed killers.
A week after implementing this method, Gresham returned to the plots and planted sea oats. Later this year, he will assess how well the sea oats have established themselves, and how much, if any, beach vitex has grown back.
For the second method, called the "hack and squirt" method in forestry, the plant stem is wounded with a sharp object, and an herbicide with the active ingredient imazapyr is applied to the wounds.
The third method, also borrowed from forestry, involves applying basal paint, an herbicide mixed with light oil, to a 12- to 18-inch section of the vine. The mixture penetrates the bark and seeps into the plant's tissue, Gresham explains.
If the second and third eradication treatments prove successful, Gresham will plant all remaining plots with sea oats. But he won't be able to assess the effectiveness of each method until later this summer.
What will be his criterion for success?
"At least 70 percent of beach vitex is dead in the areas where these methods were used," he says.
Eradicating beach vitex is critical, says Nash. But given the plant's prolific nature, research on herbicides designed to kill seeds also may be needed.
And for an invader with such diverse methods of colonization, multiple eradication efforts seem fitting.
"We're finding that you can't get rid of it with one swipe," Brabson says. "It's a vicious contender."
For more information about beach vitex, or to report a possible sighting, log onto www.beachvitex.org.
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