Hello, 

This is white prunicola scale! At this time of the season, you could try spraying the scale off of the branches with a hose. When the tree is dormant late fall or early spring you could use a dormant oil to smother the scale. 

This resource from University of Maryland has more details: 

https://extension.umd.edu/resource/white-prunicola-scale/

It refers to Growing Degree Day model for timing of control.  You can find Growing Degree Days for around Michigan with our Enviroweather site: 

https://enviroweather.msu.edu/weathermodels/weathersummary