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PLNA e-News: Plants, Pests & Diseases

PDA Issues Boxwood Blight Quarantine

Wednesday, June 29, 2016   (0 Comments)
Posted by: Gregg Robertson
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On June 25, 2016, PDA imposed a quarantine on areas where boxwood blight is found. This quarantine could affect nurseries, garden centers, rewholesalers and landscape contractors harboring affected plants. In addition to land area, the quarantine covers equipment, tools and other vectors for the spread of the disease. Click here for a copy of the quarantine order.

The Pennsylvania Department of Agriculture has declared boxwood blight to be a "regulated pest." The goal of regulating this disease is to stop its artificial spread by human activities, particularly the propagation and distribution of boxwood and other host plants.

The quarantine order:

  • Allows for the quarantine of any property, facility, premise, place or area where boxwood blight is confirmed.
  • Restricts movement of any material or object that may carry or spread the fungus. This restriction applies to both inter- and intrastate movement.
  • Requires proper inspection of any material that would enter the commonwealth from another state. That state must certify that the shipper meets commonwealth standards before its plants are allowed to enter Pennsylvania for resale distribution.
  • Requires businesses within the commonwealth that can meet the requirements of the quarantine order to enter into compliance agreements with the department for clean stock production.


In 2011, boxwood plants in the U.S. were found suffering from a new disease, Calonectria pseudonaviculata, boxwood blight. This disease is caused by the fungal species Calonectria, and can result in complete leaf loss and blight of the plant. Other names by which the fungus may be referenced are Cylindrocladium buxicola or C. pseudonaviulate


The disease cannot be identified from visual symptoms due to the fact that similar symptoms can be the result of other issues. It is necessary to have a laboratory confirm the presence of the fungus to diagnose boxwood blight.  Spores of the fungus can be spread by insects, birds, pets and horticultural tools. The fungus can survive in leaf litter for years; control measures for the disease include destruction of the infected material, and blending chemical treatments with cultural practices.


What to Do


If you suspect you may have symptomatic boxwood plants, please contact your local Penn State Cooperative Extension County office. Replanting with boxwood, pacysandra or sarcocca is not recommended, if the previous plants had Boxwood Blight. Even if diseased material is removed and the area cleaned, there are not guarantees the fungus is removed. It is recommended to substitute other plant material.


Homeowners and landscape contractors should sanitize tools, equipment and gloves when working with boxwood. A 10% bleach solution or other appropriate sanitizing solution to clean tools and equipment should be applied between pruning boxwood and after completing all pruning and cleaning. Removal and proper disposal of leaf debris will help limit the spread of the spores which carry the disease.  Clothing should be thoroughly washed.


Nurseries and those handling boxwoods should implement the best management practices recommended by AmericanHort. Landscape contractors, garden centers and rewholesalers should purchase boxwoods only from those nurseries who have implemented these best management practices.


Do Not Compost Blighted Boxwoods


Boxwood, pachysandra and sarcococca should not be composted if removed due to Boxwood Blight. Spores live for years and will not be destroyed during composting.


For More Information on Boxwood Blight:

AmericanHort Knowledge Center
Connecticut Agricultural Experiment Station Fact Sheet

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