Help needed troubleshooting Japanese barberry

I am located in Connersville, Indiana. We have had a nice hot wet summer and I am having trouble determining if the cause of dying Japanese barberry. Is it too much or too little water. Maybe something else? They were planted this spring and have looked great up until a couple of weeks ago. The soil seems to drain adequately and there is landscape rock, not mulch. I have posted photos for reference.

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