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White Fungus on Tomato Plants — Is It a Threat?

White Fungus on Tomato Plants — Is It a Threat?

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Tomatoes are perhaps one of the most commonly planted crops in gardens. As they’re relatively easy to grow, it’s not surprising that almost every gardener would want to have this crop in their yards.

But, what if you suddenly find some white fungus on your tomato plants? Should you worry too much about it?

Let’s get to know what this white fungus is on your tomato plants, and if they’re indeed harmful, learn ways to rid your plant of it.


White Fungus on Tomato Plants

The white fungus on a tomato plant is called Leveillula Taurica or Erysiphe lycopersici. It’s a powder mildew or mold which an damage or kill the tomato plants. The first step to removing the white powdery mold is to identify and know the causes so you can prevent it from coming back.


How to Identify which Fungus is Attacking Your Tomato Plant

Leveillula Taurica, Oidium Lycopersicum, and Oidium neolycopersicum. All three of these can cause a white powdery mold to appear on your tomato plants.

Each of the three kinds of fungus prefers a warm temperature, so that is your first step in identifying the mold species.

All three fungi like humidity. They also like wet leaves, so if you live in a warm, humid area, whether it is rainy or not doesn’t matter, because the morning or evening dew is enough to make the leaves wet.

You will first notice it starts to develop on your tomato plants. You will notice a bright yellow or light green lesion on the upper portion of the plant’s leaf.

As it progresses, the affected sections of the leaves will turn brown, and white mildew will appear.

If the fungus is bad enough, you will notice pieces of the leaf dying. In some severe cases, the entire leaf will die and fall off.

The lack of foliage leaves your tomato plant vulnerable to sunburned tomatoes and tomatoes that are much smaller than normal.

If you don’t mind eating fruit that has a fungus, you can still eat the tomatoes as long as they have not been treated with chemicals.


What Causes Mildew on Tomato Plants

Regardless of which type of mildew it is — Leveillula Taurica, Oidium Lycopersicum, or Oidium neolycopersicum, the conditions must be favorable for the growth of the mildew.

All three of these molds need healthy living plants to grow. Remember fungus grows and multiplies.

This is an issue and an inconvenience for individuals who grow tomatoes for their own use. It’s a big problem for companies who grow tomatoes to sell.

No one wants to buy a tomato the size of a large cherry.


How to Prevent White Fungus on Tomato Plants

One of the best preventative treatments is sulfur spray and sulfur dust. Apply the sulfur product on a calm day with temperatures that run below the 90-degree Fahrenheit mark.

Because sulfur will burn your tomato plants in direct sunlight, apply it in the morning or mid-evening hours.

Allow at least two weeks to pass after applying oils to tomato plants before using a sulfur treatment. The combination of sulfur and oils could cause more damage to your plants.

Another treatment option for your tomato plants is a bio-fungicide. Biofungicides are living species that limit fungal and bacterial activities that can result to plant disease.

Biofungicides, generally, are microorganisms that you extract from the soil that prevent plant diseases from reproducing.

Be sure to follow the instructions because you proceed working with biofungicides.


How to Treat White Fungus on Tomato Plants

Start treatment as soon as mildew appears. You should notice the powdery mildew on the plants being reduced and occasionally eliminated using horticultural oils and neem oils.

Oils should not be used during a drought if temperatures are over 90 degrees Fahrenheit or within a two-week period of using a sulfur product on your tomato plants.

After the treatment, completely cover the tomato plants after the treatments. Repeat the treatments every 7-10 days or after it rains.

Mildew becomes more resilient to Biofungicides and insecticides as it grows and develops. Experts suggest curing powdery mildew as soon as it occurs.

The quicker you get a jump on the fungus, the easier it will be to cure it.

Another way to keep tomatoes free of powdery mold is to analyze the dirt. When nitrogen levels are too high, the powdery mildew grows rapidly.

Also, give the tomato plants some space. Plant the tomato plants at least 24 inches apart so the air is able to move through the leaves and this will help prevent the fungus from spreading quickly.

In addition, stake your tomato plants so they get better airflow and circulation.

Keep the weeds out of the garden. Funguses spread quickly and easily through all types of plants.

Watering from above should be avoided. Fungi may spread quickly on wet leaves.

Drip hoses or even other in-soil watering systems should be used.

Fertilizer should be applied at regular intervals. Mildew is encouraged by increases in nitrogen in the soil, but regular feeding keeps levels stable.

Once the season ends, remove and eradicate any damaged plants. The fungus doesn’t really survive the winter in northern regions, although they can thrive in more temperate climates and in a greenhouse.


Frequently Asked Questions about White Fungus on Tomato Plants


How do my tomato plants get Leveillula Taurica, Oidium Lycopersicum, or Oidium neolycopersicum, the white powdery fungus?

Airborne spores fall on leaves and mature, causing the disease to spread. Powdery mildew is a fungal disease that feeds on the cells of tomato plants, producing yellow leaves and a white powdery growth of fungus.


Can I still eat tomatoes that have the powdery fungus caused by Leveillula Taurica?

Unlike what you think, you can still eat a tomato infested with the Leveillula Taurica fungus. If a fungicide was used to treat the tomato plants, you will need to wash the tomatoes well and dry them thoroughly before consuming them.


I have four tomato plants – two of them are near the end row of my garden and two are in the middle with cucumbers on the other side. The two tomato plants on the end have the white powder fungus on them but the two in the middle do not. Why?

The two tomato plants that are affected by the Leveillula Taurica fungus are in a position of easy access to blowing spores, so the spores can easily and on the leaves. It has a lot to do with the way the wind was blowing when these spores blew in. The two fungus-free tomato plants are not any better protected. They just got lucky!



Taking care of any type of plant can be hard work. You want your plants to thrive and when they are stricken with a fungus it makes it even harder to care for them.

Prevention, if possible, is the best way to go.