I have this Pyracantha that keeps on getting brown tips and wilting of the leaves that eventually lead to branch die back as well. This tree used to be full but have died back more than 50%. I think this is fire blight but I am not sure. This has been going on for over 2 yrs and have killed a few good branches. I repotted last yr but didn’t help much. spray of anti fungal and bugs overall hasn’t helped but stopped spraying for several months now since leaves are fragile.
Am not sure it’s fireblight as the browning is starting in the leaf tips rather than the branch tips, but that is a common culprit in pyracantha. Sending a sample to a lab (some university agriculture departments will do this for free) is a good way to identify the pathogen.
Blights are hard to control once they are in the system. From what I’ve seen, pyracantha drop branches like this when there are pockets of old soil or when they’ve been exposed to the pathogen. Keeping the tree as healthy as possible - no over-watering, no bonsai work, no fertilizer - is the best course of action until symptoms clear up.
Here is some info on fire blight: https://www.planetnatural.com/pest-problem-solver/plant-disease/fire-blight/