How to Detect and Prevent Rust in Plants
- 1). Look for rust on the undersides of foliage. It's orange in color and has a velvet appearance.
- 2). Remove any infected leaves immediately and discard.
- 3). Rake up and destroy all fallen leaves and debris. Do not compost.
- 4). Avoid overhead irrigation. Rust spores are carried back up to the plant by splashing water. Apply water at the base of the plant to avoid splash back.
- 5). Protect plants from high humidity and heavy rainfall. Place susceptible plants under overhangs or eaves to prevent wetting the foliage.
- 6). Water in the early morning hours so the plant has a chance to dry during the day.
- 7). Clean tools used to prune infected plants with a 1-to-1 bleach/water solution to prevent spread of disease to other plants.
- 8). Spray plants with sulfur-based fungicides. After dormant-season pruning, spray with a lime/sulfur spray or a Bordeaux mixture to kill overwintering fungus spores.
Source...