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UF/IFAS Researchers Wary Of Aquatic Soda Apple

GAINESVILLE—Florida’s wetlands already have enough pressure from pollution and other byproducts of development. But now comes an exotic weed that could threaten the fragile biological diversity of many of these marshy refuges.

University of Florida researchers are keeping a wary eye on a troubling new visitor to wetlands in Southwest Florida, fearing the weed could turn out to be the swampy equivalent of the disastrous tropical soda apple. The new weed, aquatic soda apple, is a relative of the tropical soda apple, which has turned into a nightmare for Florida’s cattle industry as it destroys pasture land.

The prickly aquatic soda apple has been located in Highlands, Glades, DeSoto, Charlotte and Lee counties, said Alison M. Fox, a research professor at UF’s Institute of Food and Agricultural Sciences. The weed is believed to have come to Florida from Mexico and was first reported in a marsh south of Punta Gorda in Charlotte County in 1983.

Aquatic soda apple may be recognized by several features including the fact that it always grows in wetlands. The leaves have wavy edges and, with a typical length of six inches, are three to four times longer than they are wide. There are prickles on both sides of the leaves and all the 1/4-inch-wide stems. These prickles allow the stems, which may be six to 15 feet long, to tangle and interlock, much like brambles. The white and yellow flowers develop into clusters of 1/4-inch diameter berries which are initially a solid green in color but ripen to orange and finally a bright red.

As concerned as she is about the aquatic soda apple, Fox is also apprehensive about creating a panic: Research is only beginning on the aquatic soda apple in Florida; There is no evidence as of yet to indicate this aquatic weed will spread as rapidly as its upland relative.

Still, a bit of prevention can go a long way. “This is the early stage of invasion that the tropical soda apple researchers wish they could go back to,” said Fox.

Adds Jeff Mullahey, the tropical soda apple’s chief fighter and acting director of the Southwest Florida Research and Education Center: “It’s better to be safe than sorry. One thing we’ve learned from the tropical soda apple is that prevention and early control will save the taxpayers a lot of dollars.”

The straggly plants tend to clamber onto other plants, including bushes and trees. The biggest clusters have been discovered along the Peace River and at Fisheating Creek Wildlife Refuge, the latter site has seen an explosion of the weed into a 150-acre area with such dense growth in much of the cypress swamp that the thicket can only be penetrated with the aid of a machete.

The woes surrounding the aquatic soda apple are at least two-fold, explained Fox.

One is rather annoyingly simple: The plant can readily restrict access to waterways for not only animals, but humans. Wading through the plant’s prickles can prove frustrating, if not painful.

But the weed may be more than an inconvenience. Fox fears that aquatic soda apple could choke out other vegetation — including some that is rare or threatened — in the wetland area. At the least, this plant pest could upend the wetland’s sensitive ecosystem enough to disrupt wildlife patterns and destroy the unique characteristics of some of Florida’s wetlands.

Another way to look at it is the way that Mullahey views the tropical soda apple. He calls it a “biological pollutant. . . It’s a threat to agricultural production; it’s a threat to Florida’s biodiversity. This is a nasty, no-good plant.”

Again, Fox stresses that research is only beginning on the aquatic soda apple. For example, she said it will probably be a few more weeks before she can say definitively if cold kills the plant. Right now, she said, that appears likely — but the seeds may still survive.

Thus, cold weather could slow the aquatic soda apple in North Florida, but probably not stop it entirely. “It would be like an annual plant,” she said.

A variety of herbicides appear effective on the weed. But because these weeds are in wetlands, Fox said, the choice and use of such chemicals are necessarily restricted.

Fox said she feels a bit tugged from two directions. She is apprehensive about creating publicity over a plant that may turn out to be only a minor threat to Florida’s wetlands. Yet she also knows that if the aquatic soda apple does turn out to be an environmental disaster, attacking it as soon as possible will not only save tax dollars, but Florida’s precious wetlands.