Florida citrus growers plant gene-edited trees to fight citrus greening

EPA approved CRISPR-designed CarriCea T1 rootstock earlier in 2026

Florida citrus growers are planting new trees that have been modified using gene-editing technology to ward against citrus greening, the bacterial infection that has killed off many of Florida’s citrus trees since arriving in 2005. Growers have tried everything from tents to sprays to protect trees from the disease, which attacks their immune systems and has no cure. They are now waiting to see whether the EPA-approved genetic modifications will keep the trees alive.

Citrus greening arrived in Florida in 2005 and is spread by a tiny winged insect called the Asian citrus psyllid. Once the insect infects a tree, the bacterium attacks the tree’s immune system, leaving it unable to fight the infection. Infected trees produce bitter, discolored fruit and usually die a few years later.

Before the disease arrived, Florida growers were shipping around 300 million boxes of citrus each season in the late 1990s, according to Matt Joyner, CEO of Florida Citrus Mutual, a trade association that represents growers. By comparison, the state shipped a little more than 15 million boxes during the season that ended in June, Joyner said.

Ron English’s family ran a citrus business in Valrico, Fla., for generations until greening wiped it out, forcing the operation to close in 2015.

“We had some of the best looking groves around, and all the time and effort that we had spent, you just see it diminish right before you,” English said.

Tampa-based Soilcea used CRISPR gene-editing technology to design a rootstock that resists greening. Known as CarriCea T1, the rootstock keeps a tree’s immune system working, allowing growers to rely less on insecticides. The Environmental Protection Agency approved the rootstock earlier this year.

Soilcea CEO Yianni Lagos said the root system is where the fight has to start: although the first visible sign of infection is yellowing leaves, “before you even have symptoms, half the root system is already dead.”

Lagos is now waiting to see what happens when the CarriCea T1 rootstock is grafted onto trees and planted. In a Soilcea test field, results so far are promising — trees grafted onto CarriCea T1 are taller and greener than unmodified trees planted beside them.

English cares for the dozens of test trees that carry the modified rootstock. They were planted last summer beside trees without it.

“That’s the CarriCea rootstock — see how big the leaves have filled out,” English said, pointing to a tree with the modification. The smaller tree next to it, without CarriCea T1, has yellower leaves. “See the discoloration, that’s the disease already working through the tree,” he said.

The real test for CarriCea T1 will be the fruit itself, which takes years to appear — not only how it grows but also how it tastes.

“The data suggests it’s gonna work, but until you have a 10-year-old tree, you don’t know how the tree is going to perform,” Lagos said.