An Ophiostoma Species and Xyleborus glabratus Threaten Red Bay and Other Members of the Lauraceae in the Southeastern Us

Stephen W. Fraedrich, Thomas C. Harrington, and Robert J. Rabaglia

USDA Forest Service,Southern Research Station (1) and Forest Health Protection (3) and Iowa State University Department of Plant Pathology (2)

Extensive mortality of red bay (Persea borbonia (L.) Spreng) has been observed in maritime forests of the southeastern United States since 2003. Trees exhibit wilt-like symptoms and a black discoloration of the sapwood.  A fungus has been consistently isolated from the discolored xylem of symptomatic trees throughout the range of the problem.  This fungus has been identified as an Ophiostoma sp. based on sequences of the ribosomal DNA and its tolerance of cycloheximide, and the anamorph of the fungus is similar to the genus of ambrosia beetle symbionts, Raffaelea.  Field and growth chamber studies have determined that the fungus is pathogenic to red bay and causes a vascular wilt. A recently-introduced exotic ambrosia beetle, Xyleborus glabratus (Eichhoff), also has been consistently found in dead and dying red bay trees, and the Ophiostoma species has been isolated from the beetle. The beetle is native to Asia, where it is associated with plant species in the family Lauraceae.

As of February 2006, the disease has been confirmed in ten coastal counties of South Carolina and Georgia.  The disease was also discovered near Jacksonville, Florida in the spring  2005.  Most red bay trees are now dead in areas around Hilton Head Island, South Carolina where the disease has been recognized since 2003.  Dead and dying sassafras Sassafras albidum (Nutt.) Nees) with similar wilt symptoms have also been found in some Georgia counties affected by the wilt of red bay.  The affected sassafras were infested with X. glabratus, and the Ophiostoma sp. was isolated from symptomatic sapwood.  Pathogenicity tests have confirmed that sassafras and other members of the Lauraceae (swamp red bay, P. palustris (Raf.) Sarg. and spicebush, Lindera benzoin (L.) Blume) are susceptible to wilt caused by the Ophiostoma sp.

corresponding author:

Stephen Fraedrich
USDA Forest Service
Southern Research Station
320 Green St.
Athens, GA  30602
706-559-4273
sfraedrich@fs.fed.us