Rose magazine suggests making a solution of 1 teaspoon baking soda in a quart of water along with a few drops of liquid soap and spraying it on the roses, but black spot is not something to be messed around with, and the time-tested treatment is a copper fungicide.
I am trying a spray of 1 part milk to 2 parts water and spray weekly. Also pick up any leaves that fall off as they spread the fungus back to the rose bush. Hope this works as I have tried many things and haven't had much success.
Thank you Douglas and Stella! I was wondering how severe black spot was. I had tried one home remedy that didn't work. I guess I'll have to go purchase some copper fungicide.
I finally purchased the treatment from a local store and applied it every two weeks. My roses are doing beautifully now! Thank you!