Box blight
A fungal disease that causes boxwood leaves to develop dark spots, turn brown and fall, leaving bare stems with black streaks.
Also known as: Boxwood blight, Calonectria pseudonaviculata
Symptoms and identification
Dark brown leaf spots, rapid leaf browning and leaf drop, and black streaks on young stems. White fungal growth may appear under leaves in humid weather.
Causes
Spores spread in rain splash, on tools, clothing and infected plants, and need warm, humid conditions.
Organic treatment
Remove and bin infected plants and all fallen leaves; do not compost them. Feed and water healthy plants to help them regrow.
Prevention
Buy healthy plants, disinfect shears between plants, avoid clipping in wet weather, and improve airflow. Consider resistant alternatives such as Japanese holly.
Chemical treatment (use with care)
Use a fungicide labelled for box blight as a protectant during humid weather.