The fungal spores that cause rust are spread on the wind, and they can survive over winter on the soil surface, on fallen debris and even objects such as fences and stakes. The symptoms spread in early summer from patches of orange on the stems and leaf stalks of roses to more obvious orange speckling on the leaves. This can lead to leaf fall. In late summer, look out for black pustules on the leaves. Learn more about rust and hollyhock rust.
Orange speckling on rose leaves in early summer, sometimes causing the leaves to drop, is followed by black pustules on the leaves in late summer. By autumn it’s almost inevitable that the leaves will drop off.
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Promptly prune out any infected stems and destroy them, along with any infected leaves. Grow roses with lots of room around them so the air can circulate, and prune out any congested growth.
Use a preventative copper fungicide in spring before the overwintering spores strike. Make sure you cover all the leaf surfaces.