box blight

Fungicides And Good Gardening Practices Are Ways To Beat Box Blight

One of my services is fungicide treatments for the disease called box blight. The fungal disease attacks Box (Buxus sempervirens) and can result in large, twiggy bare patches and dieback.

Box blight was first recognised in the mid 1990’s and has now become a real problem in many gardens all over the UK, especially with the warm and damp weather.

If you suspect box blight in your garden then please feel free to contact me for advice or to discuss our fungicide treatments to help prevent the disease.

So what is Box Blight?

Box blight is a fungal disease that largely affects Buxus sempervirens (Box) and its cultivars.

Two fungi are the common cause- Cylindrocladium buxicola (syn. Calonectria pseudonaviculata) and Pseudonectria buxi. Identification is best in wet conditions. White spore masses on the underside of infected leaves signifies C. buxicola, whereas P. buxi spores are pink. Both can exist on the plant at the same time but C. buxicola will be the one causing the most damage.

What should I look out for?

Autumn and Winter is usually the time when you may see the first signs of  box blight.

The common symptom is dark brown or black spots appearing on the Box leaves. These will merge to cover the entire upper leaf surface and soon after the leaves will fall off, leaving twiggy, bare patches on the Box.

Look closer and you may see black streaks on the stems. This is caused by the C. buxicola fungus and will cause die-back on the Box plants.

What can I do?

Box blight is not a death sentence for your plants.

If possible, cut out any severely affected areas. As far as is practicable clear any fallen leaf litter and dead material. Destroy both, ideally by burning. Do not put any Box leaf litter, cuttings or dead material  in your compost as the fungus spores can remain viable for at least 6 years. Fungus can also remain in soil so best to remove and replace the topsoil around the affected plants.

Make sure the Box plant is as strong and healthy as possible to improve recovery and increase infection resistance. Do this by mulching annually in Spring with a good depth of quality mushroom compost or leaf mould to help improve the nutrient balance in the soil. Spray the Box plants with a liquid seaweed or Topbuxus every six weeks during the growing season to promote healthy growth.

Increase air movement through the Box plants by reducing the amount of times the box are trimmed. Regular clipping encourages denser growth, which is an ideal environment for the fungus to flourish. If your box is in a border or flower bed, best to reduce overcrowding and improve air movement by removing any other plants growing in close proximity.

Avoid overhead watering as spores can be spread in the water droplets and damp leaves create conditions that the box blight fungus thrives in.

Keep shears, clippers and hedge trimmers clean when trimming infected box to avoid spreading the box blight to healthy plants. Do this by dipping tools in a weak mix of bleach every so often when working, or apply to the blades using a trigger sprayer. One small capful of bleach to five litres of water works well.

Treat the Box plants in Spring and Autumn with a commercial grade fungicide. Applications must be delivered by fully qualified operatives who are certificated by NPTC (National Proficiency Tests Council).

Following this advice does not guarantee success at curing box blight but will certainly improve the chances of the Buxus (box) battling the fungal disease. Remember to continue with the fungicide treatments and good gardening practices even when your Box plants start to recover, to ensure the box blight does not return.

Take a look at the two photos from a garden where I currently work. The first photo was taken in early Spring and shows box hedging badly affected by box blight. The second photo was taken a year later in early Summer, after treatment with fungicides. The Box plants have recovered really well and although there are still a few signs of box blight, the hedge is looking stronger, healthier and with lots of encouraging new growth.



Please contact me if you are concerned about box blight in your garden or would like to know more about my fungicide treatments to combat the disease.

Be Ready for the Box Tree Moth in 2018

Reports of box tree caterpillar damage were on the increase in 2017, mostly in the South East of England and London

Thankfully the risk is still very small where I’m living in the Cotswolds. But I feel it is just a matter of time before for the box tree moths start to travel West.

The Box tree moth (Cydalima perspectalis) is native to East Asia and became established in the UK in 2011. Stoke Poges in Buckinghamshire has the unfortunate label of being the location of the invasion after a local took a caterpillar to the 2011 Chelsea Flower Show to be identified.

Now the main areas of infestation are London and Essex, but it’s realistic to expect the problem to spread to other areas of the UK soon.

The caterpillar of the moth causes the damage by feeding on the leaves of the Box. Defoliation can be very rapid. They can also attack the bark of the box, causing the plant to dry out and die.

Always be alert for the caterpillars, which are characterised by black stripes with white dots on a light green body with hairs and a shiny head. Other signs to look out for are green balls of ‘Frass’ (waste excreta) and trails of sticky webbing. Remove the caterpillars as soon as you see them to prevent damage. With early detection Box tree moth can be controlled.


The caterpillars can be controlled by spraying with an insecticide. You will need to spray hard to penetrate the protective webbing.  The moth’s eggs are also protected by web ‘cocoons’ that stick the box leaves together and offer an good defence against spraying. Personally I try not to recommend using insecticides, except in extreme cases. Their use can have a devastating effect on the beneficial pollinating insects. Best to use an insecticide in the evening when the risk to pollinating insects is at its lowest.


Another solution is Box Tree Moth pheromone traps. They attract and trap the male box tree moth. With no male moths to procreate with the females then the life cycle is broken and no new caterpillars are created to cause the damage.


The pheromone used in the trap will only attract box tree moths so other butterflies and moths should not be affected. And it does not harm beneficial pollinating insects. The main downside is the unpleasant job of regularly cleaning the traps to avoid putrefaction. But this only needs to be done during mid-March and the end of October when the box tree moth is active.

A treatment for box tree moth is Xentari, which is a biological product that is sprayed on to the box to stop caterpillar damage and is safe to use around pollinating insects. This product is now available to buy on Amazon.

In France they are trialling a tiny parasitic wasps. Millions are being released in eastern France with the hope they can kill the box tree moth eggs.

trichogramma wasp

Happy for you to contact me if you are concerned about the threat of the box tree caterpillar to your topiary and box hedging.

Image Credits: Box tree moth damage Box tree moth