Scientists, growers refine nutrient blends for HLB-infected trees

04/11/2013 03:10:00 PM
Renee Stern

"Nutritional enhancement is good, but don't neglect root health and therapy," he says.

That includes not only liquid fertilizer applications but also treatments to control beetles and phytophthora, as well as ensuring proper levels of irrigation.

"Any stress that tree is under, greening makes the problem exponentially worse," he says.

The advent of greening underscores a basic truth, Roka says.

"Good horticultural practices will probably be the salvation of getting through this."

Like any other business owners, growers must maintain their assets—and citrus trees are among a grove's most crucial assets, he says. "They don't respond well to jumping in and jumping out" of basic horticultural maintenance.

But when prices drop, growers tend to reduce costs.

Micronutrients whose correlation to tree health and yields aren't clear-cut may seem obvious candidates for cuts, Rouse says.

Roka has calculated cost comparisons of six foliar nutrition programs, including Boyd's original formula. Total costs top out at $433 per acre for the Boyd cocktail and range downward to $190 per acre for a foliar nutrition program from Chemical Dynamics Inc.

Rouse and Roka are trying to determine which parts of the nutritional programs are most effective and whether they return growers' investment.

"It's hard to tease these apart," Roka says. Zinc by itself, for example, may do less than its contribution in concert with other micronutrients. Cumulative effects may be more important than a single year's applications.

"We're still spending a lot more money on foliar programs than we were before greening," Davis says.

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Maury Boyd    
Florida  |  April, 15, 2013 at 05:15 AM

The article is well written. We apply the materials while the new emerging and expanding flush is developing, before maturity is reached and the cuticle forms. Of primary importance is for the materials to absorb into the new growth. Additionally, where we have poor soils, sandy and low CEC , we apply to the soil compost ( SWFla ) and recently have increased our soil application of calcium nitrate over that of ammonium nitrate. Regarding roots we find no P but have Fusarium ( secondary ?) found on blighted trees ( citrus blight a + 100 year old disease & cause is unknown ). This was confirmed for me when last year we reshapped our furrows ( recut every other middle, deeply, to increase water drainage ) and we found we had a heavy root system through out. Soil testing by all has been limited. Maury Boyd

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