Cylindrocladium busicola (syn. C.pseudonavicalatum ) aka Box Blight
Boxwood Blight is a new disease for the United States that effects all boxwood species. It has recently been identified in Virginia. It survives for years in plant debris and in soil even after the plant dies and decomposes.

Symptoms (which are similar to Volutella blight and root rot diseases) include leaf spots and blights, rapid defoliation, distinctive blank cankers on stems, and severe dieback.

It spreads via air currents and activated by water radiply in warm, humid weather. The boxwood flight fungus readily forms fruiting structures, sporadochia, on the underside of infected plant leaves and on the black lesions on stems visible with a hand lens. Boxwoods in close proximity to each other are highly susceptible.