Of course I'm no expert but based on my own experience I wouldn't do anything. Last summer of '08 the leaves on many of my roses turned blackish and fell off leaving the stems bare except for the top 1/3. I was concerned since two of the roses were prone to blackspot ie Persian Yellow.
But everything came out fine this year. I think it may have been due to the extremely wet & cool summer we had. PS I live in Northern Ontario.

This just happened to my Persian as well - it's brand new and i didn't realize it was prone to black spot. Oh well - live and learn!

We did have a lot of rain this year, but last year we had quite a bid of rain as well, and no problems with the roses. I guess since it's so late in the season, I'll just keep cleaning up the affected leaves, and see what next year brings. Thanks for your comments.

Joan

I have had good luck using a mix of about a quart of water with 1 tablespoon of apple cider vinigar, spray plants as needed. There are lot's of good tips on the GW organic rose forum that I have used over the years.