Sudden oak death, Phytophthora ramorum, is a funguslike disease that causes leaf spots, cankers, and dieback in more than 12 families of plants. Also known as ramorum leaf blight or ramorum dieback, the disease has been found primarily in California and Oregon. It is of concern to land managers in the eastern United States because at least two eastern oak species, northern pin oak (Quercus palustris) and northern red oak (Quercus rubra), are highly susceptible to the disease.

Sudden Oak Death in Maryland

In March 2004, the California Department of Food and Agriculture confirmed that camellia, viburnum, and lilac samples collected at Monrovia Nursery in Azusa, California, and Specialty Plants, Inc., in San Diego County, California, were infected with Phytophthora ramorum. Plants were shipped from these nurseries to nurseries in 39 states, including Maryland.

On March 29, 2004, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service began regulating the interstate movement of plants that can carry sudden oak death from all California nurseries. California nursery owners must have nursery stock inspected before it can be transported across state lines. This measure prohibits about 1,500 California nurseries from shipping susceptible plants until those nurseries can be inspected and found to be free of the pathogen.

Signs of the Disease

Be aware of the signs of sudden oak death. Some species, including coast live oak, black oak, Shreve oak, and tanoak, sustain lethal trunk infections, while other plants get less serious leaf and twig infections.

Plants with leaf infections play a key role in the spread of sudden oak death because the disease is moved through the air by windblown rain.

Anyone who suspects that the disease is present in a new location should contact the local Extension office for reporting information.

The Maryland Department of Agriculture urges Maryland residents who purchased camellias, viburnums, or lilacs in 2003 or 2004 to call the Maryland Cooperative Extension Home and Garden Information Center at 1-800-342-2507 for information on how to participate in a homeowner survey for sudden oak death in Maryland.

For More Information

Photo of Sudden Oak Death in Maryland

Regulated and associated hosts of sudden oak death are located at the comprehensive SOD site from USDA APHIS

Maryland Invasive Species Council Web

National Ag Pest Information System (NAPIS) P. Ramnus page