Treating Downy Mildew on Established Roses: Spots and Holes on Leaves

Treating Downy Mildew on Established Roses: Spots and Holes on Leaves

White or gray spots that turn into holes on leaves are classic downy mildew symptoms. The fungus burns leaf tissue, causing the dead areas to drop out.

Treatment

1. Spray daily with 1 tablespoon baking soda in 2 quarts of water until spots vanish.
2. If ineffective, use Ortho RosePride Funginex Rose and Shrub Disease Control (ensure it's the fungicide, not the insecticide).

Treat promptly to prevent spread to other roses.