Boxwood blight, a serious disease that can kill infected plants within a season, has now been confirmed in North Carolina, Virginia and Connecticut (Middlesex, Fairfield, Hartford and New London counties so far).
The disease, discovered in the mid 1990's, is present across Europe and in New Zealand, and it is not known how the pathogen entered the United States. The blight, also called box blight and boxwood leaf drop, is caused by the fungus Cylindrocladium buxicola, also known as C. pseudonaviculatum, and it can spread rapidly in warm and wet conditions.
English boxwood (Buxus sempervirens 'Suffruiticosa') and American or common boxwood (B. sempervirens) are particularly susceptible to the fungus, but the fungus has also been found on the popular Korean boxwoods (Buxus sinica var. insularis, formerly known as B. microphylla var. koreana), little leaf boxwood (B. microphylla), and Japanese boxwood (B. microphylla var. japonica). The fungus also affects sweetbox (Sarcococca spp).
I was very disturbed to find that the fungus attacks some of the most popular boxwood hybrids, including 'Winter Gem', 'Green Velvet', 'Graham Blandy', 'Green Mountain' and many others.
To prevent the fungus from spreading, scientists recommend that homeowners increase spacing between boxwood plants to maximize air circulation, avoid overhead watering and remove any leaf debris. If you notice symptoms like dark or light brown spots on leaves, leaves that turn the color of straw, or defoliation, report it immediately to your local extension office.
For more information, see the Connecticut Agricultural Experiment Station website here, or Saunders Brothers Nursery in Virginia, a major grower and developer of some of the most popular new boxwood hybrids.
(photos: CT Ag Experiment Station)
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