There are no fungicides that you spray on out there that do not need to be reapplied after a rain. There are also no pesticides that you spray or dust that will not need to be reapplied after a rain.
For the beetles simply knocking them into a bucket of soapy water works. Once the rain stops for a day or two spray with a 50/50 mixture of fat free milk and water for the Black Spot every 5 days until its gone and then every 7 to 10 days to keep it away.

Only sulpher has any decent activity against Southern BS. And, was only 40% effective in my trial. It washes off. The best choice is to shovelprune your BS magnets and plant roses that aren't as succeptible. There is a whole world of no spray choices available to those in the South, but they won't include 99.9% of hybrid teas and other modern roses. Or, grow the moderns and do some research into modern fungicides, which are far more effective, less toxic, have a longer spray interval, and do not kill insects or other garden friends.

I am in NC and have been dealing with the rain and B/S as well. I have found a lot of success with the diluted apple cider mixture that I found here on this forum. I started spraying it on my B/S affected roses every 3-4 days. It has totally wiped out my Black Spot Problem! I also concur in finding varities that are disease resistant in your area. I am loving my Traviata right now. She's a looker and hasn't developed a single black spot in sight among all this rain.
My 2 cents
Shelley

The Safer product is a sulfur fungicide, and they do wash off too easily. Combining sulfur with liquid seaweed/kelp will help. The seaweed forms a film that doesn't wash off immediately, plus the roses like it. I have been experimenting with sulfur and Wilt-Pruf, which seems to have better adhesion. I'll report on that in a week or so.

Shellemarie, Traviata has been a very easy rose for me as well.