Cylindrocladium buxicola (syn. C. pseudonaviculatum), a
fungal disease of boxwood commonly known as boxwood blight, is not native to
the US. The pathogen was most likely transported to the US on boxwood from
nurseries in Europe.
- First known find in Pacific Northwest: At a nursery in Washington
County, Oregon in December 2011.
- Found in the eastern US: At nurseries in Surry County, North
Carolina and Carroll County, Virginia, and at a residential landscape in
Middlesex County, Connecticut in October 2011.
All boxwood species may be susceptible to blight, however
American boxwood varieties appear to be particularly vulnerable. The boxwood
family Buxaceae and a member of this family, Sarcococca, have been shown to be
susceptible to the fungus C. buxicola.
- Light or dark brown circular leaf spotting
- Black longitudinal or diamond shaped lesions on stems
- Results in defoliation of leaves and an overall straw
colored appearance of the plant
Disease transmission is increased in moist environments,
making host plants in greenhouses particularly susceptible. The fungus can form
resting structures (chlamydospores and microsclerotia) that can survive for
years on host organic debris in the soil. Mortality most often occurs in
seedlings, but may also take place in older plants, especially if infected with
a secondary pathogen.
Boxwood blight has been reported throughout Europe, the United Kingdom, and New Zealand. In the US, 16 states have reported boxwood blight: Alabama, Connecticut, Delaware, Georgia, Kentucky, Maryland, Massachussets, New Jersey, New York, North Carolina, Ohio, Oregon, Pennsylvania, Rhode Island, Tennessee, and Virginia. In Canada, it has been found in British Columbia, Ontario, and Quebec.
Nursery Cleanliness Program for Boxwood Blight
This voluntary program of inspections and best management
procedures is designed to help a nursery provide clean boxwood nursery stock to
their customers with more confidence. Please see the Nursery Cleanliness
Program document for more information on how to enroll.
Boxwood blight fact sheet
Symptoms, transmission, and geographic distribution Document
Boxwood Blight Nursery Cleanliness Program