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Box Blight

Cylindrocladium buxicola

Box Blight

by Pauline1. All rights reserved

Box blight is a fungal disease which arose in the UK and New Zealand in 2002. It targets the new stems of plants causing severe defoliation of Box plants. There are two types, each responding differently to various fungicides. The main symptoms of both variants are black streaks on new stems followed by defoliation.
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Leaves brown and eventually fall off the plant. Early leaf fall results in patchy defoliation. You may also notice black streaks on stems or circular patches of what looks like pink-grey mould beneath the leaves.

Growth factors

- Warmth and humidity can speed up the spread of the fungus.


Dark brown spots on leaves.
Pink circles of fungus under leaves in wet conditions.
Black streaks on new stems.
Distinct patches of defoliation.

Biological treatment

This disease spreads incredibly quickly. Sometimes it's best to bin or destroy plants or plantings that are severely affected. Prune out branches if they're large or sentimental to the garden. Pick up any fallen leaves and dispose of them in the landfill. Help plants recover with supplementing them with some fertiliser.


If you've purchased Box from a garden centre, keep it isolated for a few days before planting. If you can, take cuttings of the healthy box in the garden and replant them, as opposed to buying more. Warm, humid conditions quicken the spread of the disease, so be extra vigilant during periods of warm weather. Making hedges convex in shape will help keep plants dry. Only prune in dry weather, and keep pruning at a minimum if possible. Using mulch will help reduce splashing during rain. Keeping good plant and tool hygiene.

Affected plants


Buxus spp.

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