On 20 Feb, 09:52, "Bob Hobden" wrote:
"Richard Burge" wrote
If i didn't know better i'd say sooty mould from aphid "droppings" but
it's thr wrong time of year. These plants (4 to 5 feet) have been outside
all year and have sooty black deposits on the leaves. These deposits rub
off with a finger or thumb.
These Ilex Aquifolium are variagated, in pots and we're stumped...
any ideas for what it is and a control?

Scale Insect.

Sounds like it indeed. Richard, you should have seen the scale insects
last year and now the mould is living on the honeydew they extracts.
Check this for confirmation. I have a similar problem with an acer.
Every year without fail, if I don't get rid of the scale insects,
everything below that tree is later covered of sooty mould.

http://www.dgsgardening.btinternet.co.uk/scale.htm