Hello There,

I wonder if anyone can tell me please, what the powdery black substance is
that is covering my leaves on my Citrus Tree, Bay Tree and my Nectarine
plant is? It also looks like it may be spreading to my Grape Vine. All these
plants live in my green house in the North West of England. Ive looked for
answers through the web, but im not 100% sure.

Thanks in Advance

JAmie