Take up all the affected plants and their neighbours and check the potatoes carefully before storing. Destroy the foliage - do not compost it. Look out for it if you're growing tomatoes too. They're teh same family and suffer the same blight.
Vendée - 20kms from Atlantic coast.
"The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
Cut the foliage off and bin it, then wait a week and then on a dry day dig the potatoes out, the reason to cut and then wait is so that the skin on the potatoes sets and then the blight spores that are present on the soil do not invade the potatoes as you harvest them. If it does then they will rot in storage.
I would personally only cut the rows that are affected and leave the others for now. but keep a close eye on them, unless they are a resistant variety they will probably only be a week or so behind.
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