It looks like this symptom is due to egg-laying damage from the periodical cicadas. In the right-side circled portion of your first photo, we see small incisions that are characteristic of their "nests." They produce a line of small vertical dashes/cuts into woody plant stems where they insert their eggs. This eventually leads to some stem dieback (leaf curling because the water flow is disrupted). Inspect the other stems to see if these small incisions are present. All you can do for this is prune out the damaged portions.

In addition, we see some minor leaf spots on the foliage. Hydrangeas can be susceptible to several leaf spots -- more common in wet seasons or in garden beds with regular irrigation that dampens the foliage. Hydrangeas and different cultivars vary in their susceptibility.

Avoid overhead watering if you have a sprinkler system and remove heavily spotted foliage during the growing season. Rake up fallen foliage at the end of the season. These sanitation practices will help to manage fungal diseases from year to year.  In general, no fungicides are recommended as you may have to spray all season.

Christa

Thank you Christa.