What Are The Common Croton Plant Diseases?

Crotons are one of the most popular plants for homes, offices, and gardens. Croton plants (codiaeum variegatum) are perennial evergreens from India, Indonesia, and Malaysia.

Colorful croton plants do experience diseasesPin
Crotons like high light levels for best results

This plant genus includes varieties with fancy names such as:

All bear the Crotons’ iconic variegated colorful leaf in a wide range of colors.

Croton plants are easy to care for, requiring direct full sun, or indirect light. Remember to avoid direct sunlight because it can burn the leaves.

In addition, give them moist (but not wet) soil or moderate humidity. Liquid or slow-release fertilizer every 6-8 weeks also works well.

They also strive in USDA hardiness zones 10 to 11.

As with any other tropical plant, misting is a good way to keep one healthy in the office.

Crotons are not immune to infections, infestations, or bacterial or fungal diseases like root rot and leaf drop. They fall prey to pests like mealybugs, spider mites, scale insects, bugs, and thrips.

In this article, we’ll dive deep into all the details of croton plant problems and croton fungus treatment.

What Are Some Common Croton Diseases?

It is rare for healthy Croton plants to suffer disease problems. However, there are some common diseases that other infected plants can pass to Croton plants.


Anthracnose is better known as bacterial leaf spot or leaf blight. It is a disease that will discolor leaves and causes dark lesions on leaves.

The disease creates tan-colored dead spots on the foliage. It can be highly contagious.

Bacterial spores can transfer from one plant to another as an infected leaf comes in contact with healthy, colorful foliage.

Crown Gall

It’s one of the nastier plant diseases out there. Crown gall comes from the bacteria Agrobacterium tumefaciens. This is a Gram-negative soil bacterium that injects part of its own DNA into susceptible plant nuclei.

This bit of T-DNA is carried in the bacterium on a tumor-inducing (or Ti) plasmid. It works by disrupting the normal growth and cell division of the infected plant.

Grafted or plants injured or propagated through stem cuttings are all highly susceptible to this infection.

Scientists have done a lot of research on this bacteria due to its potential benefits for genetic engineering.

The large galls it forms on a Croton plant transmit easily. Its ability to remain dormant for long periods in potting soil makes it a dangerous foe to the average plant enthusiast.

Nectriella pironii (AKA Kutilakesa pironii)

This fungal pathogen affects more than 62 known genii of plants, including Croton.

Symptoms involve brown-ringed, slightly sunken spots on the foliage.

In the center is a pink mass of spores.

In time, the infected leaves will turn brown and fall off.


This disease is the result of poor Croton plant care. Overwatering causes Oedema, as opposed to an infection.

The plant attempts to absorb more water than it can store, resulting in blisters on the plant’s leaves.

Failure to treat this condition may result in heavy leaf loss.

Details on: Crotons Losing Leaves

Powdery Mildew

If you notice a white powdery substance on croton plant, your plant likely has powdery mildew.

Powdery mildew is a common plant infection. The mildew resembles a layer of white spots on croton leaves covering both sides.

Within a few days, you will notice croton leaves turning white.

This white fungus on the Croton plant creates conditions causing stunted leaf growth over time. The mildew makes it far more than a simple eyesore.

Question: Are Crotons Poisonous?

How To Control Croton Diseases

Infected croton plants rarely need dumping. However, the exact treatment options vary depending on the disease.

Caring for an infected plant early on allows the best chances of a full recovery. It will also help prevent the diseases from spreading to other nearby plants.

How To Treat Anthracnose

Treating Anthracnose or croton leaf spot disease in one of two ways.

Carefully prune away each infected leaf. Be careful not to allow the leaves to touch healthy foliage. Dispose of the leaves. Sterilize your tools afterward.

Use sprays of copper-based fungicides on plants with heavy infections.

Copper fungicides like Bonide are easy to find. Follow the labeled directions to reduce the risk of:

  • Harming beneficial insects outdoors
  • Creating health risks for your family when treating indoor plants

How To Treat Crown Gall

K84 is an antibiotic used against the crown gall. It has been in use for several decades. K84 includes a non-pathogenic relative of the Agrobacterium tumefaciens bacterium.

K84 is most often used to treat seeds and may not be suitable for most infections.

The most common way to deal with infected plants is to remove and discard infected plants before the disease can spread.

Sterilizing or discarding the infected soil is also recommended.

How to Treat Nectriella pironii

Remove and discard any infected leaves, sterilizing all equipment used.

You may also use a broad-spectrum fungicide to combat this fungi disease.


This condition comes from a surplus of water. Treatment is simple. STOP watering the houseplant until it has had time to use or shed the excess water.

Moreover, ensure there’s an adequate drainage hole to allow water to run freely.

Adjust your watering habits to avoid a resurgence.

How to Treat Croton Powdery Mildew

Croton plants may love humidity, but so does the powdery mildew fungus.

For croton white fungus treatment, avoid getting the leaves wet and reduce the ambient humidity to dry the fungus out.

You can use neem oil or potassium bicarbonate to kill the bacteria or fungi.

Moreover, enhancing air circulation and maintaining low humidity levels and soil moisture can prevent powdery mildew.

Using a humidifier or pebble tray will help with this.

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