This has been a particularly bad year for Magnolia Scale. Magnolia scales are soft scales. You can start treating this fall by spraying with horticultural oil. If you wish to try to remove some of the honeydew secreted by the scales now you can spray with insecticidal soap. Here is a link to our publication on how to treat Magnolia Scale. There are areas in the pub that have drop down expansion parts. Go to the Soft Scale on deciduous trees and click.  https://extension.umn.edu/yard-and-garden-insects/scale-insects-minnesota-trees-and-shrubs