Help! Potato leaves going yellow - whats up?

[Sternchicken]

Can anyone help diagnose what's going on with my spuds?

Over the last two days a high proportion have started to show yellowing in the leaves. Facts as follows:

- planted about a month ago, through permeable membraine. Five varieties of scottish seed potatotes, including red duke of york, charlotte, picasso and kestrel. All are showing symptoms
- yellowing is taking place in new leaves only. The worst are drying out and going crispy, most are as yet just going yellow. Some plants show only on some of the stems, others on most
- this has been noticed only in the last couple of days - fast onset. Till then all plants seemed very healthy
- so smells, rot, dust etc. No sign of any insects
- no sign of any problems with stems, down to an inch or so below ground
- being grown on reasonably well drained but moist Wealden clay in Sussex
- ground was part of a meadow till last autumn. Was sprayed with roundup, then kept covered with membrain all over the winter

Anyone know whats up, if its serious, or if I can do anything about it?

[Lez]

very tricky. they are under membrane so have they enough moisture?. new ground is the residue from the round up?. I don't think the round up is to blame unless you were very quick planting. the dryness of the leaves tends to make me think lack off water. did you plant straight into virgin ground or did you add manure? if you added manure I wonder where it came from as there has been some discussion over the last few months about comtaminated manure after gras had been treated with a weedkiller. they do say that the foliage deforms aswell. is anything else showing signs?. all points to a disease how ever black leg is out as you the stems are sound. I will give it more thought and meanwhile some one may have a better answer. I will keep watching good luck.

[DavidT]

Have you had any frosts in the past few days? As that`s what it sounds like.

[Lez]

yes it could be frost. mine got nipped a few days ago but they usually go black rather than yellow. we don't where they garden as it would have to be a good sharp one to take down all plant I would of thought.

[Saturna]

It's unlikely to be related to the Round-up as thats a non residual weedkiller, more likely to be frost damage or possible magnesium deficiency