How is rust on succulents treated?

Rust is a fungal disease

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Cacti, succulents and plants with caudex are generally quite resistant to pests and diseases, but sometimes carelessness weakens them, thus attracting various microorganisms, such as certain Puccinia and Melampsora, fungi that you will surely know. better by its common name: roya.

This fungal enemy does not care what type of plant to infect; in fact, it is one of the most frequently seen in gardens and, unfortunately, also in collections. But do not worry: there is a lot you can do to keep it away from your succulents .

What is rust?

There are many fungi that cause rust, such as Melampsora

Also known as black rust, is a disease transmitted by various fungi that live on the ground, or they can even be on the substrate as well. Like all of his family, hot and humid environments, so they are much more active during spring and summer.

But still, don't let your guard down: a winter with mild temperatures and excessive watering can make any succulent sick.

What are the symptoms?

The most common symptoms are the following:

  • Appearance of very small bumps and of almost rounded appearance of brown-orange or reddish color. We would see these in the body of the cactus, or in the leaves and stems of succulents and plants with caudex.
  • Fall of leaves, but only if the attack is severe.
  • Growth slowdown. It is difficult to see it in species that already grow slowly, such as Ariocarpus agavoides, but on the contrary, it could be noticed in others such as those of the Aeonium genus.
  • Sometimes, flowering out of season. It is rare in succulents, but when a plant is very sick, it can expend all its energy in flowering to try to leave offspring.

How is it treated?

Chemical remedies

It is important to clarify that today there is no chemical fungicide that serves as a curative. This means that the products that we will find in the nurseries will be useful to control the disease to the point of reducing the symptoms and thus ensuring that the immune system of the plants can keep them at bay; but nothing else.

They will be healthy for a while, but at the slightest sign of weakness, they will have symptoms again. If the comparison is allowed, the same thing happens with the common cold that we all have sometimes: we are healthy for a few months, but there is a drastic drop in temperatures (for example) and the only thing we have are medicines that relieve our symptoms, but they do not heal.

So, having said that, what product to use in case succulents have rust? Well then, the most advisable are those containing oxycarboxin, for its rapid effectiveness. Of course, you have to follow the instructions that are specified on the container to the letter, do not apply it if the plant is exposed to the sun (wait for sunset) or on windy days, as well as put on rubber gloves to protect yourself.

Home remedies

Powdered sulfur is a good fungicide

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If we prefer to use homemade or natural products, copper or sulfur powder is highly recommended. Both are highly effective natural fungicides, so much so that in nurseries it is becoming easier to find products that contain one or the other that can be used in organic farming.

In any case, it is probably cheaper to buy them directly from garden stores (not nurseries), or from those that sell a little of everything.

There are two modes of use:

  • One is to spray / sprinkle the plant to be treated with water and then sprinkle the copper or sulfur over it, as if we were adding salt to a salad, avoiding excesses.
  • And the other is diluting one or two tablespoons of copper or sulfur in 1l of water and spraying the plant.

In any case, you have to try to do it on days when there is no wind, and always having the specimen to be treated protected from the sun (that or, as we said before, wait for sunset).

It is also highly advisable to pour a little on the substrate and then water.

Can it be prevented?

One way to prevent rust is by planting the plants in pots of a suitable diameter.

No disease can be 100% prevented, but it is true that when we talk about succulent plants there are some measures, taking them will help us to make them healthy. These are:

  • Water only when necessary, allowing the substrate or soil to dry between waterings.
  • Do not over water, as they rot easily this way.
  • In the case of having them in pots, use substrates with good drainage, which filter the water as quickly as possible. Also, you do not have to put a plate under them.
  • If we are going to plant them in a rather compact soil, the ideal thing will be to make a large hole, and fill it with black peat mixed with 50% perlite for example.
  • Fertilize throughout the growing season, since to be really healthy they need water but also food. We will use specific fertilizers for cacti and other succulents, or blue nitrophoska.
  • You have to make sure they have the space they need to grow. In the garden, you should not plant two large species together for example; And if they are grown in a pot, you have to remember to transplant them to a larger one every 2 or 3 years.

With these tips, the rust won't bother the succulents much 😉.

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  1.   Lilac Aguilera said

    I love the tips that I read and so I learn to take care of my cacti and succulents thank you very much

    1.    Monica sanchez said

      We're glad you like them, Lila 🙂

  2.   Noemi said

    Hello, my cactus has rust on one part and how do I cure it?

    1.    Monica sanchez said

      Hello Noemi.

      How often do you water it? It may be watering too much and that is why that mold has come out. It is important to water when the soil is dry.


  3.   Ana said

    Good. I have a small cactus that has rust. I want to treat it before transplanting it into a decent pot. I have other young cacti and I don't want them to get contaminated. Can you recommend me how to treat the patient and how to avoid contaminating the rest? I would attach a photo but it does not give that option. Thanks

    1.    Monica sanchez said

      Hello Ana.

      Rust is a disease caused by fungi, so I recommend applying a fungicide that contains copper.