Boxwood Blight: A widespread fungal disease that effects all Boxwood varieties. Therefore it is especially devastating to English and American varieties; Korean varieties show signs of resistance. The sticky fungal spores are dispersed by wind, animals and birds, shoes and loose clothing, garden tools, etc. It is also supported by hosts plants Pachysandra terminalis and Sarcococca species once in a landscape. The primary spread of blight is through introduction of asymptomatic plant material to unaffected areas. Symptoms appear as small brown to black lesions on leaves and twigs, quickly spreading through and from plant to plant and across the landscape, leaves turn straw color and fall off.
There is no post infectious cure, infected plants should be removed from the landscape asap. Fallen infected leaves should be collected ideally by vacuum and all material should be disposed of in a landfill. The spores remain viable on infected leaves and soil for 5 years preventing the use of new Boxwood as replacement plant material. Prevention may be possible by applying fungicide to all leaves and twigs on a consistent schedule. The times of fungal activity (spring and fall) which is difficult considering Boxwoods natural leaf/twig density.
How to take care of a Boxwood shrub to help reduce likelihood of fungal infection include: