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10 messages
18/04/2012 at 19:56

Hi ,can anyone tell me what is causing the black sootlike stuff on my rhododendrons,azaleas and pieris please and what can I do about it,they look a right mess ,never seen it on them before

18/04/2012 at 20:58

I wonder if this is sooty mould, although I've never seen it on my rhodo, azalea or pieris before, but have had it on my camellia.

Sooty mould develops on the surface of leaves when sap, or honeydew, drips down onto the surface from sap-sucking insects above. Scale insect is the usual culprit. 

Sheddy, take a look at the underside of the leaves above the sooty ones and see if you can find scale insects feeding. If you have then you'll need to try and get rid of these pests in some way (not easy), but if not we'll have to think again. Let us know what you find.

18/04/2012 at 21:51

It can also be caused by honeydew dripping from overhanging trees. If this is the case, all you can really do is wait for fresh leaves on the bushes. Although it's ugly, it won't do your plants permanent harm.

19/04/2012 at 15:44

Oh yes, and you can wash it off – although not sure you'll be able to use a hose pipe for teh job! I can't in my area. If the rain has softened the black coating try sponging it off, or fill a pressure washer with water and try getting spraying it away.

On my camellia I just went over teh bush with a bucket of water and a sponge, and this did the trick.

12/05/2013 at 15:53

I have the same problem with my pieris and it is so bad that the 'black soot' was all over the plant pot and stems.  I was told to spray the plant with water and bicarbonate of soda.  It has has one blast so far and the black is starting to wash away? watch this space

04/05/2014 at 22:05

Watching this space michizzle - any follow-up?

I have the same problem right now with a Pieris and Rhodadendrum side by side, both are covered in this black soot, especially on the older, longer leaves.  Those of the Rhody are drooping badly and turning yellow, just when the bush is attempting to be in full flower. 

An adjacent climbing rose tree also seems to have died suddenly, after giving a great display last year, and I'm wondering if it could be a honey fungus problem.



05/05/2014 at 12:03

I have the same problem on my azalea and pieris this year. Never had it before, and was wondering what to do. I will try your remedies. I have loads of buds but it looks as if they are not going to open!

26/03/2015 at 14:45

This 'soot' is all over an old established jasmine which covers the house up to the roof in one area. so washing the leaves is out ! It's also, though not so badly, affecting my row of large (4'+) potted camellias. Help!



26/03/2015 at 16:45

Small, sucking insects such as scale, whiteflies and aphids secrete a sweet sticky substance called honeydew when they feed. Within a few days, honeydew becomes infested with sooty mold. The best way of controlling sooty mold is to control the insects that produce honeydew.

The only way to keep the mold from returning is to treat the cause of the problem.

"Clean all affected needles, leaves, stems and twigs with a spray made of one teaspoon of liquid dish detergent mixed with a gallon of water. This not only removes sooty black mould, but also helps to control the aphids and scale that can cause it. Spray on the undersides of leaves as well in order to target aphids where they live. Rinse affected shrubs with forceful blasts of water from a garden hose to not only clean off residual soap solution but physically knock off aphids and mealybugs."

25/04/2015 at 20:33

Thanks will try this as I have got nothing to loose.

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