looks like scorch marks on my potatoes but not

[Elle's Garden]

Hi All, I have done a search, but can't see an obvious answer. I have a crop of Anya pototoes growing in various places, but 4 bags growing in the small greenhouse. 1 plant started with brown patches on the leaves that looked like the leaves had got scorched in the sun, and then the next bag over, and the next, so I hooked up a layer of fleece thinking it was the sun. I was sure it wasn't blight. I went to put the buckets of potatoes back into the greenhouse tonight (the buckets come out, the bags stay in - it is just easier) and the last bag of potatoes is showing the same effect. We have had hardley any sun and the fleece is still up so I looked more closely, and actually the underside of the leaf has been eaten/stripped away whereever the brown patches are. The outside ones are fine, just the inside bags.

I can't find a mention of what this could be in my Carol Klien book - but I am sure one of you will know . How do I get rid of whatever it is?

[peter]

Blight?

If it is just the indoor ones and you've had tomatoes in there before I'd question how well the house was cleaned for this season.