There are thousands of species of rust that attack different kinds of plants, and not all fungicides that fight rust can be used on all plants. Some of the different fungicides cannot be used on the same plants within a certain time frame or the combination of the two can burn the foliage and can even kill the plant, and some of the things you'd use for rust can damage plants if used in hot weather, so......just be sure you read the fungicide label and make sure the one you buy can be used on azaleas in high temperatures. Most product labels can be found on the internet by Googling so that you can read them before you even go to the store to buy a fungicide. The products most commonly used for various kinds of rust are organic products like sulfur (available as both a dust and a liquid), neem oil, and copper and then there's the whole group of synthetic herbicides like chlorothalonil (found in products like Daconil and Ortho Max Garden DIsease Control) and mancozeb. I imagine that chlorothalonil is labeled for use on azaleas, but I haven't grown azaleas since the 1980s so I don't know that for sure. You also can use bordeaux mix for azalea rust, but I don't know if you can use it when the weather is as hot as it is now

Whenever you have rust on anything, the standard method of treating it is to remove the rust-infected leaves so they do not continue to reinfect new foliage and to spray with a fungicide labeled for rust control on that specific type of plant. Also, rake up any rust-infected leaves that have fallen to the ground. Understand that once you have rust, it is hard to cure it in the current season. The use of fungicide sprays on a regular basis (most product labels will specify the interval of days in between spraying, and it can vary from 7 to 10 or more depending on the product) can keep the rust under from spreading and getting worse. Most fungicides work in one of two ways: either they coat the leaves (so be sure to spray the undersides of all leaves too) so new fungal spores cannot attach to them, or they change the pH of the leaf surface and make it a pH that is not in the right range for the rust to grow.

If I had rust on azaleas this year, I'd spray this year to keep it under control this summer and autumn, and then I'd spray preventively with a fungicide in spring to try to keep it from reappearing and establishing itself next year. With most garden plants, spraying preventively is more effective than beginning a spray program after fungal diseases already have shown up,

So far this year, I've only had rust on hollyhocks and beans, With both, I just kept removing the diseased leaves so it wouldn't spread to new foliage. The beans put out lots of new foliage and the rust stopped being a problem after we went a week or more without rain. The hollyhocks never really cleared up, and I didn't spray them with anything because it was raining daily for so long. I've cleaned up the rusty hollyhock foliage now, and we've been dry for a while, so I'm hoping the cycle of rust infection on the hollyhocks has ended for this year.

Now, since there's so many different kinds/brands of products that contain sulfur, copper, neem, chlorothalonil and mancozeb, it would be hard to guess which products will be on the store shelves in any given area at any given time. I often find it easier to find a fungicide at this time of the year in a full-line nursery or at an ag farm supply store like Tractor Supply or Atway's. At big box stores like Wal-Mart, you often can still find neem oil or Daconil in July if your store hasn't already started shoving gardening products out the door to make room for school supplies. Because there's so many different kinds of products available, (the TSC near me carries the Southern Ag brand), I found a document from Clemson that has a whole page that lists many of the available products for azalea rust....it lists them by brand names under each category. I've linked that document below.

Hope this helps,

Dawn

Clemson Univ Document on Azaleas

thanks Dawn. What about on a blueberry plant? are those fungicides safe?

You're welcome, and with regard to the blueberry plants, I have no idea. Blueberry plants are very difficult to grow and there's not many fungicides labeled for use on blueberry plants for rust. If a fungicide is not specifically labeled for use for a specific disease on a specific type of plant, it shouldn't be used on them. Many of the fungicides that are available to the general public are not labeled for rust on blueberries because they burn the blueberry foliage or damage the berries so can only be used on a very limited basis after the blueberries have been harvested, if they even can be used then.

Some formulations of chlorothalonil that are available to commercial growers are labeled for use for rust om blueberries but only in a very limited way, and these are not normally available to the home gardener and not affordable.

Serenade is an organic product used to prevent or at least control some fungal and bacterial diseases on many different kinds of plants, including ornamentals and edibles. The last time I used Serenade it was labeled for use on blueberries and it was labeled for rust control, but since I have alkaline soil and alkaline water, I don't even bother trying to grow blueberries, and I haven't used Serenade in several years. I don't know if it is still labeled for blueberries or for rust, but assume it is.

Maybe someone like Scott who does grow blueberries will see this and respond, but you might need to post the blueberry rust question on its on thread with 'blueberry rust' in the title, so people will see it and respond. Since the title of this thread was "Azalea Rust", people who don't grow azaleas might skip the thread and never see that the question also applies to blueberries.