Success in growing roses happens when prevention measures can be applied in the very beginning when the rose bed is installed. Afterwards, impeccable cleanliness around the beds, and faithful pruning are very important. A fungicidal oil spray applied regularly protects the stalks from airborne fungi, and the tracking of spores by visiting insects. Washing hands periodically helps prevent spreading unfriendly bacteria. Keep gloves laundered too.
The soil the roses are living in must be free of root balls or discarded plants, or anything else that doesn't break down easily. Never leave old shards of broken pottery in the rose bed. Organic compost added to the soil makes the plants healthier, and consequently more disease resistant. All cutting scraps, and discarded leaves must be removed from the soil surface as these can harbor fungal diseases. I often mix up mild batches of soapy water to clean plants and soil surfaces (use dish detergent only.)
Pruning spent blooms helps keep healthy roses. Always prune with sharp tools (don't use scissors), and never make a horizontal cut. The horizontal cuts show the bright pulp like a beacon to insects flying overhead. If any cane borers are present, cap off the pruning cuts by painting the ends with Elmer's glue to seal. Usually cane borers like to go into dead stalks that haven't been removed. They look like tiny brown bees, and live as parasites draining the vitality of the roses, but they rarely kill off their host.
When watering, avoid sprinkling water on the blossoms or leaves. Be careful not to splash soil up onto the undersides of the leaves. An underground watering system is best. Otherwise, lay the hose down and soak the roots.
Roses need plenty of ventilation, plenty of water and fertilization, and most require full sun. Growing roses using disease preventative methods is a lot of work, but the exquisite fragrance and beauty of the roses makes the task well worth the time.