Research

Box blights

Box blights are fungal diseases, and are among the more conspicuous problems to affect Buxus sempervirens and its cultivars in the British Isles. At present, two different box blights have been reported. Volutella blight, named after the asexual spore state of Pseudonectria rousseliana, overwinters on fallen leaves, to release spores in spring. These may infect box plants through pruning or other wounds. More recently reported from the UK is Cylindrocladium blight, possibly introduced on plants from mainland Europe.

How box blight affects the garden

Both blights cause the leaves to turn brown and fall, often spreading to affect and kill off whole branches - very damaging to topiary box bushes. Especially in wet weather, patches of spore-bearing fungus, pinkish in Volutella, greyish in Cylindrocladium, may appear on the undersides of the leaves.

Control recommendations

At present, no fungicides are approved for either of the box blights. Control must therefore be a matter of hygiene. All affected leaves and branches, together with any fallen leaves, should be removed and destroyed as soon as the disease is noticed. Inspect plants in nurseries thoroughly before buying.

Box blights were covered in an issue of The Garden:

RHS Wisley Staff. 1998. Problem Profiles: box blights. The Garden (RHS) 123(9): 672-673.

Current work on box blights at Wisley

This topic is part of an active research program in the Plant Pathology section at RHS Garden Wisley. For more information on the box blight investigation click here.

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