Probably powdery mildew, from my superficial glance at it. It's a common
problem with roses, particularly in the spring and fall when night
temperatures are low and humidity is fairly high. Some varieties are more
susceptible than others. It rarely kills the rose bush. Sometimes they will
lose the affected leaves and grow others. In any case, with the arrival of
summer and warmer nights, the problem should disappear.
"Renee" wrote in message
...
I posted a photo of the problem I'm having with some of my rose bushes at
http://photofan.multiply.com/photos/photo/13/1.jpg

It's going to be a couple of days before I can get a sample over to my
local nursery so I thought I'd ask here first.

Does anyone know what the problem might be? Do I need to treat it with
something?

The other day I noticed some tiny white specs on some of the leaves and
buds. I had a rose insecticide spray handy that I'd had for quite some
time, so I shook it up and used it to spray the bushes. Could old
insecticide have caused this? Could spraying in too hot Florida weather
have caused this?

I spray regularly with fungicide and it doesn't look like black spot.

Thanks in advance for your help

Renee