Disease devastates Florida’s citrus industry

Families abandon generations-old farms and packing houses close as citrus greening cuts state production by 75 percent

ORLANDO, Fla — Florida’s citrus industry will never recover from a devastating disease that is wreaking havoc on fruit trees around the world, says a breeder.

Citrus production in the state is about one-quarter of what it was at the turn of the century, primarily due to Huanglongbing disease, which is more commonly known as citrus greening.

The disease turns fruit green on the bottom and deep orange on top, causes it to fall off the tree before it is ready to eat and makes the fruit taste bad.

Florida farmers produced 83 million boxes of citrus in 2018, down from 298 million boxes in 2000.

Fred Gmitter, professor with the University of Florida’s Citrus Research and Education Center, believes production has bottomed out but citrus greening disease has already inflicted permanent damage on the industry.

“Bottom line, we will never be back to what we were before this disease came to Florida. Never,” he said.

Citrus greening was first discovered in the state in 2005. It is now found in every grove in Florida. Older groves are 100 percent infected.

“This disease slowly kills trees. It is not an instant death sentence,” he told delegates attending Bayer’s AgVocacy Forum.

It has rocked a $10 billion industry. Families that had been in the citrus business for five generations have walked away from their farms.

Packing houses have closed. There are only a handful remaining in Florida.

There are no natural forms of resistance because it is a new disease, so the onus is on breeders to come up with something.

The problem with that is citrus breeding is a painstakingly lengthy process. It can take 25 years to release a new variety.

It takes another five to seven years before a new release starts producing as a commercial tree.

One tool that may help speed the process is gene editing. Researchers are studying about 2,000 target genes in an attempt to find the one that makes citrus trees so susceptible to the disease.

Once they discover the gene they can use gene editing to modify it, making the tree resistant to citrus greening.

But that would still require a few years of greenhouse testing, followed by about five years of field trials. Farmer uptake might be slow at first and then there is the time it takes to ramp up production.

So there is no quick fix.

Lynn Dornblaser, director of innovation and insight at the market research firm Mintel, had some advice for Gmitter if researchers decide to go the gene editing route.

She said it is imperative that researchers, growers, packers, food companies and anyone associated with the citrus industry be transparent and clear with consumers about what they are doing and why they are doing it rather than just throwing out the term gene editing.

“To a regular consumer that sounds like a horror movie,” said Dornblaser.

“I can’t imagine that anyone would be accepting of that. I mean, genetic modification was hard enough. Gene editing sounds 100 times worse to consumers.”

A “dream” solution to the citrus greening nightmare could come from a citrus virus that researchers have disarmed.

If researchers are able to isolate the right gene and re-sequence it so that it makes trees resistant to the disease they could put that construct in the virus, infect the existing trees and cure them.

In the meantime, there have been some agronomy techniques related to fertilization and how to feed a compromised root system that are showing some promise at reducing the damage caused by citrus greening.

Groves that were producing 100 boxes of citrus per acre are yielding 300 boxes by applying some of the techniques. But that is still half of what they used to produce.

“It’s a stop-gap measure. It’s not a cure,” said Gmitter.

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