In my garden, rust usually shows up if I slack off on the watering. It doesn’t show up on every rose, but certain ones will show rust in hot dry weather, without enough water. Abraham Darby, and Golden Buddha will rust anytime they get too dry. Once, I cut Abraham Darby to the ground, and cleaned underneath, and that took care of it. It was, nearly pruning time anyway. I have also picked off the rusted leaves of Golden Buddha, and increased the water. That was enough one time, another time I sprayed with an anti fungus mixture. I’ve heard rust is contagious, but so far, I’ve not had it spread to other roses. Could it be that your St. Cecilia needs a larger container? It’s getting pretty warm and dry about now. Lisa

Edited to add: I just noticed you already potted her up into a larger container. Sorry. Did the rust show up after that? Maybe her roots just need to get established into the new container, so she can take up water? Has anyone tried misting ( or spraying ) a rose with water when it’s so dry? I wonder if that would help or make things worse. I’d be inclined to try it, if all the rusted leaves had been removed. Lisa

In my garden, we have a handful of roses that rust on old foliage -- late Fall, say. I remove those leaves, and the plant does fine. I don't worry about those.

But I have had 1-2 roses over the years that rust on new foliage and continue to rust. That I won't tolerate, so those are long-gone.

In the case of your St. Cecilia, I would consider that the Austins, as a group, need more water than my Teas and Chinas (one reason I don't have more of them) so increasing the water might help her. Worth a try.

Thanks Lisa and Jeri! Lisa, I just potted so perhaps the roots have not really gotten enough water like both you and Jeri mentioned. I will make sure to water well and monitor the leaves to see if it returns. The newer leaves don't appear to have rust, so maybe I just need to give some good TLC! Thank you!

Great advice all around! I just wanted to add that ALL my roses become less suceptible to disease as they mature. Some are still prone and require very nurturing culture. Some grow out of it. Others have hit and miss stretches of various ills no matter how attentive I am, and almost every one of those has gone the way of Jeri's. (Yes, Abe Darby, I mean you. You'd better shape up, you adult baby!) Some flare up once in a blue moon but are otherwise fine. RdR had never rusted in my garden, but THIS year.... Don't forget to keep rusty leaves out of the compost! Carol

Thank you Lisa, that's a good point about the Santa Ana winds! And thanks for the encouragement Carol. I have not been growing roses for that long so hopefully as I put them in the ground they will mature better!

All of the above is valid. Some roses simply don't rust, even on very old foliage. Some roses rust only on very old foliage which rain would traditionally knock off. Some roses won't rust unless they are sufficiently dried out, then they rust until they receive the amount of water they need. Some roses rust as immature plants, then outgrow the tendency and are fine. Then, there are those which are simply NOT suitable for your climate and conditions because they are going to rust unless they are sprayed against it. If you want a rust-free garden, try to select those which don't rust, period. If you're willing to put up with more rust, but late in the season when "Nature" is "telling" the rose it's time to shut down for the winter, grow those which primarily rust in late fall into winter (when rust SHOULD be expected, black spot, too, for that matter, as Nature is using those diseases to knock old foliage off the plants, to shut them down for "winter"). If you don't mind the rust interruption due to water stress induced rust and/or if you use that to alert you more water is needed, grow those which rust from water stress. (the identical thing can be said for mildew. MOST roses can be forced to mildew, even in triple digit heat with single digit humidity, by drying them out too far.) All of those choices are yours to make and valid for what you wish to enjoy and endure. Yes, putting them in the ground can help...as long as the soil retains enough moisture and you provide enough to begin with. In Encino (Zone 10a) I was unwilling to provide the water demanded by the Austins planted there to prevent rust. None of the other roses planted in the area required those levels of water, so the Austins went away, one by one. Heritage was only healthy and only flowered when it rained. Otherwise, it had rust, black spot AND mildew and wouldn't flower. Ironically, I had Grey Pearl next to it and that thing actually grew (a little, but it GREW) and suffered no fungal issues, both without spray. When I notice rust and/or mildew and don't think it should be expected due to the conditions and variety they appear on, I bump up the water. In most cases, the fungi clear up. With those which haven't, I've used Jeri's and Clay's "iron cure"...a shovel!