what is wrong with my morning glory leaves?

Hello,

My morning glories have a discoloration on the leaves as seen in the attached photos. The discoloration starts as the yellow-light green patches seen in the first picture and then look worse over time, eventually including some brown. Eventually the leaf turns yellow and dies.

The larger blueish white marks on the leaves are residual fungicide that I have started spraying. Does anyone know what the problem is here. I don't like spraying without knowing what I am trying to get rid of, but I also don't like losing entire plants while I am trying to figure things out.

I have checked for mites and don't see anything. Today I tried the bonaide copper fungicide spray because it looks like the issue is getting worse.

Thanks for the advice,

LMHmedchem