January 16, 2012
C. buxicola positive find in Canada
Cylindrocladium buxicola (also known as C. pseudonaviculatum) and commonly known as 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 UK, Europe and New Zealand since the mid 1990s. The first detections in the US were made in Connecticut in October 2011. Since then it has been found in eight US states, including North Carolina, Connecticut, Virginia, Rhode Island, Maryland, Massachusetts, Oregon and New York.

On Jan. 6, the Canadian Food Inspection Agency confirmed a positive find of Cylindrocladium buxicola at a B.C. nursery. The original source of infection has not yet been confirmed. Further surveys will be conducted by CFIA to determine the possible spread of this disease throughout the rest of Canada.

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

As an immediate precautionary measure, 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.
The following links provide more information on C. buxicola.
Boxwood Blight – A New Disease (Journal of Plant Pathology)
Study on Control of C. buxicola using Fungicides and Host Resistance

Boxwood growers are especially encouraged to download and view the webinar that was hosted on Jan. 5 by North Carolina University Extension Services.  Boxwood Blight Webinar with Kelly Ivors, Associate Professor and Extension Specialist Department of Plant Pathology, NC State University