PPDL Picture of the Week for
March 19, 2012

What do Pachysandra and Boxwood Have in Common?

Pachysandra is part of the Boxwood Family and both Pachysandra and Boxwood are susceptible to Cylindrocladium pseudonaviculatum, the fungus that causes Boxwood Blight.

Boxwood blight, a fungal disease that was identified for the first time in the United States in 2011, has been confirmed on boxwood plants in OH, NC, CT, VA, MD, PA, NY, RI, MA, OR and British Columbia, Canada. Recently, plant pathologists at the Connecticut Agricultural Experiment Station found that the fungus which causes boxwood blight can also cause disease on Pachysandra ground cover, which is also known as Japanese spurge (Pachysandra terminalis). Healthy pachysandra plants were inoculated with spores of C. pseudonaviculatum and lesions developed on the leaves ten days after inoculation. Three weeks after inoculation, many of the leaves with lesions yellowed and dropped. Heavy sporulation of the fungus was observed. This raises significant concerns about pachysandra as a potential source of inoculum for infection of boxwood and vice versa. The leaf spot and dieback symptoms may be confused with a common and widespread disease of Pachysandra, known as Volutella blight. See more detailed information about Volutella Leaf Blight on Pachysandra.

Boxwood blight has not yet been confirmed in Indiana. The branch dieback we commonly observe on boxwood is caused by a number of factors including Phytophthora root rot, Volutella leaf and twig blight and abiotic (non-infectious) decline related to site stress factors stemming from extremes in moisture and temperature.

Keep a watchful eye on all NEW PLANTINGS  of boxwoods and on older boxwoods in planting beds where new boxwoods were recently introduced.   Please contact us if you see symptoms of this newly introduced fungal disease amidst any NEW installations of boxwood.

 

For more information:

Boxwood Blight New Host: Pachysandra - The Connecticut Agricutural Experiment Station

A New Boxwood Blight in the US - What's Hot, November 30, 2011

A Boxwood Blight New to the US, Cylindrocladium pseudonaviculatum (pdf file) - NPDN Pest Alert

The 'box blight' pathogen: Cylindrocladium pseudonaviculatum (pdf file) - USDA-APHIS-PPQ-CPHST and NCSU-Department of Plant Pathology

Boxwood Blight - A New Disease for Connecticut and the U.S. (pdf file) - The Connecticut Agricultural Experiment Station

A new pest to the U.S. Ornamental Industry: The 'box blight' pathogen (pdf file) - NC Pest Alert

Boxwood blight confirmed in Ohio - Nursery Management, March 28, 2012

Boxwood blight found on pachysandra in Connecticut landscape - Nursery Management, July 6, 2012

 

Click image to enlarge

Pachysandra with leaf lesions (J. A. LaMondia).

Sporulation on lower leaf surface (J. A. LaMondia).

Leaf spots caused by Cylindrocladium buxicola on Buxus sp., Ct. Dept. of Ag

Stem lesions caused by Cylindrocladium buxicola on Buxus sp.; M. Munster, NCSU, Dept. of Plant Pathology

 

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service