By Bernard
Cambridgeshire,
United Kingdom 
My young Acer pseudoplatanus 'Brilliantissimum' has been attacked by a problem I haven't seen before, but looks serious. The brown spots you can see on the leaf are not insects but little wart-like growths that are raised above the surface. You haven't failed me yet and I'm hopinh soeone will identify the problem and suggest a cure. Assuming there is one. Fingers crossed!
6 May, 2011
Answers
Thanks, Bamboo, I'm grateful for your help.
9 May, 2011
Acer gall mites - no treatment available, but they don't kill the plant, just look unsightly. You can remove leaves which are badly affected.
6 May, 2011