This is one end of one branch of an otherwise perfectly heathly-looking apple tree. I've recently acquired this garden so IDK the history. What is this disease and what should I do?
Sick bit https://www.flickr.com/photos/54992580@N06/7264259500/in/photostream/
Healthy bit
https://www.flickr.com/photos/54992580@N06/7264261294/in/photostream/