A. If the brown spots are dead, shake off the dead parts. I'm sure you have been trimming the new growth every year off your cedars or they would be difficult to maintain uniformly unless you like them with the natural bushy look. If it is the later, never trim back more than one-half of the NEW GROWTH. As a rule, when you trim any evergreen, including cedars, back to the old growth with no needles or foliage, it does not produce new growth.