What is box blight, and what should replace box hedging?

Box blight is a fungal disease causing leaf drop and dieback in box, and it arrived alongside a second problem — box tree moth, whose caterpillars strip foliage entirely. Between them they have made box hedging a considerably riskier choice than it was.

Recognising box blight. Dark leaf spots, black streaks on young stems, rapid leaf fall leaving bare patches, and in humid conditions a white bloom of spores on leaf undersides. It spreads in wet, still, humid conditions and by water splash — which is why it moves fastest in dense clipped hedges where air does not circulate.

Recognising box tree moth. Green and black caterpillars with white webbing through the plant, and rapid, comprehensive defoliation. The webbing is the distinguishing sign, and the damage is faster than blight.

Managing box, if you want to keep it:

Clip in dry weather, and disinfect tools between plants.

Clear fallen leaves from the base, where spores persist.

Water at the base, never over the foliage.

Improve air circulation, and avoid very dense formal clipping in humid sites.

Do not clip in humid conditions, since fresh cuts are entry points.

Pheromone traps for the moth indicate when to act, and biological control is available.

Accept that heavily infected plants are usually best removed, with soil and debris disposed of rather than composted.

The alternatives, which now perform better in most gardens:

Ilex crenata — small-leaved holly, the closest visual match, and it needs acid to neutral soil.

Euonymus japonicus compact cultivars, tolerant and fast.

Lonicera nitida, cheap, fast and requiring more frequent clipping.

Taxus baccata — yew, the best long-term formal hedge by a distance: dense, tolerant of hard pruning, long-lived, and slower than its reputation suggests only in the first years.

Pittosporum tenuifolium, in milder areas.

Osmanthus and berberis, both reliable.

The broader lesson: monocultures of a single clipped species across a whole garden concentrate risk, and mixing species is the practical defence against whatever arrives next.