Botryosphaeria in Hydrangeas
I previously asked about wilting branches and sent pictures. You said it looked like Botryosphaeria and to prune the affected branches. Is there any other treatment you would suggest for the affected plants as well as those plants not yet affected?
The best recommendation is to prune all dying branches out in dry weather and all discolored wood should be removed. These plants grow best in morning sun and afternoon shade. Make sure mulch is not thicker than several inches and keep away from the base of the stems. Keep well watered during dry periods.