Research bolsters foliar nutrients’ role in citrus greening management

10/07/2011 01:32:00 PM
Vicky Boyd

A nutrient cocktail developed by citrus grower Maury Boyd appears to not only rejuvenate citrus trees infected with citrus greening, but also improves their vascular system.

Three years of trials conducted by Bob Rouse, an associate horticulture professor at the Southwest Florida Research and Education Center in Immokalee, have backed up Boyd’s earlier observations that the nutrient blend helped counteract the effects of greening, also known as huanglongbing or HLB.

In addition, preliminary laboratory tests by Ron Brlansky, a plant pathology professor at the Citrus Research and Education Center in Lake Alfred, show the application of the nutrient blend has enabled the plant to produce new phloem—the plant’s nutrientcarrying vascular tissue—in HLB-infected trees compared to untreated ones.

“This raises more questions,” Rouse says of Brlansky’s preliminary findings. “All we know is the first time we ran the dye, and there was a big distinction between the open phloem in the trees that were treated compared to the trees that were not treated. And with Maury’s trees, the samples we pulled from his were open, too.”

Despite the apparent good news, Rouse says he doesn’t view the nutrient cocktail as a silver bullet. Instead, he says, it is a shortterm bridge to keep growers in business until research yields longer-term solutions.

Rouse says the trial results also back up his contention that trees were nutritionally deficient even before citrus greening entered the state.

As fruit prices dropped during the past few decades, growers cut costs, including foliar nutritional programs.

HLB, yet another stressor, simply pushed the trees over the brink.

“We moved from a good nutritional program in the last 20 years to probably a weak foliar nutritional program,” Rouse says. “We were putting everything on the ground because we had been told that a little micronutrient deficiency in the leaves doesn’t affect production. But that doesn’t hold up in the era of greening.”

Early trials

Rouse began his trial in early 2008 at the SWFREC with HLB-ravaged trees that had nearly 100 percent infection. He had nine different treatments, including the full Maury Boyd cocktail, different components of the cocktail individually and an untreated check.

He also had two similar trials in nearby commercial citrus groves, one with about 50 percent to 60 percent infection and the other with about 15 percent to 20 percent infection.


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Manahar Kadariya    
Nepal  |  December, 16, 2011 at 11:43 AM

I also stressed to support this result. here we are doing a trial on 10 different groves for rejuvenation of more than 50 percent declined trees. But we do not have any resources for lab testing of these trees for greening. But most of the plant showed the typical symptoms of greening. Can i go further with farmers to disseminate technology ?

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