Boxwood Blight on the Move in the U.S.

February 07, 2019

GCA Clubs Share Best Management Practices

Member clubs of the The Garden Club of America (GCA) are taking action to educate their members and local communities about boxwood blight—a devastating fungal disease that is on the move in the United States. Caused by Calonectria pseudonaviculata, the blight was first reported in the United Kingdom in the mid 1990s. It is now widespread in Europe and has emerged in New Zealand. In October of 2011, the blight was found in North America in both North Carolina and Connecticut and is now reported to be in more than 22 states and at least 3 Canadian provinces. Importing shipments of infected boxwood from surrounding states has proven to be a problem. In May 2018 boxwood blight arrived in Indiana through a shipment to home and garden stores—on the move again. Learn about the resources GCA clubs are sharing with their members and communities about the best management practices. 

The following websites offer more information about best management practices relating to this serious threat to garden landscapes.

The Virginia Extension Service

Purdue Extension Plant and Diagnostic Laboratory

The fungus can infect all above ground portions of the shrub and the first symptoms are dark leaf spots that progress to twig blight and rapid defoliation and eventually death of the plant. Narrow black streaks (cankers) that appear on the green stems are often visible. In high humidity conditions, white, fuzzy masses that are clumps of spores will emerge from the black stem cankers and the underside of leaf spots. The spores are the true bugs. They move through water splashes, pruning tools, wheelbarrows, and anything that may have contacted infected plants. They have also been found living in cut boxwood greenery used for holiday decoration.  

Boxwood blight is also resistant to treatment. The best control once the infection begins is to remove the diseased plant AND all the leaf debris. Boxwood blight has great survival skills and will live in the soil for 5 to 6 years—replanting the same cultivar is not generally advised. Pachysandra terminalis, Pachysandra procumbens and Sarcococca species are also susceptible to this disease as they are in the same family as boxwood.  When faced with boxwood blight, the homeowner should avoid using leaf blowers or mobile equipment around the plants in order to limit the spread of the disease.   

It is especially important to clean up and dispose of any diseased plant material. Do not compost.   

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