Apple Tree fire blight
You did not send a photo so you need to read this publication thoroughly. Check symptoms of your tree with those in the article. http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/fire-blight/
If you still believe you have fire-blight then follow the instructions carefully step-by-step. Sanitation is extremely important to any pruning tools must be sanitized after each cut by dipping in a solution of 1 part bleach to 10 parts water.