I have talked to three certified arborists about my 19 yr old crabapple tree which has fire blight and I have received 3 different treatment proposals. The only commonality is winter pruning. Some suggest antibiotic treatment and others say it doesn't do anything and yet another suggested a cambistat application. I'd love to hear form the extension office and get your recommendation on how to treat the tree? apart from pruning can I do any of the other treatments myself?
Douglas County Colorado
Here is the link to the CSU Douglas County Extension Office Fact
sheet on fire-blight for crabapple trees. There is a section that talks about management and possible treatments. Hopefully this fact sheet answers your questions and provides you with solutions you can do.