How to care for a purple leaf ash tree?

Oh my gosh, I have no idea! Try your local Agriculture University extension agent. Google that - enter your County name & state withUniversity extension. Add in there Master Gardeners & you'll surely get a hit. Good luck.

http://hort.ufl.edu/database/documents/pdf/tree_fact_sheets/fraamec.pdf

https://gardenerdy.com/common-diseases-in-ash-trees-their-treatment

Hi Georgia, this could be caused by a mite brown clusters hanging from the trees that look like a cocklebur. These clusters are caused by an eriophyid mite, and the damage is commonly called the ash staminate flower gall. Galls can be caused by insects, mites, bacteria, fungi, nematodes and mechanical damage.

Or this could be a fungal problem, here is a link with information about that

https://www.ag.ndsu.edu/news/newsreleases/2010/may-17-2010/anthracnose-hitting-ash-trees-hard#:~:text=%E2%80%9CThe%20leaves%20are%20falling%20due,this%20year%20it's%20especially%20problematic.%E2%80%9D&text=Trees%20that%20lose%20this%20quantity,the%20most%20susceptible%20to%20decline.