The battle with insects that plan to suck the energy out of your roses continues from spring before the first buds open, until later on in the summer, when the flowers are in full bloom. Insecticide is the solution for summer pests like thrips and spider mites but Japanese beetles must be handpicked.
A common rose disease is powdery mildew when the leaves, buds, and stems are covered in a white powdery coat. It is a fungus that develops in warm humid weather but can be reduced by proper sanitation - removing all dead or infected branches and keeping the rose aerated, and by fungicide application.
Another common rose disease is Black Spot, and it is caused by a fungus named Diplocarpon rosae. As its name already implies, this disease appears like black spots on the leaves and then the foliage turns yellow falling completely in early autumn, also as a consequence, the flowers lose the intensity of their color.
Black spot can be prevented by means of proper sanitation but also fungicide needs to be sprayed once or even twice a week during rainy seasons.
If you allow the soil to dry (for seven days or so), the rose will develop new roots looking for water and it won't be lazy! When applying water, you need to know that it has to be put on the soil around the rose bush and not on the leaves, if you water the leaves in the evening, the moisture can cause powdery mildew and your plant will then be infected.
In summer, keep a constant eye on your roses, checking them against disease, keep them fertilized (fertilizing period should stop in August) and watered as needed and you will enjoy their lovely and enchanting flowers for many years! If you take good care, the next year they will come back even stronger!