General gardening topics

Buxus problems – Box Blight and other diseases

Last updated on June 8th, 2022

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Most of the issues you face with any plant, including your box plant, have to do with less-than-ideal conditions. It’s important to understand that pests and diseases don’t typically attack a plant unless it is already at a disadvantage. This might mean a plant that’s drying out because of inadequate nutrients or water, which leaves it susceptible to pest infestations, or an inadequate airflow and level of light can leave it susceptible to fungal infections.

That being said, it’s important to provide your box plant with as effective a start as possible by keeping conditions ideal and checking on your plant regularly so that you can stop a problem before it escalates. Nevertheless, it’s important to be able to identify different symptoms that you might encounter with different parts of the plant.

Problems that affect the leaves

  • If you notice that the colour on the leaves has faded entirely and it has burn spots on them they could simply have been scorched by the sun. Excessive sunlight can cause sunscald to your leaves. This is also more common with fresh new growth so pruning later in the year can resolve this issue.
  • If the foliage turns a light bronze colour or has an orange hue (usually right after a hot weather spell) it could be the result of environmental stress. However, this could also be symptomatic of root damage in the winter caused by waterlogging.
  • If the foliage turns yellow it can also be symptomatic of waterlogging, especially if you already know that your garden has heavy clay soil. Look at improving your soil to improve the drainage.
  • During the winter if you notice the margins and the tips of the leaves turning yellow this is simply a result of low temperatures and it will recover come spring.
  • If you have your plant in an exposed area it’s more likely to have leaf discolouration often caused by cold winds. This usually also recovers in spring when new foliage appears.
  • For younger growth, the newer developments in the spring, if there is a late frost in your area the younger growth might turn a pale brown. We only recommend pruning young plants in spring and then pruning around August once they are established. This helps avoid many issues including box blight.

Learning how and when to properly prune box plants helps to avoid many of these problems.

In almost all of these situations, you can apply fertiliser in the spring, and clip away any discoloured areas, and this will go a long way toward rectifying the problem.

Problems that affect the roots

The roots are subject to one particular problem and that is waterlogging. If you notice damaged roots you want to remove them and trim them back after you have replanted your Buxus. You will know if the roots are waterlogged when you remove them from the ground for an examination because you will notice a black or blue colour in the cross-section, with roots that fall apart and simply fall off the plant when you try to tease them. Sometimes this issue is found too late and the plants cannot be saved.

The dreaded box blight (Cylindrocladium buxicola)

The biggest problem you will face, however, is that of box blight. This is one of the most serious issues that Buxus plants are susceptible to. Box blight is a disease that affects the leaves and stems, caused by a fungus. It happens when there isn’t enough air or light circulating through your plant, which is why regular pruning and trimming are so important.

Box blight won’t kill the roots but it is a serious problem that can affect the entire plant and usually, the only thing you can do is destroy affected plants. The leaves will turn brown and then fall off, resulting in large bare patches along the stem. You will see black streaks and dieback, especially on younger stems, and you might even notice white spores of fungus on the underside of the leaves.

You always want to remove any affected areas and dispose of them properly. You should also frequently clip the foliage to provide better ventilation and regularly prune your hedges, but not until later in the season once they are established. If you have less severely attacked box plants you can try to remove affected parts of the plants and spray them with a fungicide. Badly affected plants are best removed. It’s worth mentioning that fungicides can help suppress box blight but, unfortunately, will not control it completely.

Always clean your pruning tools or clippers with disinfectants in between use to help minimise the spread.

Recommended for treating box blight

Volutella blight (Pseudonectria buxi)

Volutella blight results in leaf spots, bare patches and stem dieback on your box plant, just like Buxus blight, but luckily it’s not as bad and can be controlled more easily.

It’s caused by a fungus and can leave characteristic black streaks. Much like other plants, and other conditions, your box plant has to be affected by environmental stress or have a wound that can be infected. You can treat this by removing diseased branches and any fallen leaves on the ground so that the disease doesn’t spread.

Box Rust 

Box rust is caused by another fungus and although it’s not particularly troublesome you’ll notice that it has rusty, blister-like pustules on the leaves, often developing in autumn and winter. The new leaves are affected by the fungus which continues to grow as the infected spots become thicker and bigger. You should clip away any affected areas and treat them with a fungicide. 

Recommended fungicides for box diseases including box blight


No matter the disease that is affecting your box plant, you should always disinfect your tools in between clipping one plant and another. When you clip away the affected leaves or stems from a single plant, always disinfect between times to prevent the accidental spread to another plant. Some people recommend using single-use alcohol wipes for this purpose. This is not something that should happen only when you notice a disease, but something you should do regularly.

Similarly, as mentioned multiple times, it is up to you to make sure that your plants are given the correct growing conditions and that they are not stressed in any way. A stressed plant is a susceptible plant, especially to things like box blight and box rust. The more care you put into maintaining proper environmental conditions, nutritional balance, watering, and pruning and trimming, the more likely you are to reduce an outbreak of these diseases.

Last update on 2024-05-19 / Affiliate links / Images from Amazon Product Advertising API

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