Rose Disease What is it?

Could you look at the picture and help me out?  I know I have whitefly but what is the white covering which looks a bit like paint?  Thanks.

http://s1090.photobucket.com/albums/i379/bobloes/?action=view&current=DSCF2664.jpg

I dont think it is a disease- just a bad insect infestation possibly mealy bug-just wipe it off

Thanks Geoff.  Not sure about the mealy bug but it wipes off easy enough.  Maybe I shall try that first in future rather than asking a dumb question.  Cheers.

To me this looks like a case of mildew, caused by damp weather.