Citrus Greening Disease aka "Huanglongbing" while not viral, but bacterial, reminds me of COVID 19 in humans...causes a "Pneumonia" like illness in citrus with "re-greening" rotting of fruit, and eventual death of trees. The disease is vectored and transmitted by the Asian citrus psyllid. Infected trees can be treated with antibiotics...a crazy citrus disease!
https://en.wikipedia.org/wiki/Citrus_greening_disease