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What Are the Orange Spots Under the Leaves of My Rose Bush?
What Are the Orange Spots Under the Leaves of My Rose Bush?. Rose leaves, when healthy, are glossy and green. The presence of orange spots on the underside of the leaves of a rose bush indicates that the roses have contracted a fungal disease. Rust is the most common fungal disease that produces spots on the leaves of rose bushes and other plants.
Rose leaves, when healthy, are glossy and green. The presence of orange spots on the underside of the leaves of a rose bush indicates that the roses have contracted a fungal disease. Rust is the most common fungal disease that produces spots on the leaves of rose bushes and other plants.
Fungal Rust
Fungal rust is a disease that attacks numerous plants. The common indicator of the presence of the fungus is orange spots on the underside of leaves. Rust is spread by spores that thrive in moist environments and rotting organic matter. As the fungus matures, the orange spots will turn black. Rust can defoliate an entire rose bush. This fungal disease is most common along the West Coast. Moisture is essential for the growth of this fungus.
Effects
Rust spreads over the leaves it affects, moving onto other leaves and even the stems or canes of the ruse bush. As the fungus develops, the rust spots grow larger and form groupings of wart-like spots. The fungi produces spores frequently throughout the summer -- and has the potential to destroy a rose bush and move on to other garden plants as well. Once autumn arrives, the fungal spots turn black and remain in decaying leaves until the following year.
Physical Controls
Stopping fungal rust from destroying a rose bush is a challenge, because the fungus thrives in moist environments and continues to attack the plant as long as spores are present. Water the bush in the morning to allow the leaves to dry; the fungus thrives on damp leaf surfaces. Remove any affected leaves immediately to remove the spores from the garden. Keep the soil free of organic matter like leaves that the fungus could feed on.
Chemical Controls
Fungicides help control the effects of fungal rust diseases by killing off spores and preventing the fungus from damaging the rose plant further. Fungicides are available at many garden centers, where experts are available to help gardeners choose the most effective chemical. Apply fungicides to rose bushes according to the directions on the package, to prevent harming the plant with excessive chemicals.
