Question
Hi, and thank You for Your time.
 3 yrs ago I planted 2 identical syringa shrubs. Both had powder mildew last summer that i didn't treat.  The first one flowers every year. The second flowered  only the first year. This year I found Scales on it and treating it now with Orto systemic insect killer. What can i do to make it bllom next year? What about  removing bark? If yes, where do i have to do it?

Answer
I dont think you should ever have to remove bark, the plant will do that on its own if it is normal.  As far as the powdery mildew, mix up the following mixture and spray every 7-10 days.  Take one table spoon baking soda and one table spoon light cooking oil and mix with one gallon of water.  This is called the Cornell Fungicide and has decent activity on powdery mildew.  It may have to be sprayed every 4-5 days for good control. The scale insects are best controlled by using Bayer Advanced Tree and Shrub Insecticide which is mixed with water and poured around the base of the plant.  It is taken up systemically and will kill the bugs within a week or so.  It also provides protection from reinfestation for up to a year.  I hope these suggestions help you.  Good Luck.