By Sunshines
england,
United Kingdom 
hi please can anyone tell me what this black stuff is on my rotadendrum leaves many thanks
14 Nov, 2010
Answers
I agree, it looks like sooty mould from either aphid of scale insect. Treat the insect and the sooty mould loses its food source and will wash off.
15 Nov, 2010
looks like sooty mould. You probably have had greenfly on the shrub and they exude a sticky substance called honeydew. this then allows a mould to grow. There is commercil sprays availabe to cope with this.
14 Nov, 2010