Disease-resistant roses do not resist the cure for diseases when treated. Disease-resistant roses are genetically modified to contain resistance to fungi. This motification has no effect on the application of further treatment.
Disease-resistant roses resist diseases differently than a pesticide or antifungal treatment. A disease-resistant rose is a genetically modified organism that has been altered in one of three ways. The first way to modify for resistance is to include genetic coding for enzymes that are harmful to fungal cell walls. The second is to enhance a plant's natural resistance to disease. The third method involves modifying genes in a way that causes the death of the infected area before the disease can spread.
Disease-resistant roses were developed in order to limit the commonly used year-round treatment involving toxic chemicals. Disease-resistant roses are most likely to be resistant to black spot on roses, rust mildew, and powdery mildew. However, a disease-resistant rose is not completely immune to disease. When a disease-resistant rose becomes infected, it can be treated in the same manner as a non-modified rose.
The first step in disease removal is prevention. Roses should be grown in well-drained soil, watered only during dry periods and mulched to maintain good drainage. If the plant still becomes infected, chemical treatments can be applied as directed.