I'm assuming it's the citrus greening disease

from the article, which is quite thorough IMO , indirectly it seems you were right but like what killed this pack a day smoker, cigarettes or lung cancer ?

I think they killed it themselves, with chemicals. That’s a fact,” Gunther said. In my time in Florida, I’d found a more complicated story, but down here, everyone had their theories, their longing for citrus nirvana, and their anger at the loss.

“They sprayed so much chemicals, the damn grass don’t even grow here anymore—you can quote me,” Gunther said. “I knew it back in 1990. I said, ‘They’re sprayin’ so much chemicals it’s gonna be the end.’ And it’s the end.”

the argument seems to be they so weaked the trees by over application of chemicals, that a disease was inevitable.

A warning take that will be ignored, like climate change.. we've emitted so much CO2e, we'll collapse civilization. You can offshore orange production but not civilization.