How to treat Fungal Infection in Fiddle Leaf Fig [Helpful Tips]

The last thing you want to see is your healthy fiddle leaf fig plant showing signs of fungal infection.

With so many possible causes, identifying and treating the fungal infection can seem daunting. However, don’t stress, because this article will cover how you can recognize fungal infection as well as how to treat and prevent the disease.

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Root Rot

The primary causes of root rot are poorly draining soil and overwatering. The latter is responsible for the death of many otherwise healthy fiddle leaf figs.

In most cases of root rot, the infection is caused by fungal mycelia which live in soil, coexisting with the plants.

The fungus usually stays in a dormant state and doesn’t pose a danger to the plant – until you oversaturate the soil.

Overwatering the houseplant cuts off its air circulation, allowing the fungus to proliferate and strangulate the plant by preventing the roots from breathing in oxygen. 

Here are a few ways of dealing with root rot in fiddle leaf figs:

  • In case of root rot above the soil, trim off the rotted sections of the root and treat the cuts with some powdered fungicide. If the rot is too much to cut out, you may have to discard the entire plant.
  • Reduce the watering frequency to treat the fungal infection. Always check the moisture level by performing a finger test before watering the plant. When misting the plant, ensure the water doesn’t get on the stem or leaves.
  • It is recommended to report the fiddle leaf fig and start afresh. Remove as much soil from the roots as possible without damaging them. Discard the infected soil and sterilize the pot before using it with the fiddle leaf figs.
  • Spray the fiddle leaf figs with houseplant fungicide. Ensure to follow the instructions as prescribed on the label. Repeat as many times as necessary.
  • Finally, if nothing else seems to be working, you might have to cut your losses and start over. The fungal infection may have reached an advanced stage that is too difficult to treat.

Fungal Infection Leading to Rust

Rust is more likely to occur in outdoor houseplants compared to fiddle leaf figs that are grown indoors.

Look for brown spots or rings on the leaves. They start on the underside of the leaves, but the advanced stages of the rust may appear on other sides.

If allowed to progress, the fungal infection will lead to the yellowing of leaves and will cause them to fall off.

Implementing good hygiene practices will prevent the spread of rust. Cleaning and disinfecting your gardening tools will also prevent it from spreading.

Once you have confirmed that your fiddle leaf fig has rust, your priority is to prune and discard the affected foliage.

Don’t compost them because you will spread the rust. If the removal of the affected foliage doesn’t resolve the problem and the rust continues, you may have to use fungal treatments.

Try using sulfur dust or copper fungicides to treat the affected foliage. Note that fungicides will alter the pH of the surrounding environment. This can kill the fungus but also affect the health of the plant.

Apply fungicides to your houseplants every week or so. And remember, keep the plants away from the sun after the application of fungicides to prevent leaf burn.

Sooty Mold

Sooty mold is a black fungus that grows on honeydew-covered leaves. Honeydew itself is a waste excretion produced by sap-sucking pests such as scale. 

Sooty mold thrives when the humidity is low. It can devastate fiddle leaf figs by blocking sunlight and disrupting the process of photosynthesis.

If allowed to progress, sooty mold can lower the growth rate of fiddle leaf figs and prevent them from reaching their maximum size.

The best way to deal with sooty mold is to get rid of the pests that are secreting honeydew on the leaves.

Look for pests crawling underneath the leaves and in the upper areas of growth. The treatment methodology depends on the type of pests that your fiddle leaf fig is harboring.

A powerful remedy is to use essential oils such as neem oil. These oil-based substances are extremely effective at suffocating pests that are plaguing your fiddle leaf figs in California.

You can administer the soil as a spray directly over the surface of the leaves. Neem oil can even prevent eggs from hatching.

Note: After the application of essential oils for pest removal, keep the plant away from direct sunlight to prevent burning.

Another strategy is to use insecticidal soap to get rid of pests. There are many DIY recipes for making one at home. However, you can buy them from an online store.

The soaps are ideal for removing honeydew left behind by scale and aphids, thereby stopping the growth of sooty mold dead in its tracks.

Finally, for advanced stages of infestations, you might be better off using pesticides. They should be used as a last resort because of their toxicity to the plant itself.

However, careful use of the pesticide should resolve the problems without killing the plant in the process.

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Powdery Mildew

Powdery mildew is the superficial growth of a fungal disease that affects the stems and foliage of fiddle leaf figs and most houseplants.

Most cases of powdery mildew are not fatal to plants, but you should intervene at the earliest to treat the disease.

If allowed to advance, the fungus will eventually compete with the plant for nutrients and cause the leaves to wither and die. This can make the houseplant look unsightly and vulnerable to other diseases.

Powdery mildew thrives in dry and warm environments. It is often mistaken for dust and dirt that can be swept away with your finger. But it always returns

Powdery mildew appears as white or gray spots on the leaves. There are many environmentally friendly ways of dealing with powdery mildew. Let’s take a look at a few methods.

Baking Soda

You can treat also treat fiddle leaf figs by using baking soda, a natural fungicide. To make the solution, mix one tablespoon of baking soda with one-half teaspoon of non-detergent soap into a gallon of water.

Pour this mixture into a spray bottle. Mist all parts of the plants with the mixture. Use a microfiber cloth to wipe down the plant’s leaves.

You will notice a difference in the appearance of the plants in a few days. There will be an improvement in the plant’s appearance, and the white spots will gradually fade.

Baking soda is also used for treating hard water spots on fiddle leaf figs.


You can also use mouthwash to effectively kill powdery mildew spores. The primary function of mouthwash is to kill germs, and the spores of powdery mildew can’t tolerate it.

Mix mouthwash with water in a 1:3 ratio to kill the spores. Avoid using mouthwash excessively because it is toxic to the plant.


Powdery mildew is often caused due to dry conditions. One way to treat powdery mildew is to make the living conditions of the plant undesirable for the spores by watering the leaves.

However, this method should be used sparingly because overwatering will lead to other issues for your fiddle leaf figs (such as root rot).


Anthracnose is a fungal disease that affects the soil of various houseplants, including fiddle leaf figs in California.

It is difficult to get rid of this disease if you are growing the plant outdoors. The spores remain in a dormant state in the winter and come alive in the summer months.

The fungal infection may infect your fiddle leaf figs for a number of reasons, including:

  • Allowing dead organic matter to affect the quality of the soil
  • Using a poor quality soil
  • Overwatering
  • Crowding

The most obvious place to spot the growth of anthracnose is on the leaves and veins. Infected plants will have small lesions on their leaves. The lesions are dark in appearance.

They look very similar to other leaf spot diseases. However, a closer look reveals small brownish dots that are smaller than a pinhead.

Here are a few ways of preventing anthracnose:

  • Sanitize your gardening tools before using them to prevent the spread of anthracnose spores
  • Spray neem oil all over the plant regularly
  • Ensure the plant receives optimal light, water, and fertilizer

If the above methods don’t get rid of anthracnose, the disease may have reached an advanced stage.

The best way to get rid of the disease is to dispose of diseased plant parts.

Prune off the diseased part of the plant using sterilized scissors and discard the material to prevent the spread of the disease. For stubborn cases of anthracnose infections, use chemical treatments.

Wrapping Up

Fungal infections can devastate fiddle leaf figs and are tough to manage. Since these plants already have stringent care requirements, the outbreak of infection may prove to be very stressful to the leaves.

However, as long as you provide your fiddle leaf figs in California with optimal conditions and preventive measures, you can nurse them back to health.

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