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- Bob Rouse, citrus horticulturist at the University of Florida’s Southwest Florida Research and Education Center at Immokalee, thinks he and his colleagues, as well as growers, will be wrestling with citrus greening disease for a long time to come.
Want to balance top, roots
“We want to balance the top and the roots so they can grow together and support each other,” he says.
“The top supplies the roots and the roots support the top. The reason the roots are dying is because the top end can’t support them. What we did was buckhorning — extreme pruning that removed most of the top to make it regrow.”
Pruning like that is what growers do after severe freezes to encourage regrowth. The difference, Rouse says, is that the root system is not damaged because of the freeze.
“If we can rebalance the tree and grow back the root and top together, we can use the nutrient cocktail mix we’ve seen is effective and really feed and bring the nutrients to the top of the tree.
“But we’re also feeding it with foliar sprays, with liquid fertilizer to encourage new regrowth. We’re using both macro- and micronutrients — key micronutrients, along with N and K, very little P, and some phosphite added. It has some fungicidal activity and is a very good carrier of nutrients into leaves.”
How long will the rehabilitated trees last?
“Right now, no one can say,” Rouse says. “Psyllids are attracted to young growth. The more we learn about greening, the more we learn we need to investigate. This project just keeps getting bigger and bigger.”