Conditions of wet weather and high humidity have been very favorable for boxwood blight in the Mid-Atlantic region, where states have confirmed boxwood with the serious blight. The fungus Calonectria pseudonaviculata causes severe defoliation and death of container boxwoods, and dieback of in-ground plantings.
Most boxwood species are susceptible, including American and English boxwood (Buxus sempervirens), little leaf boxwood (B. microphylla) and hybrids such as B. sinica. Pachysandra is a host, and can be a source of spores causing new infections. Sweetbox (Sarcococca) has been identified as a host. Other diseases affect boxwood, and environmental stress plays a role in predisposition to disease. 
Timely and accurate identification by microscopy is important for management of this aggressive disease. Sanitation is extremely important in management. Contact DE Dept of Ag or the UD Plant Diagnostic Clinic if you suspect boxwood blight.
NFG 9/28/2018
