Purchase spray materials from a garden supply store to prevent bug and disease problems. A spray is more effective for preventing damage than a dust material. One spray should be a insecticide and the other should be a fungicide.
Spray both the top and bottom surface of the leaves of your rose plant or bush with the insecticide spray and the fungicide spray. When possible, spray with the fungicide after it rains to prevent black spot disease.
Keep your roses dry by planting them where there is adequate air movement and early morning sun. This will help prevent certain diseases, such as black spot and mildew.
Prune dead, diseased or infested leaves from your roses whenever you notice them. This will help prevent the problem from spreading to the rest of the plant or bush.
Avoid pruning roses too much. Each shoot should have a minimum of two leaflets, which each contain five leaves. This pruning technique will help keep the roses healthy and strong.