Q: I noticed some white stuff on the leaves and flowers of my rose bushes, what is that?
A: What you are seeing is powdery mildew. Powdery mildew is fairly common in Santa Fe due to our hot days and cooler nights, which allows the mildew to grow on certain plants.
Some roses and other plants have been selectively bred to resist powdery mildew. The best way to take care of it is to go to a local nursery and buy some neem oil or garden strength hydrogen peroxide and follow the instructions on the package.
Although powdery mildew will not kill the rose, if is not treated it can affect the growth of the plant and prevent a the roses from blooming.