is this blight?

Hi,
   spotted this the other day on my spuds. Only seems to be on the lower foilage but looks like its working its way up. The lower foliage has now died and dropped off. Have looked at various pics on net but im unsure and want another opinion. Photos are attached, its on my Anya and King Edwards.

Thanks
Liam

I don't think it's blight either it looks more like magnesium deficiency.  Give them a spray with some epsom salts.