Leaf rust is a disease that attacks garden plants in wet, humid conditions. It is common on roses, snapdragons, hollyhocks, crabapples, and daylilies. Rust diseases produce raised pustules that rupture to release powdery, orange to red-colored spores on the underside of affected leaves. Light yellow spots can be seen on the upper leaf surface directly opposite the rust pustule on the bottom side of the leaf.
What To Do and Helpful Tips
- Wet plant leaves encourage many fungal diseases, including rust. Apply water directly to the root, like with a soaker hose, to help prevent the disease, or water in the early morning so the leaves will dry quickly during the day.
- Remove and destroy any infected plants to prevent the spores from spreading. Do not compost diseased plant material.
- Select rust-resistant plant varieties and space the plants in the garden as recommended. Good air flow can help prevent many common garden diseases.