Stemming the spread

Since 1996, Florida has destroyed a half-million trees because of citrus canker and plans to remove another 600,000 by year-end. Meanwhile, researchers are struggling to find a way to eradicate the bacteria before it decimates the state's citrus industry.

By KYLE PARKS

© St. Petersburg Times, published June 19, 2000

PALMETTO -- There used to be row after row of citrus trees on Al Repetto's 140 acres just south of the Sunshine Skyway. Now, there's nothing but grass and weeds.

The culprit: citrus canker, a bacteria that refuses to die in Florida.

Canker was first found on the property about nine years ago, and state agriculture officials burned the surrounding trees. Repetto replanted, only to see the disease reappear in 1997, forcing a second round of burning.

Now, he's giving up. He asked the state to remove all his trees. Soon he plans to sell the property to developers.

"The canker thing has gotten out of hand," said Repetto, who has run the Orange Blossom Groves gift-fruit business in Pinellas County since 1946. "But no one wants to admit it."

Florida has been fighting canker for decades, but this is one of the worst outbreaks ever. It has been spotted in six counties, and if it spreads throughout the state, canker could have a devastating effect on Florida's citrus industry.

Widespread canker would cripple the fresh-fruit industry, which accounts for 15 percent of Florida's citrus business. And even though fruit with canker can be sold for processing into juice, diseased trees bear much less fruit, which would hurt the state's production.

By December, state and federal agencies will have spent $250-million over the past five years trying to get canker out of Florida. But this is one stubborn bacteria.

Canker can travel from one grove to another on a fruit picker's clothes or on tree-trimming equipment. Wind and rain can spread it for several miles. And people can unknowingly bring it into Florida when they plant citrus cuttings from such countries as Brazil or Argentina.

The state has removed 500,000 trees in the past four years, and it plans to destroy another 600,000 in the next six months. Several hundred inspectors are constantly searching Florida's groves for new outbreaks.

But there's no way the inspectors can check every leaf on every tree, so the industry needs to update its technology if it is to win this fight once and for all.

The first step: Many growers are now spraying disinfectant daily on pickers and equipment at the entrances to their groves, which can keep canker from spreading.

At the same time, researchers are working on better ways to spot the disease. Could dogs be trained to sniff it out in a grove? Or could an "eye in the sky" imaging system differentiate the sunlight reflected off a tree with the dark blotches of canker?

While the experts ponder such possibilities, Repetto fears for his other major holdings, on 150 acres in south Hillsborough County.

"When you are in this kind of business, you can be wiped out by a freeze, anything," he said. "But canker's tough. I don't know if they'll ever be able to get rid of it."

Citrus canker originated in Asia centuries ago, and the U.S. government has been fighting it since it was discovered in Florida in 1910. A massive eradication campaign finally ended in 1933, and the next major outbreak wasn't until 1986-92.

The latest outbreak started five years ago in Miami-Dade County and has spread to residential areas and groves in six other counties, including Manatee and Hillsborough.

This is a serious threat to Florida's $8.5-billion citrus industry. When a diseased tree, identified by lesions on the citrus and leaves, is found, the state limits how fruit from the surrounding area can be sold.

Growers aren't allowed to replant in a canker-infested grove for two years after the disease is eradicated there. And while fruit from a quarantine area can be sold for processing -- scientists say the bacteria is harmless to humans even though it spoils the appearance of the fruit -- there are restrictions on how fresh fruit can be sold.

The state has been relatively fortunate so far. Grapefruit is most susceptible to canker, but the disease hasn't been spotted in Florida's grapefruit capital, the Indian River area. And the destroyed trees account for only about 1 percent of Florida's 107-million citrus trees.

That percentage may be low, but canker is no small matter for the growers who are affected. Under new state rules, officials pull out trees for 1,900 feet in all directions from an infected tree, not the previous 125 feet. After trees are removed, roots and all, they are ground up or burned.

And while about $22-million has been budgeted by the federal government for emergency aid to farmers affected by canker, the money is tied up in bureaucracy.

Gene Mixon, who runs a small Palmetto packing house with his son Scott, has lost 26 of his 155 acres. Three years ago, they bought a citrus grove after it got a clean bill of health from inspectors. A month after the sale closed, canker was spotted there.

Since then, the Mixons have faced a double whammy.

Besides losing some of their groves, they've had to deal with the quarantine. None of the fresh fruit from their groves can be shipped to citrus-producing states such as Arizona and California, and the rule also excludes other areas of Florida.

The Mixons have scrambled to find new markets, but they've lost as much as 30 percent of their Citrus Ranch fresh fruit business, which accounts for about one-fourth of their $400,000 in annual revenues.

Like Al Repetto, the Mixons wonder if it's worth it.

"You have to have an exit strategy," Scott Mixon said. "What we do is a tradition, but you have to consider that you can get a lot more by building houses on this land than by growing trees on it."

In a nondescript building several miles from the Mixons' groves, 110 state employees plot strategy for killing canker in Manatee and Hillsborough counties.

The command center's wall maps are dotted with push pins marking canker finds. Each weekday morning, Division of Plant Industry inspectors drive off to look over nearby groves for signs of canker.

It isn't easy work, especially in the Florida heat. The inspectors fight boredom as they walk or drive slowly through the groves. When someone reports an occasional sighting of a panther or a rattlesnake, it's news around the office.

Of the 500,000 trees removed so far, about 300,000 have been taken from commercial groves, the rest from residential areas.

For growers, canker means a loss of their livelihood. And for homeowners -- such as in Hillsborough's Sun City Center area, where about 2,100 trees have been destroyed -- it means losing a source of food and shade.

Enforcing the rules has been particularly tough in South Florida, where most of the diseased trees are in people's yards. Though most homeowners have been cooperative, one man defended his grapefruit tree by pointing a gun at a sheriff's deputy. Other officials have been greeted by snarling guard dogs.

Now, workers are accompanied by state and local police.

"In the Hispanic culture, citrus is very important, and it can be difficult to convince people that their trees must go," said Connie Riherd, assistant director of the Division of Plant Industry. "It's a long-standing tradition to have your own trees."

The eradication effort has cost about $80-million in federal and state funds, and officials plan to spend another $171-million in South Florida, the most heavily infested area. As many as 2,000 workers will be involved.

Much of the canker in other parts of the state has been traced to South Florida, so cleaning up that area will help. But getting rid of canker isn't an exact science.

People moving around the state can inadvertently take canker plantings with them. If there is a major tropical storm, as there was last fall in South Florida, the canker may spread far beyond the 1,900-foot tree-removal line. And the disease can lay dormant in a tree for as long as two years before it appears on fruit and leaves.

"The problem is that we haven't really changed how we attack this thing since the 1920s," Riherd said.

At the U.S. Department of Agriculture's horticultural research lab in Fort Pierce, Tim Gottwald is trying to change that.

Gottwald, a plant pathologist, is considered the nation's top expert on canker. He has studied it for more than 15 years, long enough to know how tough it is to fight.

"There is so much more international travel now, and that means the possibilities of introduction of exotic pests is just skyrocketing," he said.

At the Fort Pierce facility, researchers study everything from how pesticides affect strawberries to how plants react to heat and moisture.

Quarantine rules prevent Gottwald from working on canker samples in Fort Pierce, so in the lab he studies bacteria with similar qualities, growing fastest in wet conditions.

Gottwald's corner of the 134,000-square-foot complex features his homemade "spore-release chamber," a device that measures how different conditions affect fungal pathogens. The contraption looks like something out of a high school chemistry lab. It was concocted from an Igloo cooler, bell jars and light bulbs.

"It may look funny, but it's unique in the whole world," said Tim Riley, one of Gottwald's assistants. He was preparing petri dishes for one of the staff's many trips to South Florida, where they use a mobile lab to collect and test canker samples.

Gottwald talks of the strides made in canker research, but he acknowledges there's only so much that can be done with funding of less than $1-million a year.

That's about to change. The U.S. Department of Agriculture is preparing $8-million in grants for canker research, and a group of international experts is meeting with Gottwald this week in Fort Pierce to make recommendations on how to spend it.

"Hopefully, we can start to figure out if canker has a unique signature that can be picked up in different ways," Gottwald said. "Perhaps we could gather an aroma in South Florida from a canker sample and take it back to trained dogs."

He's also excited about the possibility of using aerial imaging systems, which have been used in the Midwest to spot disease and pests in cornfields.

Growers in many parts of Latin America have lost the canker fight, Gottwald said. It's endemic in large parts of Brazil and Argentina, severely limiting their ability to export fresh fruit.

"We hope that will never happen here," he said. "In some ways, fighting it is just common sense, with growers using sanitation methods."

A key part of the effort is the state's growers, who were long reluctant to spend the time and money required to use disinfectants.

To make matters worse, eradication efforts in the 1980s were far from perfect: There were lawsuits after it was discovered that thousands of removed trees didn't have canker.

The Florida Citrus Mutual trade group has helped convince growers to forget the mistakes of the past and focus on today's battle.

"Most growers are now doing the sanitation," said Andy LaVigne, executive vice president of the group. "There has been a change in attitude about it in the past year or so."

But there will be tougher challenges when, or if, this latest outbreak of canker is eradicated.

Will growers be willing to keep up their sanitation practices, a harder sell when there isn't canker nearby? And will there be government money available to keep the state's inspection program going, so canker can be found quickly if it reappears?

"We had better be careful that we don't eradicate the industry as we eradicate the canker," said J.V. D'Albora Jr., a St. Lucie County grower who wrote to Gov. Jeb Bush a few months ago, urging more money for research.

"We need control, not necessarily eradication," he said. "Is there a chemical that would control canker without killing the tree? We don't know yet."

At this point, researchers say chemicals don't seem to be the answer. And with no simple solutions, the state must be prepared for the possibility that canker can't be eradicated forever, Gottwald says.

"Eradication is still a questionable concept," he said. "The jury is out. Part of the answer is putting time and money into it. But there's also more than a little luck involved."

-- Times researcher John Martin contributed to this report.

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