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8 Most Common African Violet Diseases – Causes & Remedies

African Violets are compact, lovely houseplants that are kept in almost every household all around the world.

These plants are beloved because of their nice, velvety foliage and the little colorful flowers that can bloom for 10 to 12 months of the year.

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African Violets are easy to grow and they can be so grateful if they get the proper care. However, sometimes even these plants can be a headache.

And this happens when they get diseased. Fortunately, some of the diseases can be treated and all of them can be prevented with some extra care and attention.

In this article, I will talk about the most common African Violets diseases, their causes and treatment.

Bacterial Blight

Bacterial Blight is also called Erwinia. This name comes from the cause of the bacteria, Erwinia chrysanthemi, that causes this disease.

– Causes

Erwinia chrysanthemi can be spread by insects or dirty hands and tools.

Also, high humidity can encourage bacteria to thrive and spread.

– Symptoms

When bacteria are harming your African Violet, the first signs are soft, water-soaked and oozy spots on the leaves and the veins in leaves will become darker.

To check if it is really a bacterial disease, you can cut the leaf where these lesions are, and you will see gooey threads as you pull the leaf apart.

If the disease is spreading and not treated, then further symptoms will appear such as brown spots on leaves, the leaves will become pale and holes will be made by bacteria where the water-soaked spots were previously.

The late symptoms, when the plant is not treated, will become wilt and rotten and the whole plant will collapse and die.

The growth of the plant will be also stunted.

– Treatment and Prevention

To prevent bacterial infection, always use clean tools, wash your hands before touching the plant and keep the humidity at the right level.

Do not overwater your African Violets and avoid the leaves, whenever you water.

Over-fertilizing and too big changes to the temperature are also good to be avoided to prevent the bacteria to spread.

As a treatment, you should remove all the affected leaves and flowers. But sterilize your tool after each cutting.

Also, isolate all the affected plants to stop the spread of the disease.

Botrytis Blight

Botrytis Blight is another common disease when it comes to African Violets. This disease can also affect your other houseplants, so be vigilant if you notice this on your African Violets.

Botrytis Blight is also known as bud rot or gray mold. These names are pointing to the symptoms of the actual disease.

– Causes

This type of blight is caused by fungi, named Botrytis cinerea, and it is very contagious. It can spread quickly to the other African Violets.

These fungi will appear and thrive in moist conditions.

– Symptoms

The first signs of Botrytis Blight are discolored, gray blooms and the center crown’s stunted growth.

If the disease is untreated, this will spread to the leaves as fuzzy gray and brown growth on them and water-soaked lesions will appear as well.

The symptom of an advanced Botrytis Blight is a plant that seems to melt. Leaves are dark and flowers are faded, and the whole plant is wilt.

– Treatment and Prevention

As I always say: the best treatment is prevention. So, keep your African Violets well ventilated, don’t place them too crowded. Also, keep their soil moist, but not soggy.

However, if you see signs of Botrytis Blight on one of your African Violets, then isolate that plant as soon as possible. Remove the affected leaves and blooms, and then treat with fungicide.

You can still save the plant if you act quickly and the disease is not widespread.

Treat your healthy plants as well with fungicide and check them regularly to see if they have been affected or not.

If a plant is in a very bad shape, and the fungi are spread all over it, then you should discard that plant because it cannot be cured.

But don’t throw it into your compost bin as the fungi can remain in the compost if that is not especially kept at a high temperature.

Also, if you want to reuse the pot after you have thrown away the affected plant, you should clean it with a bleach solution to prevent the spreading of the fungus to the new plant.

Foliar Nematode

Foliar Nematode is also known as Leaf Nematode. This disease is caused by Aphelenchoides ritzema-bosi, which are microscopic, unsegmented worms that are feeding on the foliage of African Violets.

These little worms can be fatal for the plant, in most cases. Therefore, prevention is the best.

– Causes

As I said, this disease is caused by Aphelenchoides ritzema-bosi worms. They enter the leaves through pores or wounds.

– Symptoms

The main symptoms of the disease are swollen stem, shiny, brown and yellow spots on the underside of the leaves.

These shiny brown spots can be visible mostly between the veins and these usually have a red cast.

Other symptoms can be wilted leaves, that become pale and the growth of the plant will stop.

– Treatment and Prevention

As I mentioned above, in most cases, Foliar Nematode cannot be treated and will be fatal to the plant.

If the worms are not too many and spread in many leaves, you can try to remove the affected parts, if needed, all the leaves and repot the crown.

You should also keep the plant isolated, even after repotting.

Another treatment for Nematodes can be the use of Metasystox or Vydate, but these can be available for you ONLY if you have a pesticide license.

As prevention of spreading Nematodes to your African Violet is to use clean tools with clean hands.

Before repotting you can also pasteurize the soil and always use a disinfected pot.

When you get or you buy a new African Violet, you should always isolate the new plant until you are sure it is not infested.

Phytophthora Crown Rot

Phytophthora Crown Rot is a fungal disease that affects the crown of the African Violets.

– Causes

Phytophthora Crown Rot is caused by Phytophthora nicotianae and Phytophthora Cryptogea fungi that will cause the rotting of the roots and crown.

These fungi appear mostly when the African Violet is over-watered or has heavy and soggy soil.

– Symptoms

The most common symptoms of Phytophthora Crown Rot are that the crown becomes mushy and its color darker.

Other symptoms are the plant’s wilt, the leaves become translucent brown and have a jelly-like consistency.

Also, the leaves and the crown have a weblike substance on the surface, but you should not confuse this with the symptoms of the Spider Mites or Leaf Mealy Bugs.

– Treatment and Prevention

To prevent crown rot, you should keep the soil of the African Violet moist. Not too dry and not too soggy.

The pot should not be too big, and you should use a special potting mix for African Violets, that is not too heavy and will drain easily.

If your African Violet has Phytophthora Crown Rot, unfortunately, there is no way back, and the chance to save the plant is very low.

However, if you want to try to save it, you should first isolate the plant, if possible, put it in another room.

Next, you should remove all the dead or dying parts of the plant, such as leaves, stems and roots.

After you cleaned the plant, dust it with sulfur to stop the spreading of the fungi.

Then repot the remaining parts of the plant in fresh and sterilized soil and a small, clean pot.

Do not fertilize the plant until this grows big enough. Depending on the plant’s condition, this can take four to six weeks.

Powdery Mildew

Powdery Mildew is a fungal disease that is caused by high humidity and sudden changes in temperature.

– Causes

Powdery Mildew is caused by Oidium fungus. This fungus is thriving when the humidity is too high and the air doesn’t circulate well.

The sudden changes in the temperatures can also be the cause of this disease. For example, in the spring, the days are warm, but the nights are still cold.

Powdery Mildew, as its name says, is a powder-like, white and gray “mold”, that covers the leaves and the flowers.

If untreated, the affected parts will become white and then die.

– Symptoms

The typical symptom of the Powdery Mildew disease is a light gray or white, a powder that covers uniformly the leaves and flowers.

You should not confuse this with the Botrytis mold, which usually appears in spots and has a fuzzy appearance.

Other symptoms such as discoloration and deformation of the flowers can appear as well.

The plan also has stunt growth and later, the flowers will drop off.

– Treatment and Prevention

To prevent Powdery Mildew, pay attention to the air circulation and temperature changes. Try to keep them at a constant temperature.

Remove all the spent flowers and dried leaves, whenever you see them, so these are not spreading any pests or diseases.

If you always work with clean tools and hands, the pots are clean when repotting, you can also prevent many diseases.

As a treatment for Powdery Mildew, you can use Lysol on the affected areas. But before this, you should isolate the diseased plant.

If this doesn’t work in 2 days and you don’t see any improvements, then you can opt for fungicides, such as Benomyl or Captan, but you MUST use them as directed on the label.

If you don’t want to use harsh chemicals, you can dust your plant with sulfur or baking soda solution. You can make your baking soda solution by mixing one teaspoon of baking soda with a quart of water.

Pythium Root Rot

Pythium Root Rot is another fungal disease that is caused by inadequate soil. The best is to prevent this disease, as in most cases cannot be treated and can be fatal for the plant.

– Causes

Pythium Root Rot is caused by the Phytium fungus. This thrives in wet, unsterilised soil and attacks the roots and the crown of the African Violets. The crown usually turns light gray and the stems begin to rot.

– Symptoms

Obviously, this disease starts from the roots, as its name says as well.

The spores of the fungus attack the roots and then goes up to the crown and stems.

Unfortunately, when the roots are rotting, we can see the damage only when the disease is already well spread.

The stems will wilt and turn mushy, while the leaves may turn healthy. This is why the Pythium Root Rot is so dangerous for your African Violets.

When the disease is going more further, the leaves and crown begin to become pale and the leaves will drop.

– Treatment and Prevention

Unfortunately, Pythium Root Rot is also a fatal disease. Especially because this can be observed late when the leaves are getting sick as well. At this point, it is definitely too late for the plant.

You should throw your plant away and its soil as well.

However, if somehow, you observe the disease in time, while it is still only on the roots, you might still have a little chance to save the plant. Or at least you can try to save it.

First, isolate the plant, and repot it in a fresh, sterilized potting mix. Don’t forget to sterilize the tools, your hands and the pot as well.

Before replacing the plant with the new soil, remove all the diseased parts and dust the remaining parts with sulfur. This could stop the spread of the fungus.

Before repotting, you can also treat the soil with Benomyl, which is a fungicide, just to make sure it stops any fungal spread.

Avoid overwatering and you should not fertilize either until the plant gets bigger.

Pythium Root Rot can be easily prevented by paying attention to its needs, like moist soil, air circulation and clean tools and hands.

Rhizoctonia Crown Rot

Rhizoctonia Crown Rot is another fungal disease that can appear on African Violets and will thrive in wet conditions.

– Causes

Rhizoctonia Crown Rot is caused by the Rhizoctonia fungus. Usually, this fungus, enters the plants when propagated or repotted, through wounds and cuttings.

It is usually infecting healthy plants when contaminated tools, containers or potting mediums are used when you are repotting the plants.

Aso, if one plant is contaminated already, and you don’t isolate it from the healthy plants, then this fungal disease can spread on the other African Violets as well.

– Symptoms

As its name says, Rhizoctonia Crown Rot’s symptom is that the crown starts to rot.

The end of the leaf and flower stems will start to blacken, these will fall off and then the plants will collapse and die.

A reddish infected tissue may also appear at the soil line.

– Treatment and Prevention

Unfortunately, Rhizoctonia Crown Rot has no treatment as it spreads rapidly and is a very invasive disease that kills the plant quickly.

The best prevention is to use clean tools and hands when handling the African Violet. The pot and the potting mix should also be sterilized.

Do not reuse the soil from the diseased plants.

Ring Spot

Ring Spot, in another name Water Spot, is the most common African Violet disease.

– Causes

Ring Spot is caused by the temperature difference between the leaf and the water that touches it.

If cold or hot water is touching the leaves, this will injure the leaf by destroying the ultrastructural composition of leaf cells.

However, if the leaf is warmed up from the sun, for example, the water can still cause injuries even if that is not cold but has room temperature. The idea is that the difference between the leaf temperature and water temperature is too big.

– Symptoms

Bright yellow, or sometimes bleached ring spots, lines or arcs will appear on the leaves, where the water was touching it.

– Treatment and Prevention

Ring Spots are irreversible, but at least these will not spread. Remove the damaged leaves and then discontinue watering your plant from the top.

Instead, water it from the bottom with room temperature water, and avoid splashing the leaves with cold or hot water.

Wrap Up

I hope that your African Violets will not get any of these diseases, but if they do, you can save them.

As I said many times above, the best treatment, for all diseases, is prevention.

Watering your African Violet from the bottom, with room temperature water, and handling them with clean hands and tools, is essential to reduce the chance of any infection.

Keeping them in a spot where they get enough sunlight and the airflow is good and keeping their soil moist at all times, should be enough for African Violets to remain happy.

Updated: September 28, 2021

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