I figured out that my problem was definitely not powdery mildew. I have a few rose bushes that have powdery mildew and like the name says, it IS "powdery." A very bright white too. It is literally like the leaves were dumped cooking flour on. It is powdery and if you hit the leaves or wipe them with your finger some of the powder will come off. On my plants, I think the small white dots are from the spidermites, but there is also light white-ish patches on some leaves but have been watching these carefully and these have not spread greatly in any one particular leaf. I think these white patches are just mineral deposits possibly from the splinkler or just from sitting in the sun, but I have sure that I do not have this powdery mildew as I had feared. How are your plants now? And do they match the description of the powdery mildew on my rose bushes?
Best of luck,
Grow Info