welcome to garden web..you came to the right place..the people here will get you on the right track in no time.
In general, you can pull off the lowest infected leaves on the bush, but if you pull too many off, or the leaves on the top of the bush, the bush will suffer. Don't prune the branches. I am assuming that the bush isn't heavily infected right now, or it would be dropping leaves on it's own...you don't say what zone you're in, (people here usually put their zone number next to their name)..this makes it easier for other gardeners in your zone to help you..
if you are a southern gardener where blackspot is a bigger problem, you will probably need to spray, and figure out if you want to go organic or chemical.
if you are in a less harsh blackspot area, like I am, I just live with a little blackspot, it drives some people to distraction..some people can live with a little....
you need to post again and tell us your zone and what percentage of your leaves are infected, then people can help you more. Donna

There is also the option of selecting roses that are more resistant to blackspot if you are not interested in providing chemical support. You may want to check out the antique rose site as well.

Welcome.

Robert

If you live in the Eastern half of the country, picking leaves won't be enough to let you grow typical garden-center roses decently. Either get rid of them or spray fungicide. I recommend Bayer Rose and Flower Disease Control (containing only tebuconazole, no combo products please) applied with a pump-up tank sprayer. It is available at most Lowe's. If you use this product, don't pick off lightly-spotted leaves, as it will cure them.

Thanks for the help. I tried to click on the Zone link but it seems to be broken. I live in northern VA and we have had a lot of rain this spring. The bushes are heavily infested and one of the two is dropping leaves. I was told at the garden center to use Rose Pride (I also have holes in the leaves possibly from Japanese Beatles as I definitely have grubs in the yard). I sprayed the Rose Pride twice one week apart but haven't noticed an improvement.

I have read that 1 tsp of baking soda with a quart of water would help prevent the fungus, is this true?

The Rose Pride fungicide is barely satisfactory-- under bad conditions, it won't give full control as Bayer Disease Control and Banner will. It is maybe slightly more effective than the organic remedies and won't burn foliage as those can do.

A mixture of baking soda and oil (Cornell Mixture) is somewhat effective. See the FAQ of the Organic Rose Forum for this and for sulfur, which I prefer. However, if you want to stop the blackspot, get Bayer Disease Control. The organic remedies are fairly effective only if you start at leaf-out and spray thoroughly every week. Even so, you would have to be somewhat selective about varieties, as you live in one of the worst climates for blackspot.