[lozenge]

everything was going nicely but over the week some of the plants have started looking sickly - leaves in the middle are yellow and curling and have some dark brown spots. some plants are fine and it seems to be quite random (i've planted 4 types; probably two of each are affected). i've been quite neglectful about watering this week, could it be that?

[Salmo]

Scroll down and look at the topic "Contaminated soil???"

Do your potatoes look like the photo?

[Ivor Backache]

Watering is not the problem. potatoes don't need it yet.  Assuming you have bought proper seed potatoes, and all types are affected, we need to look at the soil conditions.
Have you used any farm manure? Can you provide any photographs?

[paintedlady]

frost damage?  We've had some real temperature dips this past week - damaged foliage can look a lot like blight and much worse if it is particularly bad.

[lozenge]

i've used manure from the stables next to the allotment - used the same last year with no problems and i've also used it all over the rest of the allotment with no other sinister effects.

crosses fingers that it was the frost the other night....

[gobs]

I'd go with PL, most likely thing to happen without seeing this time of the year.

Watering potatoes, pah, where are you growing, in the Saharan desert sand ? That is a  horrible waste of water - and effort -, I don't water them ever at all.

[lozenge]

Will revert to no-watering strategy!

My mother in law also reckons frost. Also, I notice that the volunteer potatoes are doing just fine on the patch of fresh manure rotting down. Grr.

[gobs]

The manure keeps them warm.