Cheshire, United Kingdom

I have an Acer Brilliantisima which I planted 3 years ago. Every summer, after a good start with the leaves opening, it is attacked by pests which cause brown patches on the leaves, which then curl up. I water it regularly in dry weather and this year I've sprayed it weekly with a good quality insect spray, but I can't keep up with the pests. I've been taking off the affected leaves, but the insects keep coming back for more. I'm not sure, but think they might be red spider mites. Other plants and trees nearby not affected. A new Robinia and 2 saplings (I think they're Whitebeams) have had leaf curl, but seem to be responding to treatment.

• 25 Jul, 2010