Boxwood Gardening at Home

This aggressive disease is more of a threat to boxwood performance in the landscape than any other disease of boxwood because it may destroy all the shoots and leaves of an infected plant. It can easily be confused with the more-familiar Volutella blight of boxwood, but boxwood blight strikes much more quickly and affects healthy rather than stressed or injured boxwood. Initial symptoms of boxwood blight appear on leaves as black, cloudy spots that lack a distinct edge; spots often enlarge to encompass the entire leaf, and then the leaf usually drops from the plant. Catastrophic leaf drop is often seen after a period of wet weather. Leaf spots vary from dark brown to black. There may also be tiny black cankers on young shoots, but these are usually black streaks rather than girdling cankers. Leaf blight is often seen across the tops of hedges but may also be seen on the top or sides of individual boxwood specimens. Whitish masses of spores appear on the underside of blighted leaves or on infected stems, and these are easily mistaken for Volutella blight, for which spores are white to pink. To further confuse the viewer, other fungi may sporulate on leaves killed by boxwood blight. Boxwood blight affects large areas of leaves quickly, whereas Volutella Blight most often foliage is killed on a single stem, slowly, following a wounding event such as snowload breakage.