What is your tolerance for insect damage and fungal disease on roses?
It is a personal question and the answer can change depending on the uncontrollable factor of weather or the amount of time you have to devote to roses or your personal philosophy of what is the right way for you to garden.
I prefer to not use insecticides in my garden because I have fruit trees and mason bees that I nurture for pollination of my fruit. When aphids come to visit my roses, I often see ladybugs working on them, but I often get my hose with a medium spray nozzle and blast aphids with water for a few days in a row. The aphids fall to the ground and since they cannot fly, most do not return. If they are not removed, aphids continue to reproduce and damage roses.
If we have a hot dry June and July and I suspect spider mites will be active. Again, get the hose out with a spray nozzle. Spraying water and a slight rubbing of the leaves, especially on the undersides will deter the spider mites. So the word “spray” is not a bad word in my garden. I spray water, I spray liquid seaweed, I have been known to spray chelated iron and products approved for organic gardening.
Fungal diseases can do a lot of damage is a relatively short period of time. Once you see the damage, you cannot return the foliage to perfect again. As soon as a fungal disease shows, it is best to trim off (not tear off) the disease and do what you can to stop it from spreading. Some roses are resistant to fungal disease by hybridization. That is why you may see one or two roses badly defoliated (in a public garden for example) while others in the area stay clean.
The photos are examples of the continuum of possibilities for your rose garden. The amount of time you have to spend in the garden may change from year to year. Do not get discouraged if pests and disease appear. Contact a local Consulting Rosarian for help.