Garden Pests and Diseases: Flaky white stuff on hydrangea leaves, 0 by CatMint20906

CatMint20906 wrote:
My hydrangea leaves have a lot of white, flaky stuff on them. A few of the leaves have also turned whitish in spots. The white flaky stuff is on the ground under the bush, too. This is the same bush where I found the caterpillars a few days ago. It is a very large, mature hydrangea bush that I recently pruned back.

Does anyone know what might be causing these problems, and how I can fix them? thanks.