Citrus greening disease occupies a big part of Bob Rouse’s thoughts these days.

The citrus horticulturist at the University of Florida’s Southwest Florida Research and Education Center at Immokalee, thinks he and his colleagues, as well as the state’s growers, will be wrestling with it for a long time to come.

“We’re going to have to learn to live with it,” he says. “I wouldn’t bank too much on a solution from biotechnology within the next 20 years. If we had a GMO today that would work on it, it would take 10 years-plus to get permission to use it in the field. First, we’d have to test it, then get EPA’s permission to put it in the environment.”

And, whether the public would accept genetically modified citrus is another unanswered question.

But with any biotech solution beyond reach, for the time being, Rouse says, growers have to combat greening with already-available tools. He thinks the best option, in many cases, is an intensive micronutrients program, possibly combined with vigorous pruning.

“As long as the leaf is green and functioning, the tree is fine; where the leaves are functional, the tree will keep going. We discovered that where micronutrients were working, root density could increase on a diseased tree.

“Most growers didn’t know what to do when greening first appeared. They stalled a couple of years and got into a recovery mode.”

In 2008, Rouse began testing trees at the experiment station that were almost 100 percent infested with greening. He was intrigued by the observations by Maury Boyd, a southwest Florida citrus grower, who believed a micronutrient cocktail involving as many as 14 compounds could extend the productive life of greening-ravaged trees.

“Was there something unique about Maury or his location? We wanted to find out. Obviously, something was working. That’s what we learned in the last four years. Our experiments all have controls. Some trees are untreated; other trees get some of the components in this mix, but have one thing or two things left out.