A rose problem is almost always a reflection of the plant's environment. Bad drainage, too little water, poor soil preparation, insects, disease - all are environmental conditions that can either be remedied or prevented from the start.
This chart, prepared by Jackson & Perkins, will help you diagnose and treat problems. Plant problems can be caused by either living organisms (insect, fungal or bacterial pests) or non-living cultural conditions. If the damage is uniform it is usually a non-living cause, while living pathogens cause non- uniform damage.
How to Check and Treat Rose Problems PDF