Cylandrocladium pseudonaviculatum or C. buxicola
Boxwood blight is a serious fungal infection of all plants in the genus Buxus. It is also known to infect Pachysandra. Although research is ongoing, we do know what it looks like and how it infects plants. During warm humid weather, spores of the Cylandrocladium fungus germinate on the moist leaves and stems of Boxwood. Wounds are not necessary for the fungus to enter the tissue. Brown spots with dark edges appear on the leaves, as well as blights, black cankers on stems and subsequent rapid defoliation and dieback. The disease life cycle can be completed within one week during optimum weather conditions.
Boxwood blight is not spread through airborne spores like other fungal infections. Spores are held together in sticky masses and are transferred to other plants by direct contact, use of infected tools, splashing and wind-driven rain. Fungicides are being studied that will limit the spread of the disease, but so far there is no cure. Sanitation is paramount to limit spread of boxwood blight. Disinfect tools between plants during maintenance practices, such as shearing. Remove and destroy infected plants, fallen leaves and stems. Inoculum can survive in leaf litter for at least 10 years and cause new infections.
Currently, experts recommend not introducing new boxwood to historical or significant gardens until more study is done.
Research has shown that Buxus sempervirens ‘Suffruticosa’, Dwarf English Boxwood, is extremely susceptible to this blight. We have begun to limit stock of this type of boxwood. If ‘Suffruticosa’ is needed for a project we will ship it in, but require that customers take receipt of the entire shipment upon arrival.
We are taking all prudent steps to identify, contain and destroy infected plants that are found in the nursery, and will keep our customers up to date with new research as it becomes available.
Further information about Boxwood Blight can be found at http://www.boxwoodblight.org and University extension sites.
Check out our Pinterest board for photos of Boxwood Blight, and other fungal infections and pests that affect Boxwood: http://www.pinterest.com/surfhydrangea/boxwood-blight-and-other-pestsdiseases-of-boxwood/