If you notice your succulents starting to look as though they have been sprinkled with flour, they might have powdery mildew.
Powdery mildew is one of the most common succulent problems. It is a fungal disease that coats the stems and leaves of plants and succulents with a white or grayish-white powdery substance. When the case of powdery mildew becomes too severe, it can spread to the bugs and flowers.
In this article, we will discuss what exactly causes powdery mildew and how to properly remove it from your succulents.
What is powdery mildew?
Powdery mildew is a fungal disease that affects a lot of different plants, including succulents. It can be caused by many different species of fungi, with different species attacking different plants. Other than succulents, powdery mildew can affect legumes such as peas and beans, nightshades such as roses, peppers, eggplants, and tomatoes and cucurbits such as melons, cucumbers, pumpkins and squash.
When your succulent gets taken over by the fungus, the spores of the powdery mildew will form a layer on top of the leaves.
Unfortunately, it is quite easy to infect other nearby plants, because if the spores get blown by the wind, they can be carried over to your other plants.
The powdery mildew caused by the fungus can stunt the growth of your succulent. It may not kill your succulent no matter how severe the infection is, but it can definitely cause its leaves to turn yellow and to wither.
How do I know if my succulent has powdery mildew?
The most important step in removing and preventing powdery mildew is to learn how to identify it. Being able to catch it in its early stages will help you treat it and make sure your succulent is minimally affected.
Powdery mildew will first present itself on your succulent as powdery white, circular spots on the leaves and stems. Over time the spots will spread across the upper side of the leaves, slowly making their way to the bottom of the leaves. Before long, your entire succulent will look as though it was dusted with flour.
The youngest leaves or foliage are the quickest to be affected by the powdery mildew. The longer the fungus is left alone, the more the leaves become disfigured, twisted, and even broken.
How does powdery mildew spread from plant to plant?
As mentioned above, powdery mildew is transferred from one plant to another through the air. The spores that were on an infected succulent can drift in the air, across your garden, and onto your other plants.
In some cases, you might think you no longer have powdery mildew on any of your plants, but unbeknownst to you, dormant spores can cause new outbreaks.
Powdery mildew flourishes in warmer climates and will thrive and spread quickly in dry areas with temperatures that range from 60 to 80 degrees Fahrenheit. In colder and wetter areas, the spores are not able to spread as efficiently. The fungus also prefers to infect plants that have more shade, compared to those that are out in the sun, because temperatures higher than 90 degrees Fahrenheit can slow the spread too.
How to control powdery mildew
You can use protectant fungicides on your succulents. Examples of protectant fungicides are potassium bicarbonate, neem oil, lime-sulfur and sulfur. These types of fungicides will work best if sprayed on your succulents in the early stages of the infection or as a strict preventative fungicide.
If you are apprehensive about using chemicals in removing powdery mildew, you can give baking soda a try. When you mix baking soda with a non-detergent liquid soap and water, it becomes an effective preventative fungicide. Spray it on your affected succulents or on your unaffected succulents once a week to reduce the incidence of powdery mildew. Making sure your plants are spaced apart properly can also help prevent powdery mildew from spreading.
To make the solution, mix together one gallon of water, half a teaspoon of non-detergent liquid soap, and one tablespoon of baking soda. Transfer the mixture into a spray bottle and spray your succulents enough to coat all of its outside surface areas with the solution. Do not forget to spray the bottom of the leaves.
Be sure to discard any leftover mixture. Despite being effective, the solution can be quite strong and burn your leaves. Make sure the plants are watered well days prior to spraying the solution and do not apply the solution while the sun is under direct sunlight.
If your succulent has become far too infected, it may be too late to rid it of the fungus. You will be better off discarding infected plants as well as their leaves, stems, and fruit. Make sure you throw them away properly as these spores can stay dormant for some time. Do not place the infected plants in your compost.
How do I prevent powdery mildew from infecting and spreading amongst my succulents?
When choosing new succulents, choose those that are resistant and less tolerant of powdery mildew.
Do not overwater your succulents to reduce the humidity.
Prune your plants that are overcrowded to promote better air circulation. Better air circulation means less possibility of infection.
Make sure you clean and sanitize your pruning tools after each use.
Remember to remove any affected foliage and to dispose of them properly.
Spray your plants with preventative fungicides.
Ideally, water your plants in the early morning, so it has a chance to dry throughout the day.
Do not put your susceptible plants in shaded areas and place them in a place where they can get direct sunlight.
Make sure the soil is able to drain excess water properly because the fungus loves humidity.
The white powdery stuff on succulents is called powdery mildew and is caused by different kinds of fungi, depending on the plant it is infecting. This plant fungal disease manifests itself as white spots on your succulent’s leaves first before it spreads its ways all over all the leaves, stems, and flowers.
Image: istockphoto.com / Svetlana Glazkova