We Have Annabelle Hydrangeas And The Leaves Went Black In The Summer, It’s Now Early Fall And They Didn’t Get Better.

Question

Full morning sun and afternoon shade.

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Answer 1

This looks to be Cercospora infection. Current action consists of treatment and prevention rather than a, true, cure. This will be, mostly, keeping all infected growth discarded of (not in your compost) and kept away from the ground and soil. Treating with fungicides can help, but this must be done, consistently, throughout the year.

Here is an article that will help:

https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/spots-on-hydrangea-leaves.htm