Help, I have lived in my house for over 8 yrs and we have 2 very large Oak Leaf Hydrangeas (6'X6' or maybe bigger) in the front yard. The plants are right next to each other. One of the hydrangeas looks like it is dying, the leaves are wilting, turning brown and then falling off. I have taken a knife and scrapped some of the bark off and I see green so that is a good sign, I scrape bark further out on the limbs and they are brown and dry. We have had a pretty hot summer this yr here in St. Louis but my question is why would one plant have issues the other would not? Another thing I noticed was small ants around the base of the hydrangea so I have put some Tero baits for that issue. Would appreciate any suggestions, ideas or just plain knowledge on whether this plant is going dormant or has a more serious issue. Thanks!