Q.weigela with powdery substance
My weigela bush has white powdery substance on some of its branches. I am trimming my well-established weigela bushes after their spring bloom and I noticed this year that the backside of the bushes (next to my front porch) have a white powdery substance on some of the branches. What is it and what can I do to take care of it?
Your plant has Powdery Mildew. You can use Neem Oil to treat.
Here is a link with more information.