Box Blight is a fungal disease of boxwoods caused by two fungi: Cylindrocladium buxicola and Volutella buxi – it’s not uncommon for them to act in concert. It is found across Europe and beyond and first arrived in the UK in the mid 1990s.
The bad news is that it is spreading and there is no proven cure. The better news is that it is still relatively uncommon and there are steps you can take to minimise the chance of infection….
Dispersal and Infection
The spores are dispersed in water, including wind-blown rain. Animals (including humans) and birds may also spread them – wind alone is unlikely to disperse them far.
Volutella buxi will only infect a plant whose leaves and/or stems have open cuts, making them particularly vulnerable after pruning (please see below). Cylindrocladium buxicola, however, can infect undamaged plants and is more serious.
The first signs of Box Blight are dark or light brown spots or lesions on the leaves. The affected leaves will themselves then turn a straw or brown colour before falling off. The stems also develop dark brown or black lesions.
In the wet, the spores may be seen on the underside of infected leaves – pink for Volutella buxi and white for Cylindrocladium buxicola.
• Never water overhead – always water at the base
• Never cut or prune boxwood when it is a) raining, b) the plant is wet or c) it is humid
• If you have established Box in your garden, always ‘quarantine’ new Box plants for at least a month before planting near established plants
• Only buy Box from a reputable nursery like, of course, ourselves