Q.Is My Magnolia Dying?
My Magnolia had a beautiful floral display earlier in the year but now the leaves are turnng brown and falling off. There are lot of seemingly dead branches and just one small area where there is new growth. the tree was planted about 20 years ago and has never before been affected like this. we have several times in the past enjoyed a second floral display after the first had died back. There are several other trees in our area which are not showing the same problem. Regards Peter Byrne p.byrne3@sky.com

Certified GKH Gardening Expert
This is going to be a type of root rot. It will be difficult to say which, but that discoloration at the base of the tree points to a root infection.
I can't see the base well enough to establish what disease the tree has, and unfortunately, some of the more harmful fungi are not treatable.
I would advise contacting your local extension service. They may be able to help you address the issue.
This link will help you to find the closest to you: