Camellia diseases: our best tips on identification, treatments & prevention

Camellia japonica is a real eye-catcher in the garden, but equally susceptible to many a pest. Let us show you how to recognise camellia diseases.

The camellia (Camellia) is a relatively hardy potted plant. If it does droop its leaves or flowers, or show other signs of suffering, it is usually because something has gone wrong with its care. We will tell you how to avoid such mistakes and what pests and diseases pose a threat to the camellia.

Camellias: animal pests

We have listed which pests can make life miserable for your camellias, along with tips for effective control.

Thrips (Thysanoptera)

Also known as fringed aphids, thrips are tiny pests that are sometimes barely visible to the naked eye. They prefer to attack houseplants, so they become a problem for camellia in winter. The damage usually manifests itself in silvery, brown to black lesions on buds, leaves and green shoots caused by the thrips’ egg-laying and excretions.

For control: The control of thrips is relatively simple. In some cases, spraying the plant with soapy water is enough to scare away the thrips. If the infestation is not too severe, you can simply wait out the problem. After all, the thrips often cannot cope with outdoor conditions, so when the camellia is put out again, the infestation will take care of itself.

Caution: Thrips, while easy to control, can persist in the soil in pupal form. Under certain circumstances, this can lead to large populations that could cause major problems later on. Especially in commercial cultivation, thrips infestation is more often a problem.

Scale insects (Coccoidea)

These small, relatively flat-looking aphids belong to the family of phloem-sucking insects and damage your camellia by puncturing their proboscis organ. Just like thrips, they are mainly a problem on houseplants and potted plants. Scale insects prefer the softer undersides of leaves to suck on the sugary plant sap. A sure sign of scale insect infestation is sticky honeydew.

For control: For scale insects, it is more effective to prevent an infestation by taking the appropriate measures than to react to it later. So, keep your camellia in healthy condition and provide optimum care. In the event of light infestation, the small pests can still be managed, but in case of heavier infestation it is rarely possible. Should a heavy infestation occur, there are both biological and conventional pesticides on the market to provide relief.

Black vine weevil (Otiorhynchus)

The weevil damages camellias in two ways: firstly, the adult beetles attack leaves by feeding on the leaf margins, and secondly, their larvae often settle in the shallow soil of the containers and damage the roots there. So, if you see leaf feeding, it is highly likely that the soil in the pot is also infested with black vine weevil larvae.

For control: Normally, weevils cause only damage that your camellia can compensate for well in a healthy state. However, if yellow leaves and drooping shoots appear, you can think about plant protection treatment.

Note: Carry out the treatment in the dark, or in low light conditions, as the black vine weevil avoids light.

Camellia diseases: fungal pathogens

A fungal pathogen can also harm your camellias.

Camellia plague (Sclerotinia camelliae)

Camellia plague was previously only common in Asia. For a short time now, it has also been wreaking havoc in Europe. Infestation by the harmful fungus manifests itself in the flowers, which begin to rot from the inside out. The most effective way to cope with camellia plague is to remove the affected flowers. This is sufficient because the fungus only spreads via airborne spores and not systematically within the plant. Camellia plague is so far the only fungal disease that has been shown to affect the camellia. It has many synonyms, including the names ‘camellia blossom blight’, ‘camellia blossom rot’ and ‘tree blight’.

Yellow and brown camellia leaves: what’s wrong?

From time to time, your camellia may not be at its best. Often it is not disease that troubles these beautiful plants, but external abiotic conditions. Let us clarify the possible causes.

Bud drop/leaf drop

Drooping buds and leaves is mainly due to fluctuations in water supply and in large temperature differences in a short time. The camellia is unable to adapt to the constantly changing conditions, resulting in deficiency or excess reactions. Very frequent moves can also be a reason for the fact that external conditions are constantly changing. Usually, however, it is maintenance errors or fluctuating weather conditions that tend to affect the plants.

Rot appearances in the camellia

Just as bud and leaf drop can be a manifestation of improper care, so can rot. Excessive humidity, waterlogging and corresponding temperatures create perfect conditions for rotting. In addition, over fertilisation can cause the tissue to lose its resistance, making the plant more vulnerable.

By and large, the camellia loses its leaves after two to three years, so sporadic leaf fall is no cause for concern. If the symptoms accumulate and no obvious reasons are apparent, it is advisable to first adjust care measures before immediately concluding on a disease.

In order for your camellia to be as robust and disease resistant as possible, you should fertilise the plant regularly. You can learn more about fertilising camellias in our dedicated article.