The shrubs look like cherry laurels. The white coating on the branches is white prunicola scale, a sucking insect and this is a heavy infestation. This insect causes leaf yellowing, drop, and branch dieback. We recommend removing the heavily infested shrubs 1 and 2.
Shrub 3 - You can brush off the scale with a soft brush. When the plant is dormant, (look at other deciduous plants and see when they drop their foliage) is the time to spray with a dormant horticultural oil. Follow all label directions.
This may help to reduce the population, however, you will have to monitor the plants next spring. If you see crawlers in June, you can spray with a summer rate of horticultural oil. You may decide to remove the shrub and plant another type of plant
if you cannot get control.
This scale is a preferred host of Prunus, flowering cherry, lilac, and privet.
Take a look at our blog on cherry laurel and how to grow this plant in your landscape. https://marylandgrows.umd.edu/?s=cherry+laurel
Yes, it would be best to dig out the root system as well.