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White powdery residue on soil by courgette seedlings

Hi everyone, do you know what a white powdery residue on the surface of seed compost for my courgette seedlings might be? It's only on a couple of them and the seedlings are strong and in good health. Should I remove it or plant out with it in place? Thanks


  • GemmaJFGemmaJF Posts: 2,286
    I'ts powdery mildew. I spray with 100% success with a dilute hydrogen peroxide solution. Doesn't harm the plants and breaks down to pure water.
  • Pete.8Pete.8 Billericay, EssexPosts: 9,867
    edited April 2020
    If the white stuff is only on the surface of the compost it's likely some sort of fungus which will die almost as soon as you plant them out, so nothing to worry about.

    If the white 'powdery residue' is on the leaves of your plants then it may well be mildew.

    A photo would help us be more specific
    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • GemmaJFGemmaJF Posts: 2,286
    Just checked up on this, Pete.8 is right it is a form of mould, powdery mildew only survives on a host plant, not on compost. I treat in when I see it in the propagator with the peroxide as it tends to spread rapidly in the humid conditions. So the treatment still works, though misidentified what it actually is.
  • Thanks all. I've planted it out today so hopefully the mould will go now it's breathing outside and in the sun
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