Box Blight detected in the United States
Ag officials across the country are reacting to the detection of Cylindrocladium buxicola, a blight afflicting boxwood shrubs, at U.S. nurseries.
The U.S. Department of Agriculture detected the pathogen in multiple Eastern states and Canada last fall. To date, it appears the disease has had limited impact in Oregon: Officials have inspected twenty Oregon nurseries and found just positive detections. Both nurseries are expending significant resources and working closely with the Oregon Department of Agriculture to eradicate the pathogen on the growing grounds.
Officials believe the fungus came over on infected plant material from Europe, where it is considered widespread. They’re advising growers to keep an eye out for symptoms, and to avoid conditions that promote fungal growth. Please see the cultural management and disease control guide documents below for detailed information and photos.
On June 29, 2012, an established bed of pachysandra was found infected by Cylindrocladium pseudonaviculatum, according to Connecticut officials.
The blight can cause rapid defoliation. Symptoms include dark or light brown spots on leaves, black streaks or cankers on stems, and bronze- or straw-hued discoloration on foliage. The disease spreads quickly in warm and humid conditions, and in shady areas -- the environment often found in boxwood production.
The OAN is strongly urging growers to be aware of the disease and particularly cautious regarding any boxwood plant imports from outside the state. While evidence to date suggests the disease is limited in Oregon, officials and the OAN are taking it seriously and have encouraged members to have their plant material tested, primarily to assure themselves and their customers.
Following are reports that include details and images of this disease.
Cultural Management of Boxwood Blight
Oregon State University Extension Plant Disease Control Guide
North Carolina State University report
Virginia Tech report
Connecticut Agricultural Experiment Station
North Carolina State University (2-hour webinar)
Boxwood Blight on Pachysandra (pictures)
The OAN is in close communication with ODA on the matter and will keep members informed as more news and resources become available.
Members can contact the ODA plant division directly with specific questions: 503-986-4640. For the full contact list at ODA, visit www.oregon.gov/ODA/PLANT/NURSERY/contact_us.shtml. John Griesbach of Ascent Agricultural Services may also be contacted for consultancy on this issue: 503-508-7030 / firstname.lastname@example.org.