Black Spot On Container Roses.
Black spot on container roses the best course of treatment is to remove the infected leaves plus any fallen leaves around the base.You can spray with a fungicide available from a garden centre.Then in the winter prune the rose back remove all the leaves including the fallen ones and spay the plant with jeyes fluid a weak mix with water then finally add a mulch around the base of the plant such as fresh compost or bark this helps stop the black spot spores getting splashed back onto the new foliage from the soil in the container.