Welcome to GoY Imccollum, to the best of my knowledge there is no treatment for blight. If it is in he early stages you can just remove the affected leaves and watch like a hawk but if it is already affecting the fruits the only solution is to bin the plants - do not compost or put in your recycling bin. With the constant rain and humidity there will be a lot of blight this year so watch your potatoes too.

For Botrytis mould increase ventilation and remove affected leaves. For blight (Phytopthera) you should destroy the plants.