University of Florida researcher Jude Grosser, best known for his work on citrus breeding, has become a champion of micronutrients to improve root health and battle HLB. At a recent Highlands County OJ Break, he discussed the use of micronutrients, including why he got involved.
“I guess just like any farmer, you don’t like watching your plants get sick and die,” Grosser says. “I got the idea of looking at root nutrition from thinking about the Maury Boyd controversy.”
He notes that Boyd has maintained production in his HLB-infected grove for years. “The data supports that whatever he’s doing there is working,” Grosser says. “And people have tried to repeat (Boyd’s program), but they’ve only captured the foliar part of what he does. The other part of what he does on the ground seems to have gotten lost in the translation.”
The researcher says Boyd uses much compost and calcium nitrate on the ground. “So he has a very strong program to help take care of the roots of the tree as well as the foliar program,” Grosser says. “So those combined seemed to me as something that hypothetically could explain why the trees were doing so good … That’s when I went back and did the greenhouse experiments, determining that infected trees indeed have greater deficiencies of micronutrients … which is not being addressed by a foliar program. I also thought about if there is one or two key nutrients that might be exceptionally important in battling the disease. And so that’s why I designed the (micronutrient) overdose experiment and conducted that in the greenhouse. And now we’re doing a little of that in the field.”
Grosser says some growers who have tried a micronutrient program are getting better yields and fruit quality along with reduced fruit drop. “The growers who are having success have learned that the trees do need a steady supply of the micronutrients – a constant supply all year,” Grosser says. “And they’re bringing out different ways to deliver that. They’re also figuring out that with a liquid program, that the nitrate forms of the nutrients are working very well. I guess that helps get the nutrient into the tree; it’s a more accessible form to the root system … We still don’t know the optimal level of any one nutrient … There’s a lot more to learn, but I think we’re on the right track.”
More research on micronutrients and HLB is needed, Grosser says. “It’s been way more neglected than it should have been,” he declares. “This work should have been going on the whole 10 years we’ve been battling this disease.”
More than 50 growers and others attended the OJ Break that Grosser addressed. The event was hosted by Highlands County Extension director and citrus agent Laurie Hurner.
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