"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.