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Florida lab has one objective: Stop citrus greening (w/video)

Fruit infected with citrus greening becomes misshapen and bitter. In a test field in Lake Alfred, the difference between a healthy orange and an infected one is easy 
to see.
Published Feb. 15, 2015

LAKE ALFRED

One of the best hopes to revive Florida's fast-fading citrus industry is a steam generator mounted on an old grove truck.

In a test plot at the University of Florida's Lake Alfred Citrus Research and Education Center last month, the truck lowered a plastic hood over a barren, dying orange tree. Hissing jets filled the enclosure with steam for 30 seconds, long enough to kill the citrus greening bacteria beneath the tree's bark and, probably, restore the tree's health within six months.

"The results have been pretty remarkable," said Reza Ehsani, the leader of the steam treatment project.

In the state's war against highly destructive citrus greening, the work at Lake Alfred is its Manhattan Project. Founded in 1917, the center is touted as the world's largest agricultural research facility devoted to one crop, and today nearly all of its 227 employees are focused on defeating or controlling greening.

It is such a menace that the diseases these scientists once battled now seem like mere nuisances; citrus canker and tristeza are like hemorrhoids, one researcher said, while greening is like liver cancer.

Much of the $90 million raised by growers to fight the disease over the past decade has funneled through the center. And last week Lake Alfred researchers received a major slice of the $30 million in U.S. Department of Agriculture citrus greening grants.

Steam treatment is just part of the center's developing arsenal, which includes antibiotics, new feeding regimens, soil treatments and heavy doses of chemicals. It is also home to research on another, far more controversial, weapon: a genetically modified organism.

"The right GMO," said Bill Dawson, a virologist at the center, "could make people forget all about greening."

• • •

The discovery of citrus greening in Florida 10 years ago sent the Lake Alfred center into "crisis mode," veteran genetics researcher Jude Grosser said.

Greening, a bacteria carried by a tiny insect called the Asian citrus psyllid, kills by attacking the phloem, the tissue that carries nutrients throughout the tree. It now threatens an industry so tied to Florida's identity that the fruit appears on some of its license plates. It imperils the state tradition of backyard citrus and the national habit of orange juice with breakfast.

Consumption has fallen by nearly one-third in the past decade, partly thanks to higher prices caused by greening. Annual orange production in Florida is down from 242 million boxes in 2004 to the 103 million boxes predicted for this year. Acreage planted in citrus dropped by more than a third since 2000, mostly because of greening.

Citrus remains a huge industry in the state, with a total economic impact of nearly $11 billion per year, but greening has cost growers in the juice business $7.8 billion since 2006, according to a recent report by UF economist Alan Hodges.

On a typical day at the center, senior scientists in blue jeans and sneakers gather in the center's offices to talk funding and research. Lab assistants huddle over microscopes. Workers tend to plants in the clusters of grow rooms and greenhouses — some of them behind razor wire because greening was briefly considered a potential terrorist threat. Others employees pick and weigh fruit in the center's 600 acres of test groves.

"We're fighting for the life of an industry," Lake Alfred microbiologist Jim Graham said.

• • •

The center is on the northern edge of the state's citrus belt, and seeing what its scientists are up against requires only a drive through the surrounding, gently sloping hills: abandoned groves, with row after row of dead, bare trees; shriveled and yellowed foliage; trees surrounded by prematurely fallen oranges.

But some growers, judging by their fruit-laden trees, are holding their own against greening. The secret is keeping up with the latest advances and being willing and able to pay for them, said Larry Black, a fifth-generation grower from Fort Meade, about a half-hour south of Lake Alfred.

Black has bulldozed many of the old, sick trees on his 4,000 acres of groves. He replanted at twice the density and expects the trees to live only half as long, about 15 years. He "spoon-feeds" them fertilizer, spraying the leaves with nutrients more than a dozen times a year. To kill psyllids, he applies insecticide "15 times a year as opposed to three or four," he said, one reason the cost of maintaining groves has more than doubled, to about $2,200 per acre.

Black is watching the progress of Ehsani's heat treatment, which received a $3.5 million federal grant last week. The process, one form of which is available for commercial use, can control the symptoms of greening for about two years.

Black has already adopted another Lake Alfred discovery. Graham, the microbiologist, found that raising the acidity of soil counteracts the effects of substances in deep well water that destroy roots in diseased trees.

A combination of such small fixes, Black said, may turn out to be the big fix for greening.

"We're not going anywhere," he said. "We feel we can be successful without a silver-bullet solution, because the reality is there might not be a silver bullet."

But many other growers, big and small, say that without a breakthrough, the industry is in real danger of dying.

Ricke Kress is president of U.S. Sugar's Southern Gardens Citrus in Clewiston, the largest grower in the state. It has spent millions of dollars on research, Kress said, and he is skeptical that fixes such as heat exposure offer a long-term solution.

"We only have 1.8 million trees," he said. "When you have some time over the weekend, you can help us tent them, okay?"

• • •

Grosser is one of the few Lake Alfred researchers hoping to find the big breakthrough in existing citrus trees.

"The prevailing dogma is that (all citrus) gets greening and that there is no hope within the citrus (gene pool)," he said. "We're finding that is not true at all."

His work is not much different than the way citrus breeders have always done things. He looks for trees with desirable traits, in this case tolerance to greening, and crossbreeds them to make these traits stronger.

The work started soon after greening appeared in Florida, when Grosser and other researchers grafted standard orange varieties onto 50 different root stocks in a grove a few miles from Lake Alfred.

On a visit last month, some of the trees were stunted or dead. But one looked untouched by the disease. Its foliage was thick. Its branches drooped under the weight of large oranges, one of which Grosser cut open to offer a sweet and juicy slice.

"That's a beautiful tree," he said.

But a few healthy specimens grown in a test grove are just the beginning. Bringing new citrus to market, even conventionally bred citrus, takes years.

Grosser must first cross the most promising root stocks to make hybrids, which are then put through what he calls "the gauntlet." He starts them in poor soil, grafts the root stock to an infected Valencia top, and then moves the healthiest of these plants to a "hot psyllid house," a grow room where clusters of bacteria-carrying insects cling to the underside of leaves.

It will take years for Grosser to know if the trees that survive the gauntlet are good producers of fruit and can retain their greening tolerance.

Trees must then be screened for a long list of other maladies, a process that has been much accelerated since the advent of greening but is still a major obstacle. Finally, there's the gearing up for commercial production, filling the demand of growers who will want "a million zillion of them tomorrow," Grosser said.

Even then, Grosser said the trees likely will need a high level of care. He does not expect citrus to return to the relatively clean, low-maintenance crop it once was.

"Those days are gone," Grosser said.

Not with the right GMO, said Dawson and other researchers who believe their work can start changing the prevailing use of genetic engineering.

• • •

• ••

Artificially altering an organism's genetic makeup, often by importing genes from another species, has been controversial, partly because GMOs in this country often work in tandem with chemical treatments. The most common examples are Monsanto's Roundup Ready corn and soybeans.

The methods being tested on citrus, on the other hand, could greatly reduce chemical use.

"In my view, if you are opposed to GMOs, you are pro-pesticide," said Dawson, who received federal funding for his work on a genetically engineered virus designed to target psyllids.

No studies have shown that genetic modification on its own is harmful to human health, he said. To ensure safety, he said, the regulatory process for any tree borrowing genes from another source would be exhaustive — requiring several years, tens of millions of dollars and the approval of three federal agencies.

Still, researchers know that orange juice has been pitched for decades as nature's perfect beverage. Tampering with its genes is sure to generate backlash.

So scientists have taken pains to avoid taking greening-resistant genes from unpalatable sources such as jellyfish and have instead stuck to material from plants, the more wholesome the better. Several promising candidates, including trees with genes from spinach and rice, thrive in test plots in other parts of the state.

But another Lake Alfred researcher, Fred Gmitter aims to take a different approach, one that may eliminate the need to import genes as well as some of the obstacles to bringing a genetically altered tree to market.

Gmitter, who previously helped map the citrus genome, is part of a team that received a $3.3 million federal grant to find the gene that makes orange trees susceptible to greening, and learn how to switch it off.

This wouldn't add new genetic material, he said, "just fix something . . . that is not quite working right." If the result is classified as a mutation of an existing tree rather than a GMO, it might avoid the usual GMO approval process. It may even be more acceptable to consumers.

"That's the goal," Gmitter said. "To have a fully greening-resistant tree that's all citrus."

Contact Dan DeWitt at ddewitt@tampabay.com. Follow @ddewitttimes.

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