Tomato leaf discolouration - advice appreciated
 

Hello All,

I have planted some Tiny Tom tomatoes in my new greenhouse :) and have noticed some leaf discolouration on the topmost leaves. The larger, older leaves seem unaffected. I have tracked back through previous threads and the closest I have found is a thread back in 2007 in which there didn't appear to be an obvious cause.

Rather than try and explain, I have posted a couple of pictures:

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There is no damage on the back of the leaf, so I have delayed taking any action against fungal or bacterial disease. I thought it might be sun scorch, but we have barely any sun since the toms went in, and the three other varieties of tomatoes (Shirley, Gardners Delight and Moneymaker) appear to be completely unaffected.

The plants were sourced from a local producer with a good reputation and appeared fine when I got them, so any problems appear to be of my making.

Can anyone help with any suggestions.
Many thanks

Flayme