Question
I have this white powdery substance that is accumulating on the branches of ornamental cherry trees as well as on fruit bearing peach trees. The result is the loss of foliage and subsequently the branches have died. Closer examination of the leaves indicates that little to no accumulation of the white powder on the leaves. No spots are identified on the leaves. How am I able to rid my trees of this white substance.

Answer
Marios:
Can you attach a closeup photo of a few of this substance on a branch? It may be a type of insect like mealy bugs or aphids.  Review your image on your computer first- to be sure it is in focus before sending.
OR, you can snip off an affected twig and carry it to your local garden center/nursery and ask them if they can ID this substance.

Thanks
Steve