The disease was found at a garden centre in Porto Cristo, the first finding of the disease in Spain.
There is now a movement ban on cherry trees and oleanders within a 15,000 hectare area of the find.
Two more infected cherries have since been found. They were imported from Catalunya in 2012.
Xylella first became a threat publicly acknowledged by the UK authorities in early 2016. The disease has yet to reach the UK.
The HTA said it understood EU rules are being enforced and expects further information next week as there was an EU standing committee on plant health this week.