An Alternative Approach
January 1, 2009 
When grower Maury Boyd learned that likely 25% to 35% of his trees in Felda were positive for greening after initial scouting in 2006, he knew removing that many trees from his grove would essentially put him out of business. So following the recommendation to remove infected trees was a tough choice.
Nutrition At Heart Of Program
Having a lifelong passion for citrus and coming from a family with generations in the business, Boyd was not ready to throw in the towel. He had long been interested with the process of how plants use nutritionals, and more recently how they use their own natural defenses to ward off threats, a process called systemic acquired resistance (SAR). That set him on a path to build on a nutritional approach with applications of salicylic acid in the form of salicylate using potassium and hydrogen peroxide to boost the health of the greening-infected trees. Salicylic acid is the active ingredient in aspirin. Originally, aspirin was taken from the bark of the willow trees. Boyd stresses this approach is not a cure for greening, but hopefully will extend the productive life of infected trees.
“If we removed infected trees, it would have basically put us out of business,” says Boyd. “That is what made us do what we did in terms of applying an aggressive plant nutritional program and salicylate. We are not claiming this is a cure and don’t know what the future holds, but we’ve not had a tree die from greening, and the trees look better now than they did two years ago — even with virtually 100% infection.”
He believes nutritonals, salicylate, and hydrogen peroxide applications are central factors that are boosting his trees’ defenses against greening. In fact, plants naturally produce some of these agents to fight threats. Boyd makes applications during flush when leaves are tender to supplement the trees’ own natural defenses.
“I use the example of why we humans are told to eat fruits and vegetables — because it is good for our health and natural defenses,” he says. “Well, plants need the same thing for their health.”
Short Jump
The transition to Boyd’s current program was not a huge jump, as he had evolved his program over the years to fight other pests and conditions. Years ago, when greasy spot was his main concern, Boyd knew heavy metals like manganese, zinc, and magnesium would help control fungi like greasy spot, so they became part of his dry nutritional applications. Because he has low pH soils, he avoided copper applications, developing a fungus control for rust mites.
Later, in his Immokalee grove, he started seeing phytophthora problems and applied Aliette (fosetyl-aluminum, Bayer CropScience) and later K-Phite (mono-and Di-potassium salts of phosphorous acid, Plant Food Systems) to control the problem. When canker came along, he started applying Oxidate (hydrogen peroxide, BioSafe Systems ) and Serenade (Bacillus subtilis, AgraQuest) for canker control.
Then, along came greening, and Boyd began consulting with Carl Fabry with Plant Food Systems about a salicylate product he was developing called SAver. Fabry pursued this idea on the recommendation of Dr. Hailing Jin, a plant pathologist with the University of California, Riverside.
“Carl got a label for the product as a plant nutritional, and we started applying it as part of a program first on our young block of trees, and then on all groves, including Central Florida, where greening is not present,” says Boyd. “People who have come back to visit the grove a year later say the trees look better today than they did before. We are getting the foliage back on the trees one flush at a time, which is key to producing fruit.”
According to Boyd, yields are holding steady in the face of greening. Last season, his block of Valencia picked 618 boxes per tree-acre and the Hamlins picked 611 boxes. The Hamlin block is on poorer, sandy, rocky ground.
Boyd reckons the costs of his approach is in line with the costs of the UF/IFAS recommended program. The costs for plant nutrition applications are offset by the costs of removing trees and inspecting groves.
Psyllid Control
Boyd says that psyllids are aggressively controlled in the groves, and in fact, he has participated in a number of coordinated area-wide sprays with neighboring growers.
“We had never used pesticides in this grove until two years ago after greening came along,” says Tim Willis, who is Boyd’s grove manager. “We just used oil and had all the beneficial insects and fungus working for us. That is why we avoided copper early on. We had an ecosystem working in the grove, so it was hard for me to come out here with an insecticide.”
Taking Notice
Since Boyd began his program, people have been talking and coming out to see what he is doing. It has not been without some controversy, as his methods are at odds with the research community. But now, the researchers at the Southwest Florida Research and Education Center (SFREC) are studying Boyd’s methods. Other researchers from around the globe also are taking note of his program and some have visited to see it in person.
“We are interested in trying to evaluate his program in replicated trials and look at how the different components are working,” says Phil Stansly, an entomologist at SFREC. “We have three replicated trials running now with nine different treatments. It is still early in our work, but we may have some results to report in the next few months.”
After coming back from being virtually wiped out by the freezes in the 1980s and surviving the hurricanes, there is plenty of fight left in Boyd and he is glad people are taking notice.
“I think people are changing some on greening,” he says. “You are even hearing a few researchers saying that if you are beyond a certain threshold of infected trees, then it doesn’t help to go down the tree removal route.
“We are an open book when it comes to what we are doing, and we are seeing results. We need the scientific community to come in and study this more closely. I am glad to see some movement in that direction.”
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