Powdery mildew is a common fungal infection on succulents. It often appear as gay or white powdery spots on leaves, stems, and flowers. Although rarely fatal, this disease can cause serious harm to your plants. Sometimes the affected plants can become stunted or completely distorted.
Without intervention, powdery mildew can cover the whole plant, resulting in a reduced amount of photosynthesis that takes place. This can deny the plant sugars and important nutrients for survival. Therefore, it’s important to identify it early enough and treat it as needed.
Powdery mildew on succulents identification
There are various plant conditions that can be mistaken for powdery mildew. White fuzz on succulents can also be a result of mineral deposits, mealybugs, or the natural epicuticular coating that is also known as farina. However, powdery mildew is the easiest to identify.
Powdery mildew will mainly affect the upper part of the plant. Infected plants will look as if they have been dusted with flour. The fungus might cause some leaves to twist or become distorted. As time progresses, the affected plant may turn yellow and dry out.
Powdery mildew thrives in humid conditions, above 70% but its spores spread faster in warm, dry windy weather. This is why the disease is prevalent in greenhouses or in plants grown closely together. Infections are also common in plants that are stressed due to overwatering or insufficient sunlight.
Treating powdery mildew on succulents
Treating powdery mildew on succulents can range from the use of natural sprays to chemical fungicides. Before you treat, isolate the affected plant to prevent the disease from spreading to other healthy plants.
Relocate the plant to a place with relatively the same growth conditions as before to avoid causing it more stress.
The next thing is to inspect the nature of the damage. If just two or three leaves are coated with the powdery mildew, remove and destroy them. And if more foliage or the whole plant is affected, think about treatment. Removing too many leaves can harm the plant and it may not easily recover.
If you are dealing with small to moderate infections, I recommend you try natural sprays. They are made from natural ingredients and this makes them less toxic and friendly to the environment. Some of the most effective natural treatments include the use of the following:
Neem oil or insecticidal soap
Neem oil or insecticidal soap is highly effective in the management of mild to moderate cases of powdery mildew. You can mix the two to enhance their effectiveness. Just take 4 tablespoons of 1% neem oil and add to one gallon of water. Then add two tablespoons of your preferred insecticidal soap and mix.
It is important to know that, neem oil and insecticidal soap can be harmful to some plants. So, test the mixture on a small part of the plant and give it 24 hours to see the outcome. If there is no damage, spray your plant completely covering the affected sections.
Reapply the treatment in 7 to 10 days. Be patient as it may take about two weeks to see results.
Baking Soda (Sodium bicarbonate)
Sodium bicarbonate (baking soda) is also effective in getting rid of powdery mildew that appear established. Mix one teaspoon of baking soda per liter of water and add a few drops of insecticidal soap. Spray the solution on both the upper and lower leaf surfaces. Repeat the treatment in 7 to 10 days.
Potassium bicarbonate also kills powdery mildew on contact. To make the organic fungicide, mix one tablespoon of potassium bicarbonate in a gallon of water and add a few two drops of mild liquid soap. Stir to mix and spray gently on the leaves and stems of the plant.
Copper and sulfur-based fungicides are effective in controlling powdery mildew and other fungi infections on succulents. Chemical treatments are only recommended when dealing with severe cases of powdery mildew. Make sure to use as directed on the product label.
Powdered sulfur can also be diluted into a solution and applied as a preventive control on susceptible plants. It is effective in preventing the fungus spores from germinating. This treatment can damage plant tissues in hot temperatures. So, don’t apply it when daytime temperatures are above 90 degrees F.
It is important to use chemical fungicides away from children and pets. They can cause a risk to health when inhaled or ingested. Chemical fungicides can also kill pollinators and other beneficial insects. Always use them as a last resort when other natural options are not working.
Preventing powdery mildew on succulents
Prevention is the best control for powdery mildew and other fungal infections in plants. The following are helpful tips for keeping your plants healthy throughout.
- Inspect your plants regularly for signs of powdery mildew and other problems such as pests and diseases.
- Place your succulents where they will get enough sunlight and keep humidity on the drier side.
- Collect and destroy any fallen leaves or debris from infected plants.
- Avoid overfertilizing your plants as new growth tend to be more susceptible to powdery mildew.
- Isolate the affected plant from other healthy plants to stop the spread of the infection.
- Increasing air circulation around plants by pruning or planting them apart.
- Water your plants from the bottom especially when the air is warm and dry.
- Treat powdery mildew as early as possible before the spores can spread.
- Do not compost any infected plant parts as the spores can still be spread by the wind to your healthy plants.
Succulents are beautiful plants that are easy to grow and maintain. Powdery mildew is one of the challenges you are likely to deal with if succulents are not provided with proper growth conditions. This fungal disease can cause health and aesthetic concerns.
White coating on succulents is not always the problem of powdery mildew. It could be a farina coating, mineral deposit, or mealy bugs. If you are not sure of what’s the white stuff on your succulent, seek help from a nearby nursery or plant specialist for identification.
My name is Diane M Lewik, and I am the founder of this website. I am a degree holder in plant biology from the University of California – Berkeley. Over years, I have cultivated a vast collection of succulents and I have learned a great deal about how to grow and care for these unique plants.