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In Florida, oranges are so important, they're on the state's license plates, but this year's orange crop is expected to be the smallest in more than 50 years. The problem is citrus greening, a disease that ruins fruit, kills trees and is now threatening the survival of Florida's signature industry. But NPR's Greg Allen reports science is giving growers reason to hope.
GREG ALLEN, BYLINE: Fred Gmitter at the University of Florida is one of the researchers working to find a cure for citrus greening.
FRED GMITTER: Where we're walking through right now, I think you see a lot of reasonably unhappy trees.
ALLEN: Right - a lot of dead branches.
GMITTER: A lot of greening symptoms.
ALLEN: Gmitter has worked for 30 years at the Citrus Research and Education Center at Lake Alfred in Central Florida to develop new varieties for citrus farmers. We're walking through one of the center's research groves, where many trees are clearly hurting.
GMITTER: But you look up ahead there on the right and...
ALLEN: I can see it.
GMITTER: You can see it (laughter).
ALLEN: Yeah - one tree that's full of fruit and looks very healthy.
It's a small mandarin orange variety called Bingo - seedless and easy to peel. It's a fruit Florida growers think will help them compete for market share with clementines from California and Spain. Gmitter picks one from the tree.
GMITTER: I wish the people...
ALLEN: He's peeling it here.
GMITTER: ...On the radio could smell this as I'm peeling it. Have a taste.
ALLEN: That is delicious.
Sweet, tart, tender and from a tree that after nine years is still healthy, despite being infected with citrus greening. Many Florida growers are excited about this new variety. Some 150,000 trees are on order, and many are already in the ground. The director at Lake Alfred, Michael Rogers, says progress in research - and with new varieties like Bingo - have sparked optimism in an industry in which the days once seemed numbered.
MICHAEL ROGERS: Because back in 2005 when the disease first showed up in Florida, we all said, OK, in 10 years, this is a death sentence, and in 10 years, the industry will be gone. Well, we're not gone, and we're going to hang on. We're going to keep going.
ALLEN: But Florida's orange crop now is less than a third of what it was 20 years ago, largely because of citrus greening. It's a disease caused by a bacterium that constricts a tree's vascular system, shriveling fruit and eventually killing the tree. The bacterium is spread by a tiny insect, a psyllid. At Lake Alfred, researcher Arnold Schumann shows me another promising development.
ARNOLD SCHUMANN: So we can open up here.
(SOUNDBITE OF DOOR OPENING)
SCHUMANN: Let's just go ahead and walk down - walk down to some of these narrow rows.
ALLEN: We're inside a large, screened enclosure filled with orange and grapefruit trees. This one-acre grove is two years old and already producing fruit. Schumann says the screened enclosure has shown grower's a way to protect citrus trees from greening.
SCHUMANN: It's been a hundred percent successful so far of excluding the psyllid and the disease in two years from here. So we expect it to be a long-term protection system that works.
ALLEN: One of the first growers to try it is Ed Pines. He's planted 20 acres of oranges in Lake Wales in screened enclosures. Pines says growing under screens is an option now just for farmers who raise fruit that's sold fresh in supermarkets and farm stands because it requires a big capital investment. That leaves out Florida growers whose crop goes to orange juice. But Pine says for him, the new developments have brought back the joy of raising Florida oranges and grapefruit, something that's been missing in recent years.
ED PINES: For me, going through a grove was like - I don't want to say therapy, but it was - it wasn't even work. It was awesome. Greening started - every time you go through a grove, you come back, and you're like - you get - you know, your stomach hurts. You get headaches. You stay up at night.
ALLEN: For growers, some of the best news in the battle against citrus greening is coming not from groves, but from research labs. Using the gene editing system CRISPR, horticulture scientist Fred Gmitter and other researchers are working to develop citrus varieties resistant to the disease. Gmitter says they're identifying targets on the orange genome they can manipulate.
GMITTER: And hopefully that's a gene or those are a group of genes that will make the plant no longer develop disease.
ALLEN: Using CRISPR technology, researchers have already produced plants resistant to another disease, citrus canker. The work here has led many in the industry to hope a long-term answer to greening may now be in the pipeline. Greg Allen, NPR News, Miami.
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