All roses are prone to a number of diseases and/or pests.  This makes it necessary to start spraying them within a week of planting, and continue spraying until the end of the growing season.  Most sprays are on a 7-10 day reapplication schedule, although the label on the spray will tell you for certain.  A single spray blended for roses that controls all insects, mites, and diseases problems simplifies the matter.    Another simpler alternative to spraying are granular products that once applied around the base of the rose and watered in, they soak in through the roots of the rose and protect for weeks or even months.