Answer: The fact that new leaves are opening with the brown patches eliminates a fungal leaf spot as they almost always show up on older leaves. Magnolia is native to your area an survives quite well with a few problems.
Have you sprayed the tree with anything, or used a herbicide near it? If not, I suspect the cause could be environmental (such as dry winter winds) or due to some other passing problem. It should correct itself soon. If not, you may want to contact your County Agricultural Extension Office (ph# 606/744-4682) and inquire about how disease diagnostic samples can be sent to the state pathology lab for analysis. There is usually a charge for this service.
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