(Dec. 29, 11:15 a.m.) The Florida fresh citrus industry remains optimistic that citrus canker and citrus greening, two diseases which have decimated the state’s fresh citrus production for the past several years, will one day be eradicated.

It’s betting $20 million — money typically used by the industry for such discretionary expenses as advertising — over the next year based on that outlook.

Just don’t expect it to happen any day soon.

“Researchers have made big leaps and bounds,” said Doug Bournique, executive vice president of the Indian River Citrus League, Vero Beach, Fla. “The research is starting to show some promise. But there’s no silver bullet yet.”

Canker, a bacterial disease that causes blemished fruit, first was detected in Florida in 1995 and was the target of an 11-year, $1.6 billion eradication program. A much more insidious and severe infection is Huanglongbing, also know as citrus greening, first detected in Florida three years ago. Infected trees produce bitter and misshapen fruit.

The resulting spread of disease, in addition to other factors such as hurricane damage, development and growers leaving the business, has eaten away Florida’s citrus acreage so that, last year, the state reported its lowest acreage being used for citrus production — about 577,000 acres — since the state began keeping records in 1966.

“(That’ll be the record) until next year,” said George Hamner Jr., president of Indian River Exchange Packers, Vero Beach. “That total will be even lower next year.”

While only about 4% of Florida’s oranges ship fresh, 41% of its grapefruit and 57% of its tangerines ship fresh.

Disease-proof trees

Most growers, if not all, agree that the answer to the challenges of canker and greening rests with science. Canker and greening will be defeated only when disease-resistant trees supplant current acreage.

But that takes time, said Andrew Meadows, director of communications for Florida Citrus Mutual, Lakeland.

Meadows said scientists at Southern Gardens Citrus Processing Corp., Clewiston, Fla., have completed field trials with specifically engineered tree stock resistant to canker and greening. Such trees are scheduled to be planted in early 2009. Genetically altered red grapefruit trees already have been shown to resist both diseases in lab tests by researchers at Texas A&M University, College Station.
Southern Gardens, an orange juice processor, has been working with university since 2007 to develop disease-resistant citrus trees.

“Disease-resistant trees are the Holy Grail for the long term,” Bournique said.

But Meadows cautioned: “That’s in its infancy stages. That’s a long-term solution. Resistant trees are not going to be planted in the next year or two. We’re looking at four, five, maybe 10 years.”

Pest control

Researchers also are encouraged. Calvin Arnold, laboratory director for the U.S. Department of Agriculture Horticultural Research Laboratory, Fort Pierce, said researchers there have isolated sex pheromones of the leafminer, the insect that carries the canker pathogen. They’ve developed a method of introducing it into trees, disrupting the mating process.

“This will reduce the amount of infection, not eliminate it,” Arnold said.

Arnold said researchers also are working to obtain the DNA sequence to the pathogen of psyllids, the insects that carry the greening bacteria, which can be useful in creating disease-resistant plant stock.

“Greening is a very high priority,” Arnold said. “We’re excited about the money coming in for that.”

For the short term, the industry is doing its best to manage the spread and severity of the two diseases.

Texas and California are also working on initiatives to eliminate citrus greening. In October, the Texas Department of Agriculture established a task force to study how to minimize the psyllid population, protect the citrus nursery industry and develop a citrus greening management plan.

In November, the USDA pledged $5.8 million to the California Department of Food and Agriculture to help eradicate the pest.

“The focus now,” Meadows said, “is to provide a bridge (to the day of resistant plants) that gets us through that lag time.”

For the most part, that involves ever more vigilant inspection of Florida’s citrus groves.

“As growers, from a production standpoint, we’re vigorously inspecting,” Hamner said. “Three to four times a year, we’re walking groves and inspecting trees. If we find a tree infected with greening, the first thing we do is kill it. With canker, we’ve found that we might be able to trim the (infected portion off the tree).”

Spraying programs

Another area currently under research is the development of spraying methods to combat the psyllids. Bournique pointed to research on spraying for psyllids and mosquitoes at the same time.

“That hasn’t been tested yet,” Bournique said.

For now, however, the research and ongoing control efforts are enough to give citrus growers hope that a solution to the scourges of canker and greening isn’t too far off in the distance.

“Our industry’s contracting, and it’s going to keep contracting,” Hamner said. “But it’s not like we’re going to run out of fruit for a long time. And I believe that the technology will be developed to meet these challenges.

“We can last easily (for 10 years). But, in the meantime, we’re going to see less supply and higher prices.”