Citrus greening, a tree-killing disease first found in Florida last year, has spread into the state's commercial groves and could be a bigger threat than the canker that growers have battled for a decade, industry officials said Thursday.
Greening is a bacterial disease rapidly spread by an insect, the citrus psyllid. It moved into Florida just as the state's US$9.1 billion citrus industry abandoned efforts to eradicate citrus canker and turned instead to learning to live with that disease.
"We cannot live with citrus greening," a University of Florida citrus researcher, Dr. Jim Graham, told growers gathered in Bonita Springs for the Florida Citrus Mutual industry conference. "We're not doomed, but you can't just sit there with your hands folded."
Greening was discovered in a backyard grapefruit tree in Miami-Dade County in August, the first time the devastating scourge was confirmed in the United States.
The infection is now present in all the urban southeast Florida counties and has spread into central Florida's commercial groves, though so far at low incidence, Graham said.
Neither canker nor greening harms humans. Canker is caused by windborne bacteria that weaken trees and make the fruit drop prematurely. Greening makes the fruit unpalatable and rapidly kills the trees.
Growers in Brazil's Sao Paulo state have struggled against greening since 2004. They told their Florida counterparts that the disease can be controlled, but only through aggressive inspection of groves, swift removal of infected trees, vigorous use of anti-psyllid pesticides, disinfecting of equipment and growing nursery stocks in isolated, screened enclosures.
"Ninety percent of researchers say that greening is the worst disease you could have," said Dr. Juliano Ayres, scientific manager of Brazil's Fundecitrus, a private industry group. "This is a disease where you don't have options. Either you do the control or you lose your grove in seven to 10 years."
Florida growers, who produce three-fourths of US citrus fruit, have already adapted many of those precautions in their battle against canker, but now must train workers to spot the yellow-green splotchy leaves that are the first sign of greening.
They will also have to spend more money on inspectors and pesticides, said Jim Snively, vice president of grove operations for Southern Gardens Citrus, one of the Florida orange groves where greening has been confirmed.
Southern Gardens lost 800,000 trees to the canker eradication effort, which forced growers to remove and burn any citrus tree within 1,900 feet of an infected one.
The company had 2.5 million trees left when that program ended in January, and has since destroyed 2,000 trees that tested positive for greening, Snively said.
He said he is optimistic his company can control the disease because it is already vigorously fighting it. What scares him most, he told colleagues at the Citrus Mutual meeting, is that many growers haven't started looking for it yet.
"You're going to wake up one day like we did and say, 'Oh my God,"' Snively said.Reuters via Planet Ark
