March 21, 2006

Phil Harmon, UF IFAS Plant Pathology Department
Carrie Harmon, SPDN, UF IFAS Plant Pathology Department

Phytophthora ramorum causes ramorum blight of Camellia and other ornamentals and sudden oak death of tan oaks and California live oaks (different tree than southern live oak). The pathogen is regulated, and recent efforts (past two years) have aimed to limit movement of the pathogen and to destroy plants found to be infected through nursery and environ surveys.

Florida FDACS-DPI has released news that ramorum-positive Camellia plants (23 total) were found in two Florida nurseries on 5 different species of Camellia (japonica, sasquana, sinensis, hiemalis, and vernalis). Both nurseries, Tallahassee Nurseries and Esposito Garden Center in Tallahassee, also were found to be positive in surveys 2 years ago after an introduction of positive plants from California. It is not clear if the pathogen was re-introduced or if it has survived at these nurseries in soil and/or water since those initial finds.

Positive plants and exposed adjacent host plants (2570 total) have been destroyed and both nurseries are now open for business. These findings will likely spawn additional trace-back and -forward surveys in Florida and possibly elsewhere in the Southeast. The positive plants were confirmed by FDACS-DPI, UF/IFAS Extension Plant Disease Clinic, and USDA laboratories through isolations and diagnostic PCR protocols.

What does this mean? The sudden oak death pathogen, P. ramorum, hasn’t faded away and shouldn’t be forgotten. This disease is a major regulatory headache for ornamental nurseries. Results of research and surveys are showing us that even though ideal conditions for the pathogen are cool and wet, it can survive a range of environmental conditions (including hot dry summers) and can accumulate in water and soil. Nurserymen should be careful when obtaining plants known to be ramorum hosts (especially camellias) and should be familiar with ramorum blight symptoms.

Symptoms of sudden oak death and ramorum blight are discussed in the UF EDIS fact sheet titled “Sudden Oak Death” (http://edis.ifas.ufl.edu/PP118). A link to the current USDA host list and additional information is available at http://spdn.ifas.ufl.edu.

If property owners suspect they may have the SOD pathogen on known host plants, they can visit the DPI Web site http://www.doacs.state.fl.us/pi for photos and more information. To submit samples, please contact your county extension office or call the DPI toll-free helpline 888-397-1517.

ATTN: INDIANA RESIDENTS

View the P&PDL Sudden Oak Death web page

Pictorial Guide for Identification of Sudden Oak Death (pdf file) - includes sample submission criteria for Indiana - Purdue University