DIY Natural Fungicide for Cacti and Succulents

Fungicides are helpful in controlling and even preventing fungal infections in plants. Often, cacti and succulents are prone to fungi when grown in damp or poorly lit conditions. Getting leaves wet when watering and poor air circulation also increase the chances of an infection.

Many fungicides made from chemical compounds can cause serious damage to plants and animals, especially when used without following the directives. Some have caused burns on the foliage, while others have affected the lives of beneficial organisms in the soil.

I have successfully used natural fungicides to treat common houseplant fungi infections, including powdery mildew, root and crown rots, grey mold, and leaf spot, among others.

Natural fungicides are not only less expensive but also safe around mammals. However, you must use them repeatedly to remain effective. 

Natural fungicide for cacti and succulents

The following are some of the effective homemade fungicides for cacti and succulent plants.

Neem oil

Neem oil is found in the seeds of a mature neem tree. It is a yellow to brown substance with a bitter taste and sulfur-like smell. This natural oil has been used for hundreds of years to control pests and fungal diseases. Neem oil contains Azadirachtin as the active ingredient. 

Unlike chemical pesticides, neem oil is rapidly broken down by light, water, and microbes. It is practically non-toxic to bees, plants, birds, and mammals. This oil is even used in toothpaste, cosmetics, soaps, and traditional medicines around the world.

How to use

Neem oil is typically sold as a concentrate. So, to use it as a fungicide, you must dilute it with water and apply it as a foliar spray or soil drench. A good rule of thumb is to follow the manufacturer’s instructions on the label for the right dilution ratio.

For treating fungal infections on plants, I usually mix 1-2 tablespoons of neem oil per gallon of water. You may add a small amount of liquid soap to act as an emulsifier. Use a sprayer bottle to evenly cover all plant parts, particularly areas showing symptoms of the infection. 

The best time to apply neem oil is in the early morning or late afternoon when the sun is not hot. Applying during hot temperatures like those that come with hot midday sun can burn the leaves of your plants. Repeat the application every 7-10 days.

Tip: Test your neem oil solution on a small part and let it sit for 2-3 days before applying on the entire plant. Do not use it if it causes leaf burns or any other kind of damage.

Milk spray

Milk spray has proven effective in treating powdery mildew and other fungal diseases. In a recent study by the University of Connecticut, a spray made of 40% milk and 60% water was as effective as chemical fungicides in managing powdery mildew on pumpkins and cucumbers.

However, scientists are not sure yet how milk sprays work in suppressing fungal infections. 

Milk treatments should only be applied in the early morning or late evening. In order to be successful, you must apply it in bright light and repeat every 10 days or so.

It does not matter if the milk you use is skim or whole because it is believed that it is the protein rather than fat that interacts with the sun to create a brief antiseptic effect. On the downside, some gardeners have suggested that milk spray gives a bad odor, but this has not been my experience.

Baking soda

Baking soda is more of a preventive than a cure. Research has shown that Sodium bicarbonate solutions create pH conditions hostile to the growth of mold and other fungal species, which germinate best under acidic conditions. Baking soda solutions are significantly more alkaline.

To use baking soda as a fungicide, dissolve one teaspoon into one liter of water. You may add a few drops of insecticidal soap or liquid soap to help the solution spread and stick to the leaves. Stir the mixture and pour it into a clean spray bottle.

When applying, spray evenly to cover both the upper and lower leaf surfaces. Repeat the application every 5 to 10 days to control the fungal problem effectively.

How to prevent fungus on your cactus and succulents

Notably, some types of fungal infections have no known cure. Therefore, it’s best to prevent fungus than offer a treatment. Here are some helpful tips for keeping your succulents free from fungus.

• Do not overwater your plants, as it can cause stem or root rot. Waterlogged soils can encourage the growth of fungi that cause roots to rot.
• Maintain adequate space between your plants. This will provide good air circulation, carrying away the excess moisture.
• Water your plants near the base to prevent getting the leaves wet. Bottom watering rather than overhead watering is the best for preventing fungus.
• Clean and sanitize your garden tools to avoid the spreading of spores and other pathogens.
• Consider inspecting your plants regularly and treat any fungal infections early enough before they spread and cause extensive damage.

Final thought

Fungus can be one of the persistent issues facing succulent plants, particularly those grown in damp or humid conditions. Fungus can cause issues like crown or root rot, yellowing, wrinkling, and generally poor growth. Using the right fungicide can be beneficial to both plants and animals.