A 10-year-old rose bush near Washington, D.C. got a different disease each year: white stuff (mildew), black stuff (black spot), and now rust on it and a new climber 4 feet away. Sprays and fertilizing didn't prevent recurrence.
These are all fungal diseases. Use a dedicated fungicide (Funginex if available, or garden sulfur). Rust appears mainly on leaf undersides—spray there thoroughly. Some roses are genetically prone to rust and will get it whenever conditions allow.
Fungi develop tolerance to specific chemicals. Keep two different fungicides and alternate them yearly. This prevents resistance buildup.
Troubleshooting Leaf Loss on New Knockout Roses
Rescuing a Miniature Rose from Spider Mites and Black Spot
Gray Specks + Lacy Leaves on Knockouts: Sawfly/Rose Slugs
Diagnosing Yellow Leaves and Powdery Film on Climbing Roses
Reviving a Newly Bought, Pest-Ridden Rose Bush
Managing Black Spot on Roses in Wet Weather: Prevention and Treatment
Deformed Rose Leaves: Proliferation, Viruses, or Insects?
Identifying and Treating Rose Slug Damage on Container-Grown Knock Out Roses
Skeletonized Rose Leaves? It's Likely Rose Slugs, Not Caterpillars
Transplanted Wild Rose Not Blooming – Patience Needed
Bottom-Up Leaf Loss on Roses Near Detroit
Sudden Rose Leaf Drop: Stress Causes and Recovery Assurance
Yellow Leaves with Holes: Insects, Watering, and the Two-Knuckle Test
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