Roses need repeated applications of fungicides and insecticides to protect them from diseases and insects through the growing season. The three main rose diseases prevelant in the Pacific Northwest are black spot, mildew and rust. All three diseases can be controlled by systemic fungicides such as Propiconazole, Myclobutanil and Tebuconazole. Propiconazole is available in Fertilome Systemic Fungicide. Myclobutanil is in Spectracide Immunex Fungicide. Tebuconazole is in Bayer All-in-One Rose and Flower Care and Bayer Disease Control for Roses, Flowers and Shrubs. Propiconizole and Myclobutanil are applied as sprays to the leaves. The Bayer products are applied to the soil and taken up into the leaves from the roots. Systemic fungicides are translocated within the plant and stop disease development in already infected leaves as well as protecting new uninfected leaves. Daconil and Chlorothalonil are also widely available and effective, but are not systemic and therefore protect only new uninfected leaves. Organic gardeners can spray with lime-sulfur (calcium polysulfide), copper sulfate or Neem oil. Fungicides should be applied at 2 to 3 week intervals from April through October
The two major insect pests of roses are aphids and mites. They can be controlled with insecticidal soap or Neem Oil. I have been successful in controlling both insects and diseases with beweekly application of Neem Oil. Rotenone and Pyrethrin are two more organic insecticides which control aphids. Merit, Acephate and Imidocloprid are 3 systemic insecticides. Merit and Acephate are available in several different brands of insecticides. Imdocloprid is available in Bayer All-in-one Rose and Flower Care. This product also includes tebuconizole for diseases and fertilizer. Other rose pests such as rose chafer, rose midge, rose slug, and borers may require one of the systemic insecticides for control.