Plant Industry - Plant Protection Section

What is it and what does it look like?

Sudden Oak Death (SOD), ramorum leaf blight and ramorum dieback  are all names for a recently-discovered plant disease caused by the fungus-like microorganism Phytophthora ramorum.   This disease has killed tens of thousands of oak trees in the coastal areas of California and a small area of Oregon.  The host list is broad and continues to expand. It includes common native and ornamental landscape plants like camellia, viburnum, pieris, rhododendron, pyracantha, mountain laurel, and leucothoe. SOD does not usually kill these non-oak hosts.  Instead, depending on the plant, it may cause symptoms such as leaf spots, defoliation, twig and branch dieback, or blighting.   These symptoms can be easily confused with those caused by other plant diseases or environmental stresses. Laboratory analyses are necessary to confirm the presence of SOD in all cases.

Why is it a threat to NC?

Many North Carolina nurseries and nursery dealers buy ornamental plants from other States for resale to homeowners and landscapers. Most of these plants are shipped from States where SOD occurs. The federal plant quarantine intended to prevent the spread of SOD out of infested areas is based on periodic plant inspections and testing. However, for a number of reasons, there is still a chance that infected plants could be shipped to a retail nursery in NC, purchased by a homeowner or landscaper, and then planted in the landscape where SOD could become established. SOD could also spread directly from infected plants in a nursery onto plants in the surrounding natural areas.

SOD has never been found in the landscape or forests of North Carolina. However, based on results of controlled testing, some of our eastern U.S. oak species are highly susceptible to SOD. Its establishment here could cause economic and regulatory problems for the lumber industry, adversely impact our forest ecosystems, and result in aesthetic damage in forested and urban settings. When this disease is detected in nurseries, specific regulatory actions are required to prevent further spread.

What happened in 2004?

In March 2004, the NCDA&CS received notification that thousands of plants possibly infected with SOD were shipped over the previous 12 months from an infested nursery in southern California to more than 1200 locations in 39 states. Sixty-nine of these locations were in North Carolina. This was NC’s first experience with SOD.   NCDA&CS personnel inspected all of these locations, and SOD was eventually found at 9 of them -- but only on plants shipped directly from the infested California nursery. These plants were destroyed. Based on subsequent surveys conducted by NCDA&CS and NC Forest Service personnel, SOD did not spread inside the NC nurseries to other plants or become established in the surrounding areas.

Later on in 2004, NCDA&CS received several more of these “trace-forward” notifications involving other infested nurseries and tens of thousands of plants. Over 90% of these plants had already been sold to homeowners and landscapers in NC by the time the NCDA&CS received the notifications.

In May and June 2004, NCDA&CS personnel surveyed over 100 high-risk nurseries and nursery dealers as part of the USDA-APHIS-PPQ-funded nationwide SOD survey. No SOD was detected at any of these locations.

What happened in 2005?

The NCDA&CS received two additional “trace-forward” notifications from California, but nothing on the scale of those in 2004.  One of these involved shipments of camellias (mail-order) to around a dozen homeowners.  The other involved a small number of plants shipped to 2 NC nursery locations.  NCDA&CS personnel again visited each site and sampled plants but found no evidence of SOD.

In May and June, NCDA&CS again participated in the nationwide SOD nursery survey funded by USDA-APHIS-PPQ.  As an added precaution, almost all of the “trace-forward” sites from 2004 were also re-surveyed.  In all, 120 nurseries and nursery dealers were inspected.   Samples from over 1550 plants were collected and assayed in the lab.   No SOD was found at any location.  The NC Forest Service also conducted surveys in natural and forested areas.  No SOD was found during their surveys. 

What happened in 2006?

The NCDA&CS received two “trace-forward” notifications. One involved 6 retail locations and 154 plants from Oregon. The other involved 80 retail locations and over 11,000 plants from California. All locations were visited by NCDA&CS personnel and any remaining plants were inspected. However, most of the suspect plants had already been sold by the time personnel arrived. Samples from remaining plants with symptoms were sent to the NCDA&CS lab for assay. No evidence of SOD was found at any of the locations.

In mid-April through mid-July, NCDA&CS again participated in the nationwide nursery survey funded by USDA-APHIS-PPQ. A total of 99 nurseries and nursery dealer locations were surveyed for SOD, nine of which were previously-confirmed locations from 2004 re-inspected as a precaution. Around 249 plants samples were submitted to the lab for assay. No evidence of SOD was found at any of the locations.

Current status and plans for 2007

Summary maps show the extent of the survey effort in North Carolina over the past three years. Many of the locations were surveyed more than one time. Based on these and other surveys conducted by the NC Forest Service in forested areas, we do NOT believe SOD is currently established anywhere in North Carolina. NCDA&CS personnel will continue to survey nursery and nursery dealers in 2007.

If you think you bought a SOD-infected plant . . .

Because a large number of “trace-forward” plants have been sold before they could be inspected and sampled, the NCDA&CS established a free testing service to assist homeowners and landscapers who have concerns about SOD. Nursery growers and retailers may also use this service. A series of questions (PDF File) has been developed to help determine if there is a need to submit a sample. A submission form (PDF File) must be completed and sent with the sample. Plants testing positive for SOD must be destroyed to prevent further spread. If SOD has already spread to other plants at the site, these as well as other plants in a designated buffer area may also have to be destroyed.

Plant samples sent to NCDA&CS will be tested for SOD only, not other diseases . For assistance with other ornamental plant problems, contact your local NC Cooperative Extension Service Office . If you have concerns about oaks or other trees, contact your local NC Division of Forest Resources County Ranger .

For More Information:

USDA-APHIS-PPQ (quarantine information, host lists, regulatory protocols, more).  USDA-APHIS-PPQ.

SPDN - Southern Plant Diagnostic Network (current SOD news and information)

COMTF – California Oak Mortality Task Force (in-depth SOD site, picture gallery, more)

PRED - Phytophthora ramorum Educate to Detect (an SOD educational program)

Best Management Practices for Nurseries in California and Oregon (some practices may be used by NC nurseries and nursery dealers to avoid the introduction and establishment of SOD)