poorly japenease acer

Probably sunburn or wind burn. They don't like it if there is water on leaves and then strong sun.

thanks chris, so will it go back to normal if i keep it out of wind/sun?

I have several in pots and keep them in a sheltered place. Recently, I put one in my son's garden and he left it out in the open and its just like yours. I think heavy rain followed by sun caused it. It may not recover till next year although some of them are still growing a few new leaves.
They do like some shelter. Where have you got it growing?

I've got it in a pot and have been moving around during the summer so i guess i'll find it a nice sheltered spot and keep it there. thanx for you reply, i'm glad it will come back.