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Common Begonia Problems (Diseases and Pests)

Common Begonia Problems (Diseases and Pests)

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Begonia plants are beautiful and commonly used as houseplants and plants to decorate a garden. However, these plants can have their share of problems, which can begin to affect their overall health. So, what are the common issues that you will probably face with your Begonias?

There are several common problems that you could face with your Begonia plants. Most of the problems are disease or pest-related, but they can drastically affect your plant’s health, with some diseases like leaf spot requiring you to destroy the infected plant as there is no cure.

Begonias can be used as indoor and outdoor plants, but wherever you keep them, they are prone to a few problems. Let’s see how to identify what your plant may be infected with and how to treat it if you can.

Common Problems with Begonia Plants

When you have planted your stunning Begonia plant, and you have been lovingly and tentatively caring for it and supplying it with its every need, only to one day see that the plant is beginning to look worse for wear.

Alternatively, you may be researching what problems a Begonia plant may have as you are trying to decide if you should buy one for yourself or not. Either way, seeing a Begonia go through some health issues is discouraging for Begonia plant lovers.

If you own one of these plants already and are putting a lot of effort into your plant every day, only to have the plant start declining in health and not being as happy as you expected it to be can bring you down.

Unfortunately, several things can impact the health of Begonia plants, which can make it somewhat difficult to find the issue and fix it.

Here are the problems you may face with a Begonia plant:

  • Various Diseases develop on the plant like leaf spot and others
  • Various pests attacking your Begonia plant like the greenhouse whitefly

Many of the problems caused by these diseases and pests can cause the Begonia plant to have stunted growth. Some can lead to the death of the Begonia plant if the problem is not fixed immediately after you have seen it.

Let’s go through these problems in detail and go over each of the diseases and pests you might face to see how you might fight them to save your Begonia and possibly avoid these pests and diseases in the future.


Unfortunately, Begonia plants are prone to several diseases that can affect their health in varying ways. Some of these diseases are easier to cure than others, but you need to act quickly with all of them if you wish to try and save the plant.

Let’s go through the most common disease you might face with your Begonia plant to ensure you are ready to treat it if it develops or to possibly even avoid it in the first place.

Leaf Spot

The Leaf Spot

Leaf spot is a disease that frequently affects Begonias. This is an infectious disease that can spread from plant to plant and cause many problems in your garden. The first signs that you are dealing with leaf spot are the sudden appearance of dark spots on the leaves, otherwise known as water-soaked leaves.

As this disease progresses, the spots will spread to all the plant’s leaves and the surrounding Begonias around the infected plant. This disease will eventually kill the affected plants.

There is no cure for this disease; all you can do is try to prevent the spread of leaf spot to the surrounding plants by removing and destroying the infected Begonia. Ensure you thoroughly clean your garden tools and don’t overhead water your Begonias to try and avoid this disease.


Blight On Begonia

Blight is very similar to leaf spot in appearance on Begonia plants. This disease will also present with dark spots or water-soaked leaves, and it’s very common in Begonias. Blight will also spread from plant to plant and cause all plants infected with it to die very slowly.

There is also no cure for blight, apart from removing and destroying the infected plants. You should also try to clean up any dropped leaves from the infected plants and destroy those as well.

If you leave these dropped leaves, the disease can make its way into the soil and become an even bigger problem for you. You can help prevent this disease by not overhead watering your Begonias and thoroughly cleaning your garden tools.

Foliar Nematode

This disease is another nasty one that is, unfortunately, quite common with Begonia plants. Foliar Nematode is a disease that will stunt the Begonia plant’s growth, causing it to be a lot smaller than it should be.

This disease will present with excessive amounts of red pigment developing in the Begonia plant. Then the plant leaves will become water-soaked or develop bronzed patches on them.

What is frightening about this particular disease is that a plant can be heavily infected and show little to no indicators until it’s too late. If your Begonia is infected, you need to remove it and destroy it before spreading it to other plants.

Powdery Mildew

Powdery Mildew On Begonia Plant

Powdery Mildew is a fungal infection that develops of the leaves, stems, and flowers of various plants, including Begonias. The tissues of the plant underneath the fungus could begin to die if the fungus is not treated, and it can eventually kill your Begonia plant.

You should examine your Begonia carefully and regularly, as early detection of this disease will increase your chances of saving your plant.

You can treat this Powdery Mildew with a fungicide, and you can easily prevent it by maintaining a fungicide schedule with your Begonia plants. You need to ensure you buy a fungicide made for Begonias as these plants can be sensitive to certain chemicals.

Pythium Rot

This is another fundus that will kill your Begonias if you are not aware of the infection in your plants. This fungus will present itself as shiny blackened areas that will develop on the petioles and stems of your Begonia plants.

This fungus can easily spread from plant to plant and needs to be treated as soon as you notice it. If your Begonia is established in your garden, it will be affected right at and slightly above the soil line of your Begonia. This can cause your plant to start collapsing at those locations and eventually die.

If you find this fungus on your plant, you can treat it with a fungicide. You can help prevent this fungus from developing by not overwatering your Begonia, keeping the ends of your garden hose off the ground, and planting your Begonias in pasteurized soil.

Rhizoctonia Crown Rot

This disease is similar to pythium rot, and it is also a fungus that will grow on your plants if you aren’t careful with your plant’s care. This fungus will also affect the stems of the Begonia plants at the soil line and cause them to rot.

This will lead to your Begonia collapsing in this area and subsequently dying. With Rhizoctonia crown rot, though, you will also notice a fine and delicate webbing of fungal growth appear between infected plant stems and between the stems and soil particles close by.

You can treat Rhizoctonia Crown Rot with a fungicide and then help prevent it by keeping to a fungicide treatment schedule with your plant and planting your Begonias in pasteurized soils.


Some Begonias can also be infected by certain viruses that can cause the death of the plant and can spread to surrounding plants, causing a big problem in your garden. Many different viruses can affect Begonias, but they mostly present with the same symptoms.

You need to look out for the following symptoms that indicate a viral infection in your Begonia plants:

  • Malformed leaves
  • Mosaic leaves
  • Pale yellow ring spots on the leaves
  • Stunted growth
  • Chlorotic mottling of the leaves

If your Begonia shows any of these symptoms, they are most likely suffering from a viral infection. When you notice a viral infection in your plant, you need to discard the infected plant before the infection spreads.

You can try and help prevent viral infections in your plants by planting them in pasteurized soils, maintaining good control of thrips and aphids, and not introducing infected plants into your garden.

Pests on Begonia Plants

Diseases are not the only things common to Begonias, which can cause problems with your plants. Begonias are prone to attack by certain pests, and they can begin to do some serious harm to your plants if untreated.

When you spot any sign of a pest infestation on your Begonias, you need to treat it as soon as possible to avoid the death of your plant. Let’s look at the common pests that Begonias are prone to and how to get rid of them.

The Greenhouse Whitefly

The Greenhouse Whitefly Can Happen On Begonia Plants

The Greenhouse Whitefly is an annoying little pest that will generally infest your Begonia if there is an increase in the humidity surrounding your plant. These pests will bite into your plant and suck out its juices.

This will cause the leaves to discolor at the site of the bite, and the plant will gradually dry out due to dehydration. If this infestation is not treated in time, it will eventually kill your Begonia plant.

When you see an infestation of Greenhouse Whiteflies occurring on your plant, you can treat it with a soapy water spray.

You can make your own soapy water spray by diluting 1.3 oz (40ml) of liquid soap in 33 oz (10 liters) of water. Before spraying this on your plant, you need to cover the root system to avoid damaging it.

Red Spider Mites

Spider Mites Are Possible On Begonia Plants

Red Spider Mites are another very common pest that infests Begonia plants. You will most likely first notice these pests by their tell-tale “spider web”- like structure they create on the plants they are infesting.

At the beginning of the infestation, the leaves of your Begonia will begin to marble. The leaves will then soon be covered in the webbing of this pest, and the leaves will then turn yellow and fall off the plant.

Red spider mites will usually be found on the back of the plant’s leaves and will be attracted to your Begonia due to abundant irrigation and very warm weather conditions. You can treat this pest with a soapy water spray and prevent it with a neem oil spray.



Greenhouse Thrips are fairly large pests that you should easily see on your Begonias. These pests will lead to the discoloration of your plant’s leaves and slow down or completely stop your plant’s growth.

These pests love humid conditions and high temperatures, meaning they will multiply if these conditions are met. This could cause the infestations to become uncontrollable. To help get rid of this pest, you can use a soap water spray, and then to help avoid it in the future, you can use a neem oil spray.

Greenhouse Aphids


Greenhouse aphids will bite into your Begonia plants and feed on their sap. If this pest’s population grows out of control, these pests can kill your Begonia plants.

A common sign that your Begonias are infested with these aphids is if the plant’s leaves are turning yellow and are beginning to twist out of shape and then fall off.

These pests can cause your plant to become dehydrated, which can cause your plant to droop. To treat these aphids, you need to use insecticides as they breed fast, so you need to get the situation under control quickly.

You need to use an insecticide specifically made for Begonias as they are sensitive to certain chemicals. You should be able to buy one at your local garden supplies store.

Final Thoughts

Begonia plants are stunning plants with beautiful flowers, making them a favorite among many gardeners. However, these plants can have some problems that affect their health.

If you are concerned about the health of your Begonia plant, you can go through the list of common problems that these plants face and try to figure out what is wrong with your plant. Good luck with your Begonia plant!

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