Powdery Mildew on Roses
Powdery mildew on roses appears as a white powdery mold on the leaves and buds. After contracting powdery mildew roses will drop their leaves prematurely. Take precautions to prevent rose mildew from spreading to your fruit trees.
common rose diseases.
It is caused by several different fungi, Sphaerotheca pannosa being the most problematic as it can spread to and infect stone fruits growing near mildew infected roses.
Powdery mildew in roses will cause the leaves to pucker and wrinkle. Premature leaf drop is another symptom.
The best control is prevention.
Choose resistant rose varieties or at least avoid planting vulnerable varieties near stone fruits.
Causes of Roses Powdery Mildew
Roses growing in less than all day sun will be more vulnerable. Avoid overcrowding the plants. Use drip irrigation to water and avoid wetting the foliage as this can splash the spores onto other roses nearby.
Lime-sulfur sprays are effective against rose powdery mildew. Spray susceptible plants before growth begins in the spring. Reapply the control weekly during the growing season.
Avoid spraying the plants while the sun is on them or when temperatures exceed 85 degrees F. to prevent leaf burn.
Ortho Rose Pride is a 3-in-1 product that will protect against black spot, rust, and powdery mildew on roses. This provides a much better value than buying separate products for each disease.
If you would prefer an organic fungicide, Green Light is the one I recommend. The active ingredient is neem oil. It will control black spot, powdery mildew, rust, anthracnose, spider mites, aphids, and whitefly.
If you would like to try a homemade rose mildew spray, here is a recipe:
I have never tried this but the theory is that the baking soda raises the pH of the leaf surface making it inhospitable to the growth of mildew spores.
Growing Hybrid Tea Roses
The Green Rose