Citrus Researchers Scramble To Get Experimental Trees To Desperate Growers

Nov 29, 2013

Florida citrus growers are desperate for relief from a disease blamed for killing about half their crops in less than a decade. Many in the multi-billion-dollar industry hope to plant experimental trees they’d consider highly risky under normal conditions. But hurdles remain before they’ll have the chance.

Fred Gmitter has just discovered the first signs of greening disease on a 15-year-old tree.

“So, you’re here at a very bad time for me,” he says.

The University of Florida scientist is driving a pickup truck through the Citrus Research Center grove about 45 minutes southwest of Orlando.

“It doesn’t spare anyone,” he says. “Research facilities like ours are just as susceptible to the problem as anyone else out there.”

Gmitter pulls up to another tree with very few leaves and small, inedible fruit littering the ground under it—telltale signs of the disease, he says. It affects the vast majority of trees here and hundreds of thousands more in commercial groves across the state. There’s no known cure. But Gmitter and his partners have been breeding trees that seem to hold out longer before becoming infected.

“Almost all the trees are in decline and dying,” he says. “But you’re walking down a row and suddenly you come to four trees in a row that look good.”

Scientists study these healthy trees Gmitter calls “survivors” to try and unlock their genetic secrets. But survivors are becoming scarcer. Among the unhealthy multitudes, he walks around a lone tree that’s lush and covered in fruit.

“There’s something different about this tree,” he says with a smile.

No infection here, he says. But a closer examination reveals some of its fruit is turning green on the bottom.

“This is also worrisome, the “red nose,” the color inversion,” he says with a sigh. “I don’t think I want to go see any more trees with you today. But this is the nature of the challenge and what’s going on.”

Despite setbacks, Gmitter says his team has developed 16 tree varieties they believe are resistant to greening—at least so far. Usually, they’d study these experimental rootstocks for at least 15 years before selling them. But growers say they don’t have that kind of time.

“Our industry is in steep decline right now. It may be an indication of our desperation, but we need these rootstocks,” says Mike Stewart, horticulture manager for Consolidated Citrus, one of the state’s highest-producing orange growers.

“We hope that they are better—they appear to be better than any other rootstocks that we have available at this stage,” Stewart says.

He says normally his company wouldn’t gamble on buying young, largely untested trees. But after replacing half a million trees in the past couple years, he says experimental is better than dead.

“We would probably be willing to risk putting all of our production on them,” he says.

But before growers can test the stocks commercially, Gmitter says the state must grant a permit exemption that would allow them to be mass produced in Oregon and shipped back to Florida. Just as the Legislature has invested more heavily in greening research, Gmitter says he’s confident the exemption will be granted.

“Many of the politicians recognize that this industry is worth about $10 billion to the state economy, 60 [thousand] to 70,000 jobs. So this is important not just to the farmers who do this, not just to the juice companies, but, you consider the taxes that are paid and what that means to all the citizens of the state of Florida,” he says.

Gmitter and Stewart are on a technical advisory committee that will vote mid-December whether to recommend the exemption. Regardless of the decision, Gmitter says four of the 16 varieties will be ready for commercial trials next summer.