This 30-year-old tree named Donaldson may be researchers’ best shot at rooting out the deadly disease decimating Florida’s citrus trees — why they believe studying it may prove fruitful

Meet Donaldson

Florida was once bursting with orange trees, but today, Donaldson is the unassuming survivor and may be the industry’s best shot at bouncing back.

What makes this tree stand out comes down to three traits: it’s a genetically pure orange, it produces sweet, high-quality fruit and most importantly, it’s shown resistance to citrus greening.

Florida’s signature orange juice used to rely mainly on just two varieties — Hamlin and Valencia. In a search for solutions, Mattia tested more than 25,000 trees for both disease resistance and fruit quality. Many trees survived the disease but produced bitter, unusable fruit. Donaldson, however, delivered both resilience and sweetness — exactly what Florida growers need.

But disease isn’t the only threat squeezing the state’s citrus industry. Rapid development, devastating freezes and a string of powerful hurricanes — from Irma in 2017 to back-to-back storms in recent years — have battered groves and left farmers struggling to rebuild.

As a result, Florida's citrus acreage has shrunk from over 832,000 acres at the turn of the century to about 275,000 today.

It’s become such a tough business that Alico — one of Tropicana’s major suppliers — has decided to exit citrus altogether. John Kiernan, CEO of Alico, said in a statement, “Growing citrus is no longer economically viable for us in Florida.”

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Saving the industry

Mattia isn’t hoarding the Donaldson tree’s potential for his own team, even though the USDA currently keeps the prized tree under lock and key. He says the state has already propagated 18,000 Donaldson trees and is distributing them to growers statewide to speed up the comeback.

“We’re pushing it out to commercial usage,” he said. “If people want to test it in their own grove, it’s available, and we have the data and the research going on here that supports that effort.”

Mary Graham, who runs Graham U-Pick Farms, knows firsthand how devastating citrus greening can be. She’s tried everything from adjusting soil nutrients to cutting back on chemicals, but the disease often has the final say. Still, she’s not throwing in the towel just yet. Graham is eyeing new seedlings for her children to care for one day.

“We’re hopeful about the Donaldson tree,” she told WFTV 9. “With that one, what else can they come up with?”

While the future of Florida’s orange juice is still uncertain, Mattia is staying optimistic. Even if Donaldson falls short, he’s determined to find a blend of citrus that keeps the juice flowing.

“My mission is to really help people,” he said.