March 15, 2012
Cylindrocladium buxicola (also known as C. pseudonaviculatum), commonly called box blight or boxwood leaf drop is a fungus that has been reported to occur on all Buxus species and cultivars.

C. buxicola has been a serious pest of boxwood in the U.K., Europe and New Zealand since the mid-1990s. The first detections in the U.S. were made in Connecticut in October 2011. Since then it has been found in eight states, including North Carolina, Connecticut, Virginia, Rhode Island, Maryland, Massachusetts, Oregon and New York.

A tour of nursery delegates from Germany, arranged by CNLA, resulted in the Canadian nursery industry put on alert for Cylindrocladium buxicola. Back in October 2011, CNLA made arrangements for the group from Germany to tour nurseries in B.C. and Ontario. The last stop the group made was a visit and lunch at Sheridan Nurseries. The group’s organizer, Dr. Heinrich Losing, a noted extension specialist based in Hamburg noted the importance of boxwood as an ornamental crop all across Canada, and particularly at Sheridan Nurseries. Dr. Losing informed Sheridan about the disease. His advice to Sheridan was simple, “If C. buxicola has not yet been found in Canada, do what you can to ban imports of lining out stock from Europe.”  
Within two to three weeks, CNLA began receiving emails and telephone calls about a new pest of boxwood that had been found in the U.S. CNLA requested CFIA consider regulatory action.

On Jan. 6, the first evidence that the disease had found its way to Canada was confirmed with a positive find of Cylindrocladium buxicola at a B.C. nursery. The grower quickly removed and destroyed all boxwood plants at his nursery as a precautionary measure.

C. buxicola is not a regulated pest, but in view of the popularity and economic importance of this ornamental crop, it is considered a disease of great concern. CNLA is working with growers across Canada to establish Best Management Practices for the control of this disease through the Clean Plants program.

All growers are advised to be very aware of their sources of incoming boxwood shipments. Growers should also be aware that certain varieties such as Buxus sempervirens ‘Suffruiticosa’ (English boxwood) and B. sempervirens (American boxwood) appear to be highly susceptible. However, even those species that do not appear to be susceptible can carry the fungus and it is now believed that asymptomatic plants have been responsible for some of the spread of C. buxicola throughout nurseries and into garden centres and the landscape.

CFIA said that further surveys would be conducted to determine the possible spread of the disease throughout Canada. As of late Feb., no reports have been received. For more information, go to