we have to see what you are talking about ...

i was not aware that PM is an issue... especially on DEAD WOOD ...

dead wood is dead ... who cares if it has mildew on it ...

ken

Sections of pale foliage appearing during summer can be mites, which definitely get on these here. Otherwise cultivar is more prone to root rot than usual, resulting in quantities of questions on the internet about hedges of it developing dead, brown sections. But it doesn't sound like that is what you are asking about.

If you have pieces you think aren't right you can cut and transport samples of you might want to try your nearest USDA Cooperative Extension branch office - if you can get there during open hours. Or at least a good independent garden center.