Acid may heal Florida's ailing citrus
Chemical found in aspirin might inhibit spread of greening
Jerry W. Jackson | Sentinel Staff Writer
February 11, 2008
FELDA - Aspirin has been hailed as a miracle drug for people. But can a natural form of aspirin slow the spread of citrus greening across Florida's disease-battered citrus belt? One grower from Orange County, whose family has been raising citrus since the 1800s, thinks it can -- and some scientists say he just might be on to something.
Maury Boyd is spraying thousands of his trees with nutrients and minerals and, yes, salicylic acid, the chemical in willow bark that led to the development of aspirin more than a century ago. It may not be a proven cure for greening, but "this works," said one professor from theUniversity of Florida who recently inspected Boyd's groves near the Everglades.
The sturdy Valencia orange trees are loaded with fruit and seem to be fighting off the worst effects of the disease. By all accounts, the trees should be in their death throes.
Citrus greening has been spreading throughout Florida groves for at least the past three years -- possibly for much longer than that, scientists theorize. Pathologists confirmed its presence in Boyd's grove with lab tests in 2006, but experts say the disease appears to have been there for three to seven years -- long enough to doom the trees and his crop.
Rather than follow the standard scientific advice -- to uproot and destroy the trees in groves with high rates of infection -- Boyd decided to fight back.
"For two years, we've been proactive," he said, hitting the trees with nutritional sprays and a full-blown attack on the tiny citrus psyllid, a flying insect that spreads the organism. At first, Boyd sprayed the trees weekly for the insects "and knocked them back." Then he loaded up on "nutritional" sprays for the trees, particularly nitrogen, phosphorus and potassium. Those are key ingredients in lawn fertilizer and MiracleGro, the popular product that makes flowers bloom and vegetables grow, sometimes to record sizes.
But Boyd said the salicylic acid he adds to the sprays could be a key to holding the disease in check. Some scientists suspect that the naturally occurring plant hormone, used by organic farmers to boost disease resistance, just might be playing a role.
The Boyd and McKinnon families from Orange County began growing fruit on the fringes of the Everglades after killer freezes in the 1980s destroyed millions of trees in Central Florida.
Their harvests, on land just north of Immokalee, were making good progress until a few years ago. ThenHurricane Charley hit. Then Wilma the next year. The following winter, a freak cold snap sent the mercury plunging to 23 degrees. All those blows took a toll, and fruit yields dropped.
"But we realized something else was going on here," Boyd said. Tim Willis, his field-production manager, finally spotted the tiny insect that spreads greening, and eventually the feared disease itself was confirmed by government lab tests. Greening is harmless to humans but in some ways worse than citrus canker, another tree disease common in Florida. It can turn orange juice bitter, deform the fruit and kill trees.
Scientists suspect the organism entered Florida by accident, on plants imported from Asia, and spread at nearly undetectable levels for years until it began to explode in 2005 and 2006. It's now entrenched in citrus groves statewide. Eradication has been declared impossible.
Road trip to inspect success
Ryan Atwood, a citrus extension agent for Lake and Orange counties, organized a recent field trip to Boyd's grove near the tiny community of Felda. A dozen or so growers and researchers made the more than three-hour drive from the Orlando area. Others came from nearby LaBelle, Immokalee and Wimauma. Many more from around the world have made the trip in recent months.
Gary Vallad, an assistant professor of plant pathology at the University of Florida's Gulf Coast Research and Education Center, is a vegetable expert, but as he walked through Boyd's grove, he saw similarities between the citrus and vegetables such as cucumbers: They both respond to chemicals that turn on defense mechanisms. He has written about "systemic acquired resistance," or SAR, and "induced systemic resistance," or ISR, and is wondering whether Boyd has stumbled on to a formula, or mix, that induces such resistance.
"This has been known for over 100 years," Vallad said of the fact that plants mount a more vigorous defense against pathogens when they are "inoculated" or "challenged" by certain stimuli. The plants develop a resistance or tolerance against future infection, similar to the way animals can be vaccinated against diseases.
Of course, the success Boyd has seen so far might be short-term or may even be caused by other variables, Vallad and other scientists said.
Boyd has scoured databases and obscure scientific reports for more than a year and found hints here and there that keep him going. He obtained a copy of a letter from Jin Hailing, a plant pathologist with the University ofCalifornia-Riverside, written in September, summarizing some of her work on activating plants' immune responses.
She concluded that salicylic acid should be applied to trees infected with greening, known by its Asian name of Huanglongbing, or HLB, "in a well designed scientific study."
Boyd said he and other growers are not waiting for any such official study, frustrated by the slowness of scientific research and cumbersome government regulations.
Guava plants show promise
Robert Ebel, an associate professor of citrus physiology with UF's Southwest Florida Research and Education Center, said controlled studies do take time, and it's understandable that growers are frustrated by the slow pace. One novel concept being explored by scientists, for example, is that guava plants may give off some compound that inhibits the spread of greening. But the work will take years.
Meanwhile, Ebel, Vallad and other researchers fear that false hopes might be raised and worthless concoctions peddled to Florida growers before all the facts are known. The "snake-oil" syndrome is well known in agriculture. Boyd said he has no plans to sell or market anything and has freely shared his ideas and strategy with others.
But just as people battling life-threatening illnesses might turn to megavitamins, folk remedies and healthier diets when hope fades, Boyd said, he is giving his trees "a healthy Mediterranean diet" and naturally occurring aspirin. And hoping they are there in the morning.
"We're trying to buy time," he said. "I don't want to see our industry go down."
Jerry W. Jackson can be reached at
jwjackson@orlandosentinel.com or 407-420-5721.
Source:
http://www.orlandosentinel.com/news/local/state/orl-citrus1108feb11,0,3784001.story 
