Speaking of blight and since tomatoes are relatives to potatoes it seems like wood vinegar as a very diluted foliage spray (in the second link) would work.
This might be very obvious for you dow veterans but it was new to me although I have read something about it in another thread here on dow but I can’t recall which one, was it you Kristijan that wrote about that perhaps?
I thought I’d post it anyway since that season is upon us or soon to come depending on where you live.