Can you check to see if vine weevil grubs have eaten the roots? I believe that fuchsias are one of their favourite plants.
I agree with Kate - if they are in pots, tip an affected plant out and look for 'C' shaped Vine Weevil grubs. If in the ground, Vine Weevil isn't usually a problem (but still can be in some soils.) Here's a great web page for checking for diseases which affect fuchias:
Thanks for reply No vine weevil, Plants are treated twice a year and I don't think they give you the silver leaves, but have checket no sign. Thanks for your help Trevor
Are they in full sunshine? That might cause them to burn up with the temperatures we've had recently.
Some are but it does'nt seem to matter where they are, I have been growing fuchsias for a number of years and have over 500 at last count some 180 differant cultivars just feel helpless to see them in this state.