Sorry about your ‘taters.
By the time I saw the blight and researched it, it had spread to all my plants [10]. Some info said to pull out and destroy all the infected plants .... that would have been all my plants and I dreaded the thought! So I pruned all the offending branches [nothing to lose] rushed to the garden shop and got a chemical which I applied. Sadly it rained heavily 2 hours after the application.
I think I’m going to wait until tomorrow and re-apply.
Interesting that it spread the moment our temperature in the NE finally hit the 90s ... it’s been cool AND wet here all summer. I learned I should have been spraying the plants since the start. C’est la vie.
Are you losing all your potatoes?