Both American and English boxwood are susceptible to this disease caused by the fungus, Pseudonectria rouselliana. The imperfect stage is Volutella buxi. Before new growth appears in the spring, leaves on the tips of infected branches turn red, then bronze and finally yellow. Infected branches die back. Examination of affected branches reveals loose bark and girdling at varying distances from the tips and discoloration of the wood. In moist weather the fungus produces salmon pink fruiting bodies on leaves and stems.
Management: Diseased branches should be pruned out and when the foliage is dry, plants should be thinned to improve air circulation and light penetration. Old fallen leaves and diseased leaves that have accumulated in the crotches of branches in the interior of the plant should be shaken out and removed. Properly timed applications of copper fungicides or lime sulfur applications can be used in severe infections. Sprays will not cure diseased branches. Spray applications should start just before new growth begins in the spring and continue until new growth is completed. Additional sprays may be needed in the fall to protect late summer growth during rainy seasons. Adequate spray coverage is essential for disease control and thick foliage will prevent spray penetration which will reduce the effectiveness of disease control.