Signs of Life

Citrus Greening Threatens the Florida Economy and a Cherished Way of Life

Scientists have been searching for ways to combat it. Now genetic research might be bearing fruit.

By Daniel DeWitt December 30, 2016 Published in the January 2017 issue of Sarasota Magazine

Last fall near Fort Meade, 80 miles northeast of Sarasota, Larry Black’s pickup rolled by groves full of orange trees with wizened fruit and mottled, yellowed leaves—trademark symptoms of the scourge of the state’s most iconic crop, the misleadingly named citrus greening disease. Black, who is both a grower and general manager of Fort Meade’s Peace River Packing Co., passed ghostly rows of neatly planted, uniformly sized trees, all of them gray and bare. He looked through his cab window at dead trees that had been bulldozed into piles as big as houses, preparation for the final step of grove abandonment, the prescribed burns that one veteran grower has compared to funeral pyres. The irrigation pipes towering over the bulldozed grove were another sign its time had passed, Black noted. “That was probably state of the art in 1962,” he said.

But not every grove Black drove by was dead and barren. This is the best of the best of the state’s citrus land, with the right soil and climate and gentle hills that protect the crops from freezes. Most of the groves are owned by big, well-financed growers, and the view from the crest of many of these rises was of green and healthy trees. Black could see newly planted, knee-high saplings, each trunk covered by a sleeve of protective plastic. He spotted test plots of citrus varieties that have shown promising levels of greening tolerance, their leaves full-sized and glossy.

And then there was acre after acre of his own densely planted commercial groves, trees just a few years old but already 10 feet high, and on this day in early October loaded with green fruit. Black says that with enough investment and just the right care—with precise doses of water, fertilizer and pesticides—these trees should remain productive for another decade and carry his business through to the other side of this crisis.

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A rotted piece of fruit hangs from a tree infested with greening at the center.

That’s another thing Black, 43, can see—a bright future for Florida citrus—though he’s not sure how many other farmers see it with him. Despite doomsday predictions about the fate of Florida citrus, he expects the industry to break into new global markets. He can look ahead to a time when better growing techniques, hardier varieties and, maybe, a fully resistant, genetically modified tree will make greening just one more in a long succession of setbacks—hurricanes and freezes, lesser citrus diseases such as canker and tristeza—that the industry has moved beyond.

“We are very close to a bottom,” says Black. “At our company, we definitely see a path forward, and we want the industry to have the same momentum—to have these young plantings and this new technology in the field. If it does, the industry is going to first stabilize and then rebound.”

Greening, of course, is far more sustained and destructive than any of these earlier threats. If canker is like hemorrhoids, one researcher likes to say, greening is like liver cancer. Also known as Huanglongbing, and referred to by scientists as HLB, greening is a bacterial disease carried by a gnat-sized insect called an Asian citrus psyllid. It attacks a tree’s ability to take up nutrients from the soil and distribute them to its limbs and fruit. Though some citrus varieties are more vulnerable to the disease than others, none is immune, and it is always fatal.

“There are changes in the pathways that move the sugars. There are changes in the pathways that move all nutrients,” says Fred Gmitter, a University of Florida professor at the school’s Lake Alfred Citrus Research and Education Center. “Anything you can imagine metabolically happening in the plant [can be the result of] changes brought about by this disease.”

The disease was first identified in China nearly a century ago, and has since spread throughout Asia. Scientists with the Florida Department of Agriculture and Consumer Services, meeting to scout for signs of the disease in South Florida in August of 2005, discovered the state’s Patient Zero before they made it to the first grove. Walking to a French restaurant on their first day in Miami, they noticed a sickly looking specimen in someone’s yard and collected what would prove to be greening-carrying psyllids.

Since then, the disease’s spread has been as obvious on spreadsheets as it is in groves. Greening, along with development pressure, has cut the amount of productive citrus land almost in half from its peak, to 437,000 acres.

In Sarasota County, acreage in citrus has dropped from 1,684 in 2004 to 1,197 in 2015. The double whammy of increased competition from other beverages and greening’s upward price pressure reduced per capita consumption of orange juice in the U.S. from 5.8 gallons in the late 1990s to 3.1 gallons in 2014. Annual production of oranges in Florida, 242 million boxes as recently as 2003-2004, dropped to 81.6 million boxes last season, according to the U.S. Department of Agriculture, which last month released a dire prediction for the coming harvest—70 million boxes.

Some growers and industry experts see these numbers as signs that Florida citrus has reached a dramatically lower, long-term plateau, a much-reduced position in both the state economy and the national consciousness. Orange juice is no longer relentlessly marketed as a daily staple. Backyard citrus, which has been as decimated by the disease as commercial groves, is no longer a lure to Northern home buyers. And though citrus still contributes a total of $10.7 billion per year to Florida’s economy, it is nowhere near the powerhouse it once was, not dominant enough to warrant displays on license plates or welcome signs at the state line.

“There seems to be a sense of resignation in the industry that citrus greening is going to wipe out large areas of citrus production, and that the industry is going to have a much smaller footprint in the state,” says Alan Hodges, an agricultural economist at UF.

This view is based on the sense that science is years away from finding a cure, that no existing citrus varieties can remain healthy in the face of greening, and that the expense of replanting dead groves and dousing them with enough chemicals to remain productive has drained all the profit from the industry.

John Albritton, 26, a sixth-generation Sarasota County grower and cattleman, says his family is still holding on its citrus acreage, sticking to traditional methods and hoping for a cure. “Everybody has greening and there’s nothing you can do about it, so we just keep on farming,” says Albritton, whose family firm, Albritton Fruit Company, owns about 400 acres of orange groves and a store on Proctor Road. “We’re still making money on our fruit, and our doors are still open every day.”

Steve Melton, whose Hernando County family runs a diversified farming operation, says they’re likewise hanging on to their 100 acres of citrus, but they’re showering the leaves with frequent, direct applications of fertilizer and trimming the rows of trees like hedges.

“The idea is, the less canopy you have, the less nutrition the roots have to create to support it,” says Melton. “We have friends in the industry who have tried it and who have good results . . . but I’m not sure it’s even a break-even deal.”

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Fred Gmitter, a professor of citrus breeding and genetics with UF, stands near a citrus tree at the Lake Alfred center. 

But the outlook is more optimistic in other corners of the state, including at UF’s citrus research center in Lake Alfred, a tiny Polk County town on the northern edge of the state’s citrus belt. The center, a compound of lab buildings and Quonset hut-shaped greenhouses surrounded by 600 acres of groves, is touted as the world’s largest agricultural research facility devoted to one crop. In recent years, most of its efforts have, in fact, been devoted to one disease—greening.

Over the last 11 years, the center has received large chunks of the funding available for greening research, including $8 million in the state budget this year, and nearly $100 million that Florida growers have contributed since the disease’s arrival. Researchers at Lake Alfred helped develop the pesticide and fertilizer regimens that can extend the life of infected trees. They have tried to fight the disease, with varying degrees of success, using antibiotics and heat exposure. And several teams of scientists are seeking the holy grail of citrus research, a genetically modified tree that could replace the traditional, vulnerable varieties such as naval and Valencia. Until recently, most scientists believed such a cure could be decades away, and even then would leave the industry facing a serious marketing challenging—selling what has been touted as nature’s perfect drink after it had been modified with genes from, say, a jellyfish.

But that was before the emergence of a gene-editing technology called CRISPR. The technology is based on a virus-fighting system in bacteria that relies on stored strands of DNA, called “clustered regularly interspaced short palindromic repeats,” or CRISPR. Bacteria use these strands—combined with gene-snipping enzymes—as part of a system that seeks out and destroys the genetic material in its viral enemies. In recent years, researchers have been able to turn CRISPR into a tool that can find and eliminate—or replace—genes in plants and animals. The process is touted as a potential cure for a wide variety of human maladies, and it is so much faster and more efficient than traditional methods of altering genes that it has been compared to the “find-and-replace” function of a word processor.

Not only does the editing go faster with CRISPR, researchers say, so will the regulation process. In a controversial and precedent-setting ruling in April, the USDA determined that a CRISPR-modified mushroom could go directly to market because, unlike traditional genetically modified organisms, it did not borrow genetic material from other plants or animals. That quality, growers hope, will also create a product that is palatable to customers.

“To knock out a specific gene without introducing a new gene would solve the challenge that’s facing growers and would be more acceptable for consumers,” Black says.

Nian Wang, a UF professor leading a team of a half-dozen CRISPR researchers at Lake Alfred, watched as one of them hunched over a desk in a lab the size of a walk-in closet, decanting a solution of RNA and enzyme from a pipette into a test tube holding dissolved citrus tissue. The RNA is modeled after genes in oranges. The idea is that the RNA will guide the enzyme to a targeted gene, where the enzyme does the cutting.

But as one example of the challenges Wang’s team faces—one that shows CRISPR is not as simple as the hype sometimes makes it seem—less than 5 percent of these RNA strands will find a gene to bond with. Another challenge: The vast array of genes in the citrus genome means that some are very similar, which in turn means that the RNA might lock on to a beneficial gene rather than one the researchers have aimed for.

“You have to analyze the genome carefully to make sure you target only the good guys and not the bad guys,” Wang says.

Before that can even happen, Wang’s team must identify which genes are, in fact, the “bad guys”—the ones that make the trees susceptible to greening. And then, towards the end of the process, comes the waiting that makes researching citrus more protracted than working with, for example, wheat or cotton. The crop is a tree. Years must pass before researchers can determine if it carries all the traits of a successful commercial product, especially the ability to bear attractive, tasty fruit. But even this process will be hastened by CRISPR, because it leaves researchers with a detailed map of the tree’s genetic make-up before it goes in the ground. And despite all the obstacles, says Wang, that crucial step is not far off.

“Come back in two or three years and I’ll show you a tree,” he says.

UF professor Gmitter can show off trees right now. Though he, like Wang, is conducting CRISPR research, he is also one of the few scientists who think the answer to greening may be in existing citrus stock. A team at Lake Alfred, he says, has married dozens of rootstocks with standard orange varieties, and several of the combinations are showing promising levels of greening tolerance. Driving in a Lake Alfred test grove, Gmitter pointed to a 22-year-old Sugar Belle tree, a mandarin variety developed before the arrival of greening and approved for commercial sale in 2009. Its fruit is as tasty as the backyard favorite, the honeybell tangelo, but it is so greening-hardy that Gmitter had to sort through several limbs to find a single mottled leaf. “As you can see, it’s a big, healthy tree,” he said.

In another grove, Gmitter looked about 50 feet down a row of young trees to a vibrant-green specimen that towered over its peers. “Bingo!” Gmitter said, exclaiming and identifying the tree. It’s a cross between mandarin varieties, already fast-tracked for commercial production, and named Bingo because it came up a winner across the board. “It’s early maturing. It’s seedless. It’s easy to peel. It’s got good color and good flavor,” Gmitter said, proving his point by removing the peel in two pieces and revealing a fruit that was already orange and sweet in October. It is smaller than some growers would like—about the size of a small plum—and was developed as a fresh fruit, meant to be eaten as is, in a state where 95 percent of the industry is devoted to juice production.

But if growers are willing to shift their focus, Gmitter says, mandarins could make a strong competitor for the niche created by the California marketers of small, lunchbox-friendly Halo and Cutie mandarins. And the Bingo has turned out to be a competitor that thrives without the exhausting chemical regimen required to help traditional varieties of citrus survive—at least for a while—the effects of greening.

“This was grown without any special pixie dust in the ground,” Gmitter said, looking up at the tree. It’s not only remained healthy while surrounded by diseased trees, but also, defying conventional thinking about existing citrus, it has so far resisted infection. “We’ve never detected any symptoms of HLB and we’ve never detected the bacteria that causes greening,” he says.

Black’s packing house is only 40 minutes south of Lake Alfred on U.S. 17, tucked behind the old railroad depot in the crossroads town of Fort Meade. This proximity has allowed him to treat the center’s researchers almost like local agricultural extension agents, seeking advice from them and helping them test their theories in what he calls “real-life” conditions. Black has set aside some of his land to test rootstocks developed at Lake Alfred and by the USDA. About 30 acres of the new groves he showed off had been planted in Sugar Belles, a variety he is well-positioned to sell because Peace River has a long history of shipping fresh fruit. And he is eager to try out a CRISPR-modified tree. But the main revelation of the tour of his groves east of town was that even without breakthrough technology, growers can make a profit.

Behind the wheel of his Chevrolet truck, Black looks as wholesome as his healthiest groves, a devoted runner who dresses neatly in jeans and short-sleeve plaid shirts. He emphasizes that Peace River is a family company, that he is a fifth-generation grower running a medium-sized operation, its 2,700 acres dwarfed by competitors who control more than four times as much. But he concedes that more of the state’s citrus industry will be concentrated among growers his size and larger and true “mom-and-pop” growers will be squeezed out by the investments required to fight off greening.

He stopped at one of his pump stations, which looked like a small town’s water works: 12-inch well pipe, pump powered by a 300-horsepower, yellow-and-green John Deere diesel engine, a solar panel to run the computer that regulates irrigation and the 30 or so doses of liquid fertilizer the groves receive per year. Those applications help bring the total cost of managing an acre of citrus to $2,200 per year, twice as much as a decade ago. The price of planting a new grove can reach $8,000. That’s partly because Black plants as many as 303 trees per acre, twice as many as he once did, with the expectation they will live half as long, about 15 years, before they succumb to greening.

“The management strategy is to aggressively grow these trees,” he says, “to produce a large tree that is capable of bearing an economic crop as quickly as possible.”

So far the 4-year-old trees he showed off were doing just that, yielding about 400 boxes per acre, about twice as much as a traditional grove of the same age. This allows him to capitalize on one of the rarely discussed upsides of greening: The lower production has pushed prices about twice as high, Black says, and his grove is turning higher profits now than during the peak production years of the late 1990s. “We see an opportunity,” he says. “It’s difficult and it’s expensive, but we’re in an environment with extremely high prices.”

He is just as upbeat about the industry’s future, just as well-armed with information to counter arguments from doubters. The accumulated environmental impact of all the chemicals needed to keep citrus alive? Actually, he says, the current, spoon-fed doses are taken up by trees at a far higher rate than the larger traditional ones. USDA’s forecast of a steep one-year drop in the harvest? It’s not all about greening, he says, but is mostly due to a fungus that kills flowers before they can bear fruit, and that spread last spring because of unusually heavy rains. The plunging demand? What growers have lost in the domestic market they can make up as wealth builds in countries such as China and India.

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 Shuming Wang, who works with the research team led by UF professor Nian Wang, agitates a sample after introducing strands of RNA inside a lab at the Lake Alfred center. 

Yes, he says, he misses the days when young growers could plant a grove and expect it to carry them through to retirement. Part of him wishes that he still saw regular television commercials for his product, and that glasses of orange juice were breakfast-table fixtures. “I don’t think we can ever recreate that,” he says.

But the high, sandy land between Clermont and Lake Placid is ideal for citrus and not much good for any other crop. Per-acre yields are bound to improve; abandoned groves will be reclaimed.

“I am very confident this industry can grow,” Black says. “I think it could be larger by multiples of two or two-and-a-half. We could easily be a 150- to a 200-million box industry in Florida again.”

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