[Umbrian]

I have a horrible, sticky sooty deposit on the upper surfaces  of the leaves of 2 Oleanders  - the stickiness seems to be on surrounding plants although not the sooty deposit. Can anyone tell me what it is and how to combat it please?

[Caroline]

You may have an infestation of minute scale insects which are secreting honeydew, which in turn is attracting the sooty mould.  It is a problem I get on my citrus; the answer is to spray for the scale insects.  I use something called Conqueror Oil which is petroleum-based - three applications at 14-day intervals. Alternatively, what about oleander aphids (little orange things which look more like pollen than aphids)?  They could be attracting something which is producing the honey-dew, and therefore causing the mould.

Let us know how you get on - unfortunately the sooty mould takes a while to wash off under winter rains. 

[Trevor Australis]

Make sure you use a Winter oil to avoid scald and defoliation should the sun still produce hot days.

[Umbrian]

Many thanks Caroline and Trevor for your advice - I am thinking in fact that the Oleanders will have to go I never realised how messy that can be. They are two big ones that I inherited in my new town garden and do provide screening in the one area where we are overlooked. I reduced them by half last year to rejuvenate them and hoped to do the other half this year but have been disappointed by the continual dead leaf drop that seems to be non ending and makes the whole area where they are situated a continual mess.....since the garden is quite small I do not want any areas that spoil it - and make such a lot of work!

[Caroline]

Maybe they are shedding leaves because of whatever is causing the sooty mould? Just an idea - if they've got to go, they've got to go.