[Ice]

My chard is not at all healthy.  I've looked in Doc Hessayon but can't find anything to exactly match.  Any ideas please?

[noshed]

It could be a virus - or maybe magnesium deficiency - see if Epsom salts help.

[Ice]

Magnesium deficiency is one of my mantras for other peoples problems.   Could well be, but I would have expected it to be a little more yellow.

[viettaclark]

Looks like a sort of rust? Does it affect the taste? I would cut the plant right back. It will soon grow and you can see if the new growth is affected.
This weather is to blame for a lot of problems!!!

[Ice]

Don't fancy eating it looking like that.  Might do as you say and cut right back and see what grows.  My perpetual spinach which are growing in the same bed are fine.

[JayG]

What's the new growth like?

The affected leaf does look like an old one and there do seem to be the sort of lesions which fungal attacks can produce. Maybe it's just had the worst of the wet weather and with any luck if you take them off the new ones will be more lucky. 

[sunshineband]

Some of ours went like this last year and I just took those leaves off and the rest were fine.

I think it is perhaps old age 

[Ice]

I think it is perhaps old age 

Don't write yourself off just yet.

I'm going to cut them off and see how they grow back.  This has been a horrible season to predict.  No slug damage at all anywhere, but a plague of whitefly, greenfly and blackfly on a scale of which I havn't seen before.