It isn't always easy to tell what's the problem more so in the early stages coupled with possible dual problems. Hope you tatties make it through
Here's a couple of mine with I think Early Blight
I did read somewhere that if you take a leaf you suspect to have Late Blight (before it is obvious or weather is very dry to mask early symptoms) and put it on damp kitchen paper inside a bag and leave it for 24hrs, white fungal growth should be apparent on the underside of the leaf if Late Blight.
