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Black mould on Oleander

Hello, I hope someone can help me. My Oleanders are suffering from black mould on the stems. It’s hard to the touch an disintegrates easily. Please see pictures. Do anyone know what it is and how to cure it?
many thanks 

Posts

  • amancalledgeorgeamancalledgeorge South LondonPosts: 2,018
    That looks like scale insects to me... https://www.rhs.org.uk/advice/profile?pid=224
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  • NollieNollie Girona, Catalunya, Northen Spain.Posts: 4,714
    Yes I would say scale insect too, looks not dissimilar to olive scale. 
  • PeggyTXPeggyTX Posts: 532
    edited July 2019
    I don't recognize the disorder, though it looks like too much water if the leaves are yellowing, but know that oleanders that are heavily pruned rejuvenate with very healthy new growth and very rapidly.  I had 50 of them around my back garden on the TX Gulf Coast years ago.  They often froze off in winter.  As my neighbor was president of the local oleander society, she said "Peggy, just cut all branches off right down to 10" and watch how fast they come back."  Fearful or doing that, I took her advice the next freeze and was so pleased to see what happened.  By spring they were 3' bushes with many more branches and double the bloom production as well.  By full season they were nearly 4-5' and by end of fall, they were back to their normal 10' height. So I adopted that approach any year we had hard freezes and they took a death spiral.   They never failed to return healthy and more vigorous than the year before.  Soa fter you treat for whatever disorder you think might be at issues, if it doesn't spring back, you might consider a heavy pruning nearly to the base.

    I had a love-hate relationship with those 50 oleanders.  Hated all the branch lopping I had to do to to keep droppings out of the swimming pool and at a reasonable height, but the pale pink strain similar to yours (sorry I never knew the cultivar name, as a previous owner had planted them), well, they had the loveliest baby talcum scent that permeated the garden for months and months, until first freeze.  Yes, even Galveston Island gets the occasional freeze.   I was never around any other variety (and Galveston Island had many) that had a scent that was pleasant like those had. 
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  • NollieNollie Girona, Catalunya, Northen Spain.Posts: 4,714
    I think it is Black Scale, there is a telltale H marking on the back of the insects now I have zoomed in. I would wear a pair of thin gloves and rub off all the insects into a receptacle and dispose of. Then spray the plant with mild soapy water to clean up and hopefully suffocate any you miss, then keep the plant out of the sun for a few days to avoid sun scorch from the soapy water. Rinse, dry and pit back outside.

    You can prune off those damaged, blackened tips wearing heavier duty gloves, but take care to dispose of the prunings in the rubbish bin as the sap is a serious irritant, don’t add to a compost heap.

    Also, don’t be tempted to use any branches for barbecue skewers. Seriously, there are several reported hospital admissions a year here, of young folk camping out by rivers and using hacked off branches of handy oleander as kebab skewers, then poisoning themselves!


  • floraliesfloralies Haute-Garonne SW FrancePosts: 1,279
    They are scale insects. You can dab them with methylated spirit which penetrates the their hard scale. This was very successful when I had it on mine.
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