Help - My Acer Crimson Sentry is poorly

I have four Acer Crimson Sentry - three of which are doing v.well. However, one has developed a white 'bloom' on its leaves. What is this, how can I treat it, and I should I be worried about the other 3 catching it?
Thanks for any advice you can offer.

[ 08. August 2005, 07:14 PM: Message edited by: Sue Gill ]

 

Mmmm sounds a little like mildew - very common on some plants at this time of year - especially with the dearth of rain. If it is, try a fungicide spray, and water well - or rather the other way round .