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Tomato brown/black leaf blotches

Hello
I’m starting out with tomatoes and have a question about marks on some of the leaves. Brown/black blotches, or brown veins and leaf undersides. I’m not sure if this is normal, some sort of water/nutrient deficiency or blight. Could anyone advise please? Sorry if this has been asked before.

plants are in their second pots and in the greenhouse with other tomatoes and chillies.

thank you. 

Posts

  • Pete.8Pete.8 Posts: 11,287
    They're fine.
    Sometimes purpling occurs because it's been a bit chilly for them - they don't like temps below 12c overnight for more than a few hours - but they'll recover.If you can keep them inside if its going to be a chilly night, but keep them outside during the day somewhere sunny.

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • pinutpinut Posts: 190
    The green colouring is due to Chlorophyll and is what enables the plant to grow.

    The purple/black-ish colouring is normal.

    It is a sort of sunscreen produced by the plant itself to halt growth when conditions are not favourable for it to burst into life.

    It happens when it is cold, when there is a draft in an otherwise warm room and/or when the sun light is too harsh.




  • pinutpinut Posts: 190
    I forgot to mention that the black colouring can also be caused by the movement of chlorophyll.

    Try this experiment: cover half a leaf with something opaque like a piece of paper or tape so that sun light can not penetrate. After a few days, remove the covering and note what happens.



  • Thank you so much for your help! I thought I was going to loose the lot before they had really got going. 
  • Pete.8Pete.8 Posts: 11,287
    They're looking good, nice sturdy little plants.
    As the weather warms they'll grow quickly

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
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