Aucuba Japonica Diseases (What You Need to Know)

The hardiness of Aucuba and its ability to grow in dry, shaded areas make it a good choice. Despite its reputation, Aucuba can contract infections as a result of environmental causes. 

So, what are the most common aucuba japonica diseases?

Some of the most common Aucuba Japonica diseases are Aucuba blackening, foliage burn, and nonpathogenic root rot. Aucuba blackening is caused due to excess moisture or fungus. Foliage burn is caused due to excess heat. Whereas, nonpathogenic root rot is caused due to excessive use of fertilizer. 

But there is definitely more to these diseases. In this article, we break it down for you. So if you want to know how it happens and how to deal with it, then keep on reading. 

Let’s dive right in! 

Common Aucuba Diseases 

aucuba japonica diseases

Not knowing about your plant can make it hard for you to identify its diseases. The same goes for Aucuba. Aucuba mostly gets affected by 3 diseases.  

However, they can also be saved from those. We’ve mentioned all of it down below.

Disease 1: Aucuba Blackening 

Are the leaves and the shoot tips of your Aucuba plant developing black moist spots? Then it’s most likely Aucuba blackening or Phytophthora root rot. Azalea, rhododendron, and Aucuba shrubs are typically affected by this soil disease.

Root stress caused by excessive moisture levels in the soil is the most common cause of blackening. This is usually seen during cold, rainy winters.

Other stressors, such as root infections (mostly phytophthora root rots), could also be at play. The fungus can be found in most soils. Unfortunately, there’s no way to get rid of it. 

Preventive Measures 

Once a plant has been harmed with Aucuba blackening, there is no way to save it. So the best thing is to avoid it completely. To do so, follow the below-mentioned guidelines.

Aucuba should not be planted in places that are prone to flooding.

Incorporate bulky organic materials into a larger area before planting. This will improve the texture and drainage of heavy clay soils. You can use composted bark, garden compost, or well-rotted farmyard manure. 

Planting on low, wide mounds approximately 20cm (8in) high in moist areas can help.

Mulching with organic materials that are bulky can also be useful. Mulch should not be applied to the plant’s base. Here are some that you can try –

With the help of these Mulch, you can further protect your Aucuba plant. 

Disease 2: Foliage Burn 

Aucuba Japonica thrives in the shade. Black leaf spots or blotches can appear on plants growing in exposed locations. In early spring, exposed plants are seen to suffer the most.

This happens because of the total decomposition of leaves, petioles, and branches. 

Exposure to direct sunlight mixed with cold damage might result in this condition. Botryosphaeria sp., a weakly pathogenic fungus, is commonly detected in such tissue.

And is common on many woody ornamental plants under stress.

Preventive Measures 

Aucuba Japonica suffers from foliage burn when it is exposed to full sun. To avoid it, you must keep your plant safe from such an environment. Try following the below-mentioned steps. 

Only plant Aucuba japonica in somewhat shaded regions suitable for plants. Like many plants that grow in shade, they thrive the most there. For that, you can use plant shade. Here are some to try. –

These products will provide the much-needed shade that your plant needs. 

During the cold winter months, give vulnerable plants some protection. 

Dead branches should be pruned out several inches below any sign of discoloration as soon as possible. 

Excess fertilizer should be avoided, especially in the late summer and fall.

Disease 3: Nonpathogenic Root Rot

Root rot is a big problem for every plant including Aucuba. Especially when it comes to nonpathogenic root rot. Aucuba japonica may also develop nonpathogenic root rot. 

This happens if it is grown in soil with a lot of organic materials and is poorly drained. 

This disease may also appear if excess fertilizer is applied too close to the plant’s crown. It harms the stems and the roots of the plant. If left unattended, it can damage the neighboring plants as well. 

Preventive Measures 

It is difficult or impossible to eradicate certain bacterial illnesses. So the best option for affected plants is to remove and destroy them. 

To prevent the disease from spreading, the process begins with proper cleanliness. 

Destroy the plants that have been harmed. As well as the soil and garden detritus that has come into touch with them. 

No neighboring plants should be transplanted to other parts of the garden. New plants should be quarantined by being grown in a separate bed from the rest of the garden. Until they have been verified disease-free. 

Aucuba japonica should not be planted where other Aucubas, Azaleas, or Rhododendrons have died. Use separate pots for all of them. Here are few sturdy ones you can try.

Use these plant pots to keep the plants separate from one another. 

These are all the diseases that you should look out for if you own an Aucuba Japonica. If you want your to be healthy, make sure to carry out these preventive measures. 

Frequently Asked Questions

Question: How much light does Aucuba need?

Answer: Aucuba Japonica can grow in practically any soil, with the exception of wet soil. In hot summer climates, use it in full sun to part shade, or in full shade.

Question: Does root rot go away?

Answer: The plant may die if the root rot is left untreated for a long time. Root rot can kill plants in as little as 10 days in extreme circumstances. Root rot is usually fatal, but it can be treated. Affected plants are unlikely to survive, but they can be propagated.

Question: Can I hard prune Aucuba Japonica?

Answer: Yes, you can. But prune during mid-May. Remove all of the prunings, and the plant will most likely bounce back with new growth in about a month.


Now you know all about aucuba japonica disease. Along with what you need to do to avoid them. And if your plant suffers from any of the diseases, you’ll be able to identify it. 

We hope this article helped you understand a bit more about Aucuba Japonica. 

Thank you for being patient and staying with us till the end.

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