South Florida Sun-Sentinel.com

Invasion of fig whitefly threatens South Florida ficus plants

Popular landscaping plant is invader's favorite meal

By Diane C. Lade

South Florida Sun-Sentinel

July 24, 2008

Voracious invaders are sweeping across South Florida, pushing their way northward and devouring the landscape. It might sound like the script for a summer thriller. But the villains actually are tiny fig whiteflies. And they are laying waste to ubiquitous ficus trees and hedges from Miami-Dade to Palm Beach County.

The bug, Singhiella simplex, was not seen in North America until last year, when it surfaced in Miami.

The whitefly's formidable appetite is focused on one of South Florida's most widely used landscaping plants — the weeping fig, or Ficus benjamina — which gives the pests potential to do millions of dollars in damage.

For years, ficus was one of the area's most common landscape plants because of its ability to quickly form a dense screen. Ficus hedges and trees, prized for their shade-producing canopies, line South Florida's roadways, circle homes as privacy hedges and grace local parks.

Plant experts are urging municipal governments, parks systems and homeowners to watch for whitefly signs, such as eggs on leaf undersides, yellowing leaves or leaf drop. They suggest protecting ficus with insecticides poured into the soil, expensive treatments that may be best applied by professionals. The insects live only several weeks but are fast-moving, and infestations spread quickly.

"We're in the middle of an epidemic," said Michael Orfanedes, a commercial horticulture agent with the Broward County Division of Agriculture and Extension Education in Fort Lauderdale. "People need to realize what is at stake if they don't treat their hedges, and what it will cost them if they do treat."

The pest also has been found on several other types of ficus besides the weeping fig, including Ficus bengalensis , also known as the Banyan tree. Ficus usually survive defoliation, but it stresses the plant, making it susceptible to other diseases.

New invasive insect species "are a pretty big deal," said Catharine Mannion, an associate professor with the University of Florida, as horticulturists must figure out what plants they prefer and how to kill the newcomers. Based at the Tropical Research and Education Center in Homestead, Mannion has been gathering information on the fig whitefly and working on treatments since last summer.

Mannion couldn't put a dollar value on the devastation fig whitefly has caused so far. But the mid-1980s infestation of silver leaf whitefly, probably an insect relative of the new South Florida invader, attacked the nation's cotton crop and did $500 million damage in one year. Miami-Dade County's government has allocated $220,000 to fight the pest and already has treated 10,600 trees and 21,120 feet of shrubs.

Pembroke Pines is working up a budget request now. Shawn Denton, director of public services, said the city already has started both the soil drench treatments as well as aerial spraying.

Denton also is warning neighboring cities, "so we don't scare the bugs off our land and onto theirs," he said. Many homeowners and public entities have been slow to identify infestations. Whitefly eggs and nymphs are tiny and hard to see, and their damage mimics what happens in drought.

Extension agents in Broward and Palm Beach counties are doing whitefly training programs for landscape and horticulture professionals.

Planting ficus has been discouraged in recent years because of the plant's invasive root system and the tendency for ficus trees to blow over in hurricanes. So nurseries now produce less of it. Jamie Hayes, general manager of Runway Growers in Fort Lauderdale, said whitefly hasn't affected his wholesale nursery business so far and anticipates it will be more of an issue for maintaining landscapes.

But Lance S. Osborne, professor of entomology for the University of Florida, said European businesses are wary of buying American-grown plants that may have been exposed to whitefly. The state is doing spot inspections of nurseries and those found with fig whitefly are quarantined until the bug is under control.

And where exactly did this whitefly come from and how did it get here? It remains a mystery, Mannion said, although the insect does exist in China, Burma and India.

But no one is surprised that the invaders would make Florida a home base. With its warm climate, the state ranks second in the nation behind Hawaii in the number of new invasive species, with a new pest becoming established here every month, Osborne said.

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