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Any ideas what these plants are suffering from??????

This pieris  began to drop its leaves last year when the black powdery substance started to cover the leaves. I nurtured it ( well I thought I'd nurtured it!) and tried wiping the black stuff off but was never able to completely remove it all. I thought everything would be ok this spring but as you can see it isn't .  Any ideas what it is and how I can treat it please? Thank you 
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Posts

  • AnniDAnniD Posts: 12,585
    My guess is sooty mould, but it is only a guess.
  • ObelixxObelixx Posts: 30,090
    Looks to me like sooty mould which usually grows on sugary secretions made by aphids or mealy bugs or the like.   The mould will stop your plants from photosynthesising energy and will weaken so you need to clean it off. 

    Lukewarm water, a damp sponge and patience are the best way as any chemicals or soaps may burn the leaves.   After that I would suggest a thorough weeding of the pot and a good drink laced with some liquid rose or tomato fertiliser and/or a feed for ericaceous plants.  Do not use hard tap water as pieris don't like the calcium.

    Then you need to deal with the source of the problem.  Have a read of this info and follow the links for more - https://www.rhs.org.uk/advice/profile?PID=770

    Vendée - 20kms from Atlantic coast.
    "The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
    Plato
  • Papi JoPapi Jo Posts: 4,254
    Could be pieris lacebug see https://www.rhs.org.uk/advice/profile?pid=663
  • tattiannatattianna Posts: 182
    Thank you all for your advice. You can't see from the photos but it's quite a big plant and most of the plant is affected. I'm happy to persevere and keep chipping away at wiping the leaves but my guess is it's gonna take quite a while. Realistically if I stick at it what are the chances of eradicating the mould completely? Thank you!
  • ObelixxObelixx Posts: 30,090
    Clean the leaves so the plant can function and while you're there see if you can spot the source of the stickiness.  If it's aphids, you can blast them off with a spray from your hosepipe or squish them with your fingers or leave them for the birds and ladybirds and hoverflies and lacewings to eat.

    If it's scale insect, you can wipe those off with a cloth dipped in methylated spirits.  Check out that link I gave you and se what else it can be and how to treat it. 
    Vendée - 20kms from Atlantic coast.
    "The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
    Plato
  • tattiannatattianna Posts: 182
    Will do all the above Thank you 
  • ObelixxObelixx Posts: 30,090
    Let us know how you get on and if you find the pest.
    Vendée - 20kms from Atlantic coast.
    "The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
    Plato
  • tattiannatattianna Posts: 182
    Could these be the little rascals that are causing the problem?
  • DovefromaboveDovefromabove Posts: 88,147
    edited March 2020
    They’re the culprits ... scale insects 😖 

    https://www.rhs.org.uk/advice/profile?pid=224

    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.





  • ObelixxObelixx Posts: 30,090
    Yes.  Scale insects.  Not a lot you can do except wipe them off with a cloth or cotton pad soaked in methylated spirits or alcohol.
    Vendée - 20kms from Atlantic coast.
    "The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
    Plato
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