Black spot is a fungal infection on the leaves. Cool, damp weather and poor air circulation encourage the fungal spores. Remove the lowest leaves as soon as they turn yellow, clean up the area below the plants, and apply a fresh mulch. A fungicide spray such as Funginex will help control black spot and other fungal infections on roses. There are also disease resistant roses such as the landscape roses (Flower Carpet, Easy Elegance, Knock Out roses) that are more resistant to all rose diseases. Keep growing, Marianne Binetti