Hi Kim,

I'm sorry to hear about your apple trees.  From what I can see in the photos, it does looks like you're dealing with fire blight, a common problem in our area.  While difficult if not impossible to eradicate, a few things could help slow the infection, including pruning out the diseased portions (with a wide buffer between the symptomatic portions and the pruning cut), reducing water/fertilizer long term (since succulent growth is particularly susceptible), and some chemical treatments, which would need to be applied by a licensed professional.

These CSU Fact sheets address fire blight and cover details of treatment options and disease life-cycle information.

https://csfs.colostate.edu/wp-content/uploads/2024/01/Fire-Blight-Fact-Sheet-2.907.01.pdf

https://extension.colostate.edu/docs/pubs/garden/02907.pdf

I hope this is helpful!

Cordially,

John