I have a 10 year old Southern Magnolia which is failing to thrive?
Southern Magnolias are a fantastic tree, but need to be grown in certain culturally correct conditions.
There could be a couple issues that need to be addressed: Prescription Soil Sample, Structural Pruning, Root Collar Excavation, etc.
Make an appointment to have an arborist conduct a free property inspection for you and give you a better idea of whats going on with your Southern Magnolia.