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Science fails to support ban on citrus

The state says politics, not a canker threat, led to a shipping quarantine. A USDA report appears to confirm that notion.

By WILLIAM R. LEVESQUE
Published June 28, 2006

As the U.S. Department of Agriculture announced a quarantine of fresh Florida citrus earlier this month, an agency spokesman said the move was essential to halt the spread of citrus-damaging canker outside the state.

The decision barred the shipment of fresh Florida citrus to other citrus-producing states and territories where canker doesn't exist, a potentially devastating blow to some growers. In Florida, canker is out of control.

"We believe that we have the science on our side," USDA spokesman Jim Rogers said June 6.

But the USDA announced the quarantine despite the findings of its own scientists, who concluded in a report about two months before the announcement that it was highly improbable that canker could be spread by the shipment of infected fruit. The study is awaiting peer review.

The scientists concluded that there is "no authenticated record" that canker can be spread by shipped fruit "despite a long global history of commercial trade in citrus fruit. ... There is no record that either infected fruit ... or asymptomatic fruit are epidemiologically significant with respect to the initiation of new infections."

The conclusion in that report by scientists in the USDA's Animal and Plant Health Inspection Service in Raleigh, N.C., is no surprise to Florida scientists, who themselves found in the 1990s that canker could not be spread by the shipment of infected fruit.

And to Florida Agriculture Commissioner Charles Bronson, the report reaffirms his belief that the USDA simply buckled to political pressure from states that compete with Florida in the fresh fruit marketplace.

Asked to confirm the study's findings that canker is unlikely to be spread by the shipment of infected fruit, USDA scientist Ron Sequeira, who helped write the document, said, "Yes, that's the general gist." He then declined to speak to a reporter without permission from the USDA's legal and public affairs staff.

The USDA did not respond to a request by the St. Petersburg Times to interview those who worked on the report, including Sequeira.

Rogers, the USDA spokesman, said barring the shipment of fresh Florida fruit was still found necessary despite the report's conclusion. The decision had nothing to do with politics, he said.

"It doesn't say that canker can't be spread," he said of the report. "You have to remember that while something says the risk is low, we still have to approach the problem from the standpoint: Is it an acceptable risk? Sometimes an acceptable level of risk turns out to be no risk at all."

He downplayed the resulting damage to Florida's citrus industry, saying Florida could still ship fruit to noncitrus-producing states.

"We do allow the movement of fruit out of Florida, just not to places where the risk is highest," Rogers said. "If the fruit's going to Upstate New York, it's not a risk."

To Tim Schubert, a scientist with the Florida Division of Plant Industry, the risk is virtually nonexistent, something he said many scientists have long known.

"Traditionally, there has been a knee-jerk reaction when canker appears in an area, that being you can't send any fresh fruit out," said Schubert.

"A careful analysis of the risk indicates that is probably an overreaction."

Schubert and other Florida scientists concluded in the late 1990s that canker could not be spread by the shipment of infected fruit, an opinion that Schubert said USDA scientists "signed off" on.

In fact, the report Schubert helped write is listed in the notes of the March USDA study.

"I don't think anybody can point to any empirical evidence that canker has ever been spread by shipping fruit," Schubert said.

Bronson said at the time of the quarantine announcement that he thought the USDA decision was based more on politics than sound science.

On Tuesday, Bronson's spokesman, Terry McElroy, said the department still thought politics were at play, noting the USDA took extensive comment from California growers before imposing the quarantine.

"The final word on this from a scientific standpoint is the USDA's own report," McElroy said. "That's their science. That's their scientists. That's their report."

The USDA has acknowledged taking comment from California growers.

"If the science governs here, of what relevance would having discussions with California growers be?" McElroy said. "Why would you do that?"

A call to California Citrus Mutual, the state's largest growers group, was not immediately returned on Tuesday.

But Rogers said the USDA had contact with growers in several states, including Florida, to get input on a potential quarantine. "Everybody was putting political pressure on the USDA," Rogers said. "This is what we do. We get political pressure from all sides on an issue."

Canker, which damages citrus but is harmless to humans, has infected more than 65,000 acres of Florida citrus, spread mostly by the high winds and rains brought by hurricanes of the past two years. The USDA announced earlier this year that the disease could not be contained, a decision that quickly led to the quarantine.

Once it is imposed, probably by October, the quarantine will prohibit Florida growers from sending fresh fruit to California, Texas, Arizona, Louisiana, Hawaii and Alabama, as well as Guam, Puerto Rico, American Samoa, the Virgin Islands and the Northern Mariana Islands.

For Florida's $9-billion citrus industry, the overall impact of the quarantine, while potentially ruinous to some, is relatively small, since 95 percent of Florida's oranges are used to make juice. Last season, the industry shipped roughly 1.2-million boxes of fresh fruit to other citrus-producing states, a market valued at nearly $15-million.

Florida had proposed an inspection program to the USDA to guarantee that shipped fruit did not originate from infected trees or groves, a compromise rejected by the agency.

The way that the fresh fruit is handled and sorted by shippers goes a long way toward explaining why canker is so difficult to spread through fresh markets.

Schubert noted that most fresh fruit shippers cull fruit marked by imperfections or blemishes, which are a trademark of canker.

"Consumers just don't buy blemished fruit," he said. "Shippers aren't able to net enough of a price for it to make selling it worthwhile."

In addition, shipped fruit is typically treated with a disinfectant that kills the canker bacteria. The fruit is usually washed, sanitized and waxed, procedures that at every step kill the canker bacteria, Schubert said.

But even if the fruit remained untreated, Schubert said, canker would not be likely to survive the shipping process more than one or two days. And even if it did, the bacteria would still have to be spread by coming in close proximity to a noninfected tree and still be numerous enough to be spread, he said.

"You can see the mounting improbability as you go through each scenario," Schubert said. "The risk is so extremely low, we ought to pay attention to other problems rather than choke on this gnat."

The USDA report appears to support Schubert, and notes, "Even if infected fruit were to enter a canker-free area with susceptible hosts, the establishment of citrus canker via this pathway is highly unlikely."

William R. Levesque can be reached at levesque@sptimes.com or 813 226-3436.

[Last modified June 28, 2006, 01:34:53]