hydrangea leaves turned silvery

We ve had a long wet and cold season and can count on one hand the fine days we ve had since Christmas.My guess with no pic would be powdery mildew.Whatever the cause would prune hard back to buds not leaf so that all leaf growth removed in the hope that new leaves not affected as they develop.

If it is powdery mildew you can spray with a baking soda suspension... just dissolve a half tsp of baking soda in a quart of water and spritz it on...get as good coverage as you can, if it is powdery mildew it should succumb.