As fall arrives and as the days shorten, you may start to see rust on your rose leaves. Rust is an airborne disease that is prevalent in the fall. (Note: if you see rust in your garden, that means it’s time to prune. Don’t wait for January—call now for an appointment!)
Thanks to Clair Martin, author of 100 Old Roses for the American Garden, for his expertise on rust. Here is what he says:
Seeing red pustules on the underside of rose leaves? That is Rose Rust and is usually more of a problem in our Fall weather. For some reason we are seeing some Rust in the garden earlier than usual. Rust is another problem caused by a fungus; there are nine species of the rust fungus Phargmidium that attack roses. Spores that are carried by the wind spread funguses and when conditions are optimal, they infest our roses. Wet leaves for two hours or more and temperatures between 64° and 70° are enough to get Rust established on our roses.
If the infestation is light simply pick off the infected leaves and dispose in the trash. Again, planting with full sun and spacing bushes so that they are not crowded will help but if a particular bush seems to be infested year after year then prune with the shovel and dispose of your ‘Typhoid Mary’! The home remedy mentioned under Powdery Mildew will help, but again, if you must resort to chemicals then check with your Agricultural Advisor or a nursery for their recommendations.