In the previous few years, boxwoods have been repeatedly damaged by an unknown source. Raj Singh, a plant pathologist from LSU AgCenter, noticed this and identified the cause as the fungus Colletotrichum. It causes random die-back of twigs and a black discoloration of the stem. There are currently no official recommendations for treatment for the fungus. Considering this, take extra care to sanitize your pruning equipment to prevent the spread of the disease to healthy plants. If you suspect your boxwoods have been infected, please contact your AgCenter extension. Removal of infected plant matter may help prevent the spread of this new pathogen.
Landscape Disease Control