Good Morning Joel, 

Thank you for contacting the U of M Extension Service. 

I am not familiar with a magnolia shrub. Do you know the hybrid or the grower? Based on your photo, this plant appears more like an azalea or rhododendron.  If you would like an accurate plant identification, send another photo of the leaves/branches closer up. 

Have you inspected the stems and the back of the leaves for pests or disease? Many magnolias are experiencing scale insects infecting the plants. Here is a link about scale insects: https://extension.umn.edu/yard-and-garden-insects/scale-insects

From viewing your photo, the landscape rock should not be up against the stem of the plant. I would suggest wood chip mulch under the shrub, a few inches away from the stem to outside the drip line of the shrub. This mulch would keep the soil cool (the rocks are heating up the soil and the plant in the sun) and moist and protect the roots. I am assuming you DO NOT have landscape fabric under the rocks that might be impeding the water absorption. The heat reflecting off the rock in the sun could have a negative affect on your shrub. 

If it is an azalea, it would require a lower pH soil content to thrive. It appears to be sending up healthy shoots. 

Good Luck!

Good Evening, 

Here is a link that discusses possible problems: https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/azalea/leaveswilted.html

Here is a link to the soil testing lab: https://soiltest.cfans.umn.edu/testing-services/lawn-

garden

The soil pH for a rhododendron to survive is between 4.5 to 6.0. You might ensure your plant was planted with fresh soil and compost. If the soil pH is too high, you should adjust the soil pH so it will thrive. They thrive is acidic soil. 

My guess is the pH is too high and it is struggling. 

Good Luck!

Forgot to include another link about the soil pH: https://www.rhododendron.org/v46n2p77.htm#:~:text=The%20soil%20for%20rhododendrons%20and,graduated%20from%200%20to%2014.