subject: How to Identify and Treat Rose Rust [print this page] How to Identify and Treat Rose Rust How to Identify and Treat Rose Rust
It is hard to see roses you've worked so hard on and come to like so much come down with rose rust. While the symptoms are alarming, and the disease can spread rapidly, there is plenty you can do.
Rust is largely a warm-climate fungal disease that affects all kinds of roses, even many of the modern hybrids, and occasionally even some of the roses that are billed as "rust resistant". If you live in a cold climate and spot rust on your roses, they have probably been shipped from a diseased state. Unfortunately, rust spreads rapidly and can be fatal -- unless you are certain of the health of your new roses, isolate them from existing beds until you are confident they are rust-free.
Rust first appears as reddish-orange spots on young stems and the underside of leaves. The spots often have a powdery appearance as well. The top sides of the leaves may appear yellow when they have rust underneath. If you leave rust on your roses, the spots will develop into warts and then turn black, ultimately defoliating the entire plant. Do not confuse rose rust with iron chlorosis, which is a common iron deficiency that can also cause yellow leaves.
Rust reproduces quickly, so any sign of it must be addressed immediately. Remove affected parts and dispose of them -- do not add them to your compost, no matter how hot your compost gets. You will just be growing more rust spores to attack your surviving roses.
To treat the disease and prevent it from spreading further, or from coming back, spray your roses with wettable sulphur on cool days and/or fungicidal soap. Sulfur does not kill rust, but it will prevent the next generation of spores from germinating. To prevent conditions that favor rust, remove fallen leaves and any other debris beneath your bushes, water at the base of the plant early in the morning, and space and prune your bushes to enhance air circulation.
Rust spores can survive the winter on leaves and canes, although a very cold winter will hurt their ability to thrive. A thorough autumn cleanup is essential in eliminating spores from your garden. You also need to be extremely careful about cleaning any tools or equipment you've used around the roses that were infected. It is not overkill to dip (or wash down) every tool you used before, during and after tending your roses with a 10% bleach solution. Be careful to keep the bleach, and the bleach solution, from dripping on the ground near your garden beds. The bleach will not do your roses any good.
Do not necessarily blame the garden center you bought the roses from for the rust problem. They bought them from a distributor, who bought them from a grower that had a problem. However you should definitely let your garden center know your roses came down with rust. They may ask to see a sample of the plant. Bring it in inside a plastic baggie that you have wiped down with a 10% bleach solution.
