Citrus Greening: Florida’s Quagmire
By Michael Salazar
Dr. Tim Shubert, agriculture pathologist for the Florida Department of Agriculture
(FDA), estimates that if a cure to citrus greening is not found then Florida‟s annual $9.3 billion
dollar citrus crop will not exist within two-to-five years. Mark Estes, regulatory director for the
FDA calls citrus greening a “quagmire for Florida.” There is currently no laboratory culture to
even begin to try to understand citrus greening disease.
Citrus greening is a bacterium known as huanglongbing (Translated: Yellow Dragon
Disease), or HLB. Once a citrus tree is infected there is no known cure for the disease. HLB has
become the most serious citrus disease in the world. The pathogen existed in Asia in the 1800‟s.
In 2005 the U.S. Department of Agriculture confirmed HLB in South Florida. They could not
identify the source plant or plants. FDA officials speculate that an infected citrus plant carrying
infected insects was illegally brought into Pam Beach County, Fla.
Asian and African psyllids are the primary carrier of HLB in Florida. There are many
different kinds of psyllids, commonly known as jumping plant lice. These insects can be found
throughout the world. Some psyllids can do extensive damage to crops, but most psyllids are
considered benign.
Psyllids feed from plants by sucking the sap. The HLB positive Asian psyllid feeds only
from citrus trees. Dr. Shubert calls that “host specific.” The Asian psyllid acts as a carrier or
“vector” of HLB. When it feeds from a citrus tree it is actually inoculating the tree with the
disease.
When other psyllids feed from infected trees they then become vectors for HLB and
spread the infection to other tress as they feed. It is an open cycle that repeats itself each time a
psyllid feeds on any variety of citrus. One infected tree can spread HLB to an entire grove.
The mandarin orange is a preferred citrus tree, but psyllids will feed on any citrus tree
available to feed and breed on. Once infected it takes somewhere between two and six months
before citrus trees begin to show symptoms of citrus greening. Citrus greening can be recognized
by a particular leaf yellowing and blotchy, mottled leaves. Once infected, the citrus tree will die
in approximately two years.
Some commercial citrus growers have tried to use nutrition enhancers like special
fertilizers and even plant-like steroids. While they have experienced an extended life of some
trees the trees still eventually died from the pathogen. Arguments have even been made that
trying to extend the life of an HLB infected citrus tree only lets more psyllids feed to further
extend the damage to other healthy trees.
As with Citrus Canker, the former Number One enemy to Florida‟s citrus cop, the FDA
has enacted a very aggressive campaign to identify and remove infected trees. But with all the
programs to combat HLB, citrus greening now has been positively identified in all of Florida‟s
34 citrus producing counties. Chemicals and oil sprays have had no effect to combat the spread
of HLB.
The FDA and orange growers have spent $26 million dollars on research but have yet to
yield positive results. Ongoing education, cutting down identified infected trees and judicious
use of pesticides have been tried. But some officials in the citrus industry have concerns if it‟s
too little too late to save the citrus industry.
Melbourne‟s Communal Horticultural Agent for the FDA, Linda Sears, said that Estes‟
“quagmire” assessment is accurate. She compared citrus green to the last space shuttle launch.
“We knew HLB was coming, just like we know the shuttle was ending. In both situations we‟ve
been caught in a replacement gap.”
Sears explained that without an HLB culture to research the best thing that they can do is
develop HLB resistant citrus. “It would take five years to research and another 10 to 15 years to
see a commercial producing tree,” she said.
Researchers around the world have been stymied to come up with a way to eradicate
HLB. Organic methods using insects to attack and kill the Asian and African psyllid has
produced no positive results.
Chemical treatment to eradicate the psyllid has proven elusive.
“HLB spells fear for a lot of growers and home gardeners who immediately react with
chemicals. But by the time HLB is identified in a grove it‟s usually too late. Plus, the overuse of
pesticides is thought can wipe out entire colonies of beneficial insects; bees for example,” Sears
said. “Cutting the tree down the moment it‟s identified is the only real way to make sure the
psyllid won‟t feed from it.”
Dr. Shubert echoed similar sentiments of Sears and he added that with no hope of an
HLB cure it might be another 10 to 12 years before the world begins to get a grip on the disease.
But by that time the economic cost will be enormous.
“Florida‟s led the way for a long time when it comes to innovative and practical
techniques and methods to get the best yields for our citrus crops. Our growers have all been
united when it comes to making Florida the leader in citrus research. So the HLB is a
disappointing climax to such a successful and historic Florida business,” Schubert said.
FDA regulator Estes sees HLB on a visceral level; laws cannot regulate psyllids. “The
billions made off oranges is a from a market report. It does not include ancillary costs,” he said.
“Think about what it cost to get an orange to market,” Estes added. “Labor, production,
fertilizers, fuel, energy, shipping, it goes on. The orange is a key factor to what made Florida
what it is today; look at any Florida license plate and what do you see in the center of that plate?
Now think of no more oranges in Florida in the very near future. It‟s a quagmire.”
HLB is also affecting the home gardeners. At 9:30 a.m on April 24, 2010 Channel 13 on
the Bright House network reported that because of the spread of HLB there is a movement to
restrict the private ownership of citrus trees.
“That‟ll never happen because we will have lawyers this time,” said Victor Davis, a
longtime Melbourne resident and owner of many fully mature citrus trees. “When we got hit with
citrus canker the city came around and cut down any trees that they said had canker. They said
that it was done to help the commercial growers. And then look what happened. Suddenly citrus
canker is considered „no big deal‟ to the commercial growers. It takes 20 years to get a good tree.
We home citrus growers did our part already.” He took time to finish what he wanted to say.
“Look. What really happened is that Florida‟s banked on the orange for a long time. Well, that
worked before, but not anymore. The Florida Sunshine State is losing the orange to a bug!”
When questioned about possible solutions to citrus greening “diversity” was at the top of
the every one‟s list. Those interviewed all agreed that diversity in the kinds of citrus trees and
other fruit crop we now grow needs to happen. Avocados, peaches, nut trees, and more need to
be planted now.
“There‟s a wide variety of harvestable crops that could do well in our environment,”
Sears said. “We need to have a harvest that is relevant, gainful and marketable. If we don‟t do
that now then every day we don‟t plant a marketable crop is that much time wasted, and that
much profit lost.”
Davis spoke of the past when he referred to the citrus replacement. “Cotton was king
here. Grapes were Florida‟s first crop. Corn was the staple. Right now they‟re developing
different kinds of seeds for gas. If we lose oranges then we need a fuel crop like corn to make
ethanol and other viable energy sources. With the housing market so bad at this time we might
think about using the land to make wind power with wind mill generators.”
“We see this coming and we have to agriculturally diversify, now,” Estes said. “If we
don‟t then there are countless jobs that will just dry up. The restaurants and stores that cater to
drivers, pickers, and producers will lose their customers. We have to bring in crops that we can
sell.”
With HLB such a potential disaster the natural question is why isn‟t the issue of citrus
greening at the top of Florida‟s headlines? Why is no public outcry or public demands for
hearings to address the citrus greening problem?
“It‟s tough,” Sears said. “Because Florida looks so lush, the idea of no more citrus trees
here is unthinkable. So they don‟t think about it. Others who live here don‟t want to think about
the possibility of losing an icon. The orange has always been here, right?”
Dr. Shubert put it another way. “The national and world news has not been very good
lately. People seem to be tired of hearing bad news so they just turn it off on television and in
their mind. It‟s refection of society in general. People forget where the fruit comes from. When
they go to the supermarket and pick up a bag of oranges they have no connection to who
produces the fruit, the trees, or land itself. Without the public‟s support it‟s a major setback for
research to try to resolve our hopes.”
However it is called, Huanglongbing, HLB, yellow dragon disease, citrus greening
appears to be unstoppable. World-wide HLB has destroyed the citrus economy in many places
already. If Florida‟s citrus crop succumbs to HLB it will be almost another generation before
oranges are part of the state‟s economy again. Agricultural diversification may help commercial
produce growers and home gardeners. But today they may be tending a dying generation of trees
that made Florida famous.