Narrator: In 2021, Florida had its worst orange crop
since World War II.
That's because this insect is waging a war
on the state's valuable citrus trees.
So this tree is infected with citrus greening.
It produces small, misshapen fruit.
Just see the difference.
This disease can be a tree killer.
Narrator: The insect spreads a disease called HLB,
or citrus greening, and it's infected
nearly every citrus grove in the state.
Tripti: Less canopy, you can see there's
just less foliage on the tree.
You can see through the tree.
Narrator: The oranges are still edible.
The real problem is that citrus greening has slashed
Florida's production by 78%.
It's cost the state nearly $8 billion
and driven many growers out of the industry.
Fred: You should go back in your mind 15 years
to what this place once was as a collection of varieties.
This was full of beautiful green trees.
Larry: We've had freezes, hurricanes,
but citrus greening has definitely been
the most challenging issue we've faced in my career.
Narrator: This group of scientists is racing to find
a cure, armed with some unique weapons.
Lauren: This is about the size we're going to put
on most new trees now.
Narrator: The researchers have helped growers produce
oranges on the infected trees,
but they haven't found a long-term solution yet.
We will have to live with the infected trees
and just make the most out of them.
Narrator: So can they keep this disease at bay
before it wipes out the state's orange industry?
We head to Florida to find out.
Larry's a fifth-generation farmer in Fort Meade, Florida.
Larry: We've been growing citrus in my family since the 1850s.
When I first started in the industry, citrus occupied
over 900,000 acres in the state of Florida.
In fact, some years we had too much fruit,
and market prices were depressed.
Narrator: Just 15 years ago, his family packed
a million orange cartons a year, mostly Valencia oranges,
the big, sweet, juicy kind.
You planted a grove expecting that to last
for multiple generations.
Narrator: The first case of citrus greening was reported
in China back in 1919.
It quickly spread across the continent, devastating
citrus groves in India, and Saudi Arabia as well.
No one knows exactly how the Asian citrus psyllid made it
to Florida, but in 1998, it showed up
on an orange jasmine plant in a backyard
in Palm Beach County, and it quickly spread
throughout the state on infected rootstocks.
But it would take another seven years
before Florida's orange trees showed signs of greening.
It spreads throughout the state
before you even know it's present.
Narrator: And in 2005,
Larry found his first infected tree.
Larry: It was a real challenge and eye-opening for us.
We knew what a threat it could be to our operation,
and we were fearful there were more infected trees
that just had not been detected.
Narrator: At first, Larry tried removing
all the sick trees.
But the insect moved faster,
soon infecting too many to control.
When a psyllid munches on a citrus tree,
it leaves behind the bacteria that causes greening
here in the vascular tissue.
The bacteria replicates
and blocks this important highway for moving nutrients.
Underground, the root systems thin and die out.
Above ground ...
Larry: You notice the yellow pattern,
the dark green spots.
Tripti: If you can see me through the canopy of this tree,
that means this tree is really, really sick.
Narrator: While the trees do keep bearing oranges
for a few years, the fruit essentially never ripens.
Larry: You see it's small in size.
It remains green, and when I cut this fruit,
you see an odd shape.
Narrator: You can still eat the fruit.
It's just not as sweet.
The orange juice from this fruit has lower sugar content,
or Brix, than normal fruit,
but there's nothing wrong with the juice.
(laughing) But it's awful.
Narrator: And 40% of those oranges fall off the tree
sooner than usual.
Michael: The bacteria is actually starving
and kills the tree over time.
Narrator: Today, researchers estimate 90%
of all orange trees in the state have the bacteria.
Larry: No longer do you see citrus trees
abundant in the landscape.
Narrator: Larry has kept his trees alive and producing
for 15 years using a combination
of horticultural techniques developed
by scientists at the University of Florida.
Some of our work that is going on right now
is finding ways to keep those trees that do have
the disease still producing fruit that are usable.
Do you guys want to see what some psyllids look like?
All right. So they're very small.
Ooh, there's an escapee, actually.
They're small.
They kind of jump around a little bit.
So we use this thing called an aspirator,
or the more fun term we use with children is pooter.
We just suck them up.
It's basically a little vacuum in my hand.
Narrator: Here, Lauren Diepenbrock can study
the psyllids' movement to learn
what might keep them off a citrus tree.
Lauren: Using an aspirator is actually a really efficient way
to collect psyllids.
Narrator: She's figured out a few things
that detract psyllids. First, this pink clay.
It's sprayed on the trees to hide the leaves
from the insect, which uses light wavelengths to see.
One study showed the clay was more effective
than insecticides.
The second thing Lauren is researching is
these 8-foot-wide sheets of plastic,
called reflective mulch.
Lauren: The idea is that it should make it
where the psyllid can't find the host plant.
It could be that it blinds them
or causes a visual deterrent.
Producer: Has it worked?
Lauren: Uh, somewhat. (laughing)
We do get psyllids.
We do get them, but we do get them at a reduced rate.
Narrator: A few years ago, farmers discovered
that putting plastic bags around baby trees could help them
grow stronger before infection.
Lauren's now studying how effective
these individual protective covers,
or IPCs, actually can be.
Lauren: So this is IPC mesh, and as you can see,
there's little holes in it.
You can see my hand very clearly.
Wind, sun, rain, it all gets through here.
The goal is to really keep that Asian citrus psyllid
off the tree. And then if you look underneath,
this is our irrigation.
Narrator: The baby trees will grow
in the IPCs for two years.
Lauren: So you can see the trees aren't perfect.
They're still going to have some stuff on them.
We do have some pest issues in here, but you know,
they look really good compared to what's in the open field.
And this will actually give our trees a fighting chance
once they're out in the environment,
and they could potentially get infected with CLas.
Narrator: Scientist Tripti Vashisth thinks
the key is in the soil.
Tripti: We have been learning that the trees need
these nutrients to fight infections.
The citrus trees, because of this disease,
have very small roots, or fewer roots,
so they're not very efficient in picking up the nutrients.
It's like a job of 10 people needs to be done by one person --
same with the roots.
Narrator: She figured out that giving smaller doses
of fertilizer and water more frequently
helps the sick roots absorb nutrients better.
Tripti: And it's similar like six small meals each day,
rather than three big meals are better.
Same as with the fertilizer and irrigation.
Smaller doses are better than big doses.
Narrator: Larry uses fertilizer custom-designed
for his trees.
He's also planting more young ones.
Larry: One of our strategies for dealing
with greening is to plant the groves at higher densities.
We're planting 300 trees per acre,
compared to 140 to 150 trees per acre
before we were dealing with the disease.
Narrator: So if he knows all the trees will get infected,
with more planted, hopefully some will survive.
Growers have also tried releasing predator wasps
and spraying insecticides.
While there's no silver bullet, in combination,
these short-term solutions have sort of worked.
You can slow down the decline.
Larry: We've been battling citrus greening for 15 years,
and while the industry's not thriving,
we're definitely surviving.
Narrator: But the problem is all these approaches tack
on an extra $600 per acre onto production costs for growers.
Larry: Our revenues are down by more than half
on an individual grove basis.
Fred: Growers are losing money.
Narrator: And many couldn't swallow the losses.
By early 2022, half of Florida's orange growers had left
the industry.
So while he waits for a long-term solution,
Larry's taking the hit so he can keep harvesting
the same way his family always has.
Workers quickly pick the oranges and drop them into bags.
Once they've got a good batch, pickers dump them
into baskets in the grove.
Workers then truck the oranges to the packing facility
just down the road.
Larry: We have eight digital cameras that takes a picture
of each piece of fruit as it travels
through the packing line.
We use an electronic sorter to divide the crop by color.
Narrator: If they're orange enough,
the fruit gets cleaned and hit with a layer of natural wax.
Larry: That preserves the fruit, extends its shelf life.
Narrator: Today, because of HLB,
Larry packs half as many boxes as he did 17 years ago.
If the oranges are a bit too green,
Larry knows they'll be hard to sell on the fresh side,
so he sends them to get juiced
at the Florida's Natural plant in Lake Wales.
Larry owns the juicing plant along with other local growers
as part of the company's cooperative.
Jude: About 90% of the fruit grown in the state goes
to orange juice.
Narrator: But just like growers,
the factory has been getting fewer oranges.
Dave: So less efficiency in the plant.
Narrator: With a lower fruit volume,
the factory had to shut down one of three processing lines.
Nowadays, 60,000 boxes of oranges arrive at the plant
from cooperative farms across central Florida.
That's about 30,000 fewer than before HLB.
Dave: Within 24 hours of harvesting, we juice the fruit.
Narrator: This machine squeezes the juice
out of every orange.
Dave: We pull out any seeds,
and we also collect the pulp, where we can add that back
to whatever degree we want to do that.
Narrator: The juice gets pasteurized
and then pumped into cartons.
But remember, greening affects oranges' natural sugar content,
so Florida's Natural has to blend infected oranges
with sweeter ones from different regions or even seasons.
It still tastes like orange juice.
It's just not quite as sweet.
Today, the factory pumps out
about a third less than pre-greening.
Dave: They need a home for their fruit where they can get
maximum value, that hopefully can sustain their operations
until a solution to greening is found.
Narrator: Many scientists believe
the long-term solution lies with reengineering nature.
Either genetically changing the bug itself,
or naturally breeding citrus trees.
Larry: Ultimately, a tree that's resistant or tolerant
to the disease will be key.
Narrator: That's the project Fred Gmitter
and his team are working on at the University of Florida.
They're trying to breed for an HLB-resistant orange variety,
meaning even if the disease shows up,
the tree won't get sick.
To do that, he takes two different types of trees,
maybe one with yummy oranges and one that's resistant,
and essentially has them mate.
And their kid will hopefully still taste good,
but won't get HLB.
Michael: That's really the holy grail of citrus greening research.
Narrator: But that's not easy.
Finding a resistant orange is like looking
for a genetic needle in a haystack.
It's extremely difficult to breed new oranges.
We know of some kinds of trees related to oranges
that are resistant, and we're trying to access
the genetics of those resistant types by making crosses.
Narrator: Fred says it could take more than a decade.
Fred: So it's long-term. There's always an element
of serendipity in this.
Narrator: But armed with that miracle resistant tree,
they could be better prepared to tackle future diseases.
Fred: It's a global, interconnected world we live in.
People and plant diseases move about pretty freely,
and so there will be another problem,
another disease come along.
Larry: I believe science will continue to deliver new tools
that will make growing citrus easier over time.
I look forward to those days.
I'm sure we'll have other challenges that we'll face
in time, but today, citrus greening is here to stay.