Q.Magnolia Tree ( Pink Tulip) Approx 25 Years Old, Always Been A Picture Until Now.
It produced less flowers this year and the leaves are beginning to fall. Clearly they have a disease. Could you advise me on what it is and any treatment please. The tree is enormous so a spray gun is not possible. It gives us wonderful privacy so am very concerned we may lose it . Thank you in advance of any advice. Regards Sue

Certified GKH Gardening Expert
This can be common with wet soils, unfortunately. Fungal and bacterial infections in large trees can be treated with SYSTEMIC fungicides. These will be watered into the soil and taken up into the tree. It may help to keep any fallen leaves out of the area, as well.
These articles will help:
https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-tree-diseases.htm
https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-tree-care.htm