@Lynn, get a sprayer like the HDX from Home Depot and spray the soil around the Rose bushes as well as under the leaves with the Dawn detergent mix. The fungus is in the soil. When it rains the spores get splattered up to under the leaves. Water the roots also and feed them with Bone meal for root development. Every so often I would spray my garden by using either Dawn or Laundry detergent in a watering can.