ljmmus,
Only water once a week, and when you do, water deeply.
Leave a real small sprinkler on it, you can buy a round one cheap, and really soak it for awhile, really early in the morning, really early, or after dinner.
I think you are watering it too much.
2-3 times a week seems excessive, and are there stones in the pic?
Where are these stones?
You have a good 2-3 inches of pine mulch around the base of this tree, right?
You aren't using stones as mulch, are you?
If you are, get them away from the tree, and put down some pine bark mulch for your magnolia.
A good perimeter around it, the roots are shallow on this tree, it needs mulch, not stones.
The stones will fry your tree. Seriously.

Butterfly4u,

Thank you very much for your suggestions. I will water it as you suggested.

The stones are around the tree, about 1 foot from the tree base.The tree is located near the curb. There are stones before. I just dug a hole and filled the hole with garden soil. I did not put mulch. I will get the stone away and put mulch.