Acer Pseudoplantanus Brilliant issimum
 

My beautiful little tree seems to have dried brown shrivelled leaves does anyone know why?

Also there is a white deposit on the underside of many of the leaves could this be a fungus?

Any advice would be gratefully received.

Pat Rolt

You say 'little tree'?
Does this mean it's newly planted or is it in a pot?

Are the shrivelled leaves of the new groth at the top and near the ends of the stems or are all of the leaves shrivelling up?

The white fungal deposites may be powdery mildew, which is usually a symptom of a plant being rather dry, shady and with bad air circulation, also underfed plants are liable to it.
It can be easily cured by changing the growing conditions.