Root Nutrition Key in HLB-Infected Trees

Ernie NeffCitrus Greening, Nutrition

HLB root nutrition
HLB root nutrition

Jude Grosser

University of Florida researcher Jude Grosser focused on root nutrition during the Citrus Nutrition Day at the Citrus Research and Education Center on October 11. In this report, he says citrus roots impacted by HLB are missing the nutrients they need and discusses possible solutions, including what he calls “hybrid nutrition programs.”

“We’ve gotten kind of too focused on what’s going on in the leaves and kind of forgot about the roots,” Grosser says. “So I just started looking at the roots and found that deficiencies of these important nutrients were greater in the roots than they are in the leaves. The roots are responsible for mining and delivering the nutrients to the top of the tree. So when that ability is compromised, it’s no wonder that the tree can’t stay healthy and produce fruit.”

“I broadly defined hybrid nutrition programs as something where you’re using multiple sources of nutrients in the delivery system,” Grosser says. He says such a program is needed because a grower making four applications of dry fertilizer a year can’t keep nutrients in the root system year-round. He offers examples of programs that can keep fertilizer in the root zone, including controlled release fertilizer and liquid fertilizer. “It’s combining different delivery methods to make sure that you have a constant supply of all the important nutrients over the entire year.”

Grosser urges growers to have patience because it can take a year or longer to institute a good hybrid nutrition program and see the results. “You have to regrow a whole new feeder root system and have the tree in a balanced state where you can maintain that,” he says. “That whole process takes time.”

The researcher also says he doesn’t think the high cost of controlling HLB-spreading psyllids is sustainable. “We can’t continue to spend $2,000 per acre per year in the long haul,” he says. “So we have to find more economically viable ways to keep our trees healthy and productive. I think this (hybrid nutrition) is going to play a big part in that.”

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Ernie Neff

Ernie Neff

Senior Correspondent at Large