Box hedges and topiary is not a feature of the estate but we do have several box balls planted both directly into the ground and in containers around the garden. Box blight is a disease that we have struggled with for the past three years as evidenced by the disfiguring bald patches on some of the balls.
Horticultural boffins have found two different strains of the disease that often occur together: volutella buxi which causes the browning of leaves with pinkish spores and dieback of branches and cylindrocladium buxicola which causes dark brown spots and grey fungal growth underneath with black steaks on the stems. A sudden patch of yellow leaves at the base of a plant though is more likely to be a dog or cat peeing or marking its territory.
We regularly check our plants and act swiftly if we find affected leaves to cut them out and gather any on the ground with a vacuum, the leaves then being burnt and certainly not put on the compost heap. Our cutting tools are then wiped with white spirits to prevent the spores being spread from plant to plant.
We are dealing with a fungal disease that spreads in wet conditions. Affected container plants can be moved to a dry shed, remembering to water them at soil level. We can avoid using sprinklers on box plants grown in the ground but one can do little about natural rainfall except for building a make-shift shelter if one was zealous enough.
Ventilation is important to prevent stale air accumulating around the leaves. Any neighbouring plants whose foliage touches the box balls is cut back to allow the wind to blow through. Feeding the box balls with a seaweed or comfrey stew-water is vital to build up the strength of the plant to combat the effects of the disease.
Box allowed to grow to its normal unwieldy size does not suffer from box blight and so the disease has come through our insistence in constantly pruning a shrub into unnatural shapes and sizes. Reprieving a box from its annual clipping will allow the shrub to gather its strengths again, ready to be clipped the following year. The experts recommend clipping once a year, traditionally after Derby day in early June to avoid any late frosts and before the end of June to toughen new shoots ready for the first frosts of the autumn.
The very best cure however for this disease is a hot, dry summer and thirty-three degrees is reckoned to be the temperature needed to destroy the spores. One can but pray!