Contact: Kenneth Billings
STARKVILLE, Miss.--A team of Mississippi State entomologists is confirming the arrival on the Gulf Coast of an insect threat that could cause extinction of an entire tree species.
About half the size of a grain of rice, the Redbay Ambrosia beetle (Xyleborus glabratus Eichhoff) discovered recently in Jackson County is a native to Asia. The near-microscopic insect carries the pathogen for the devastating laurel wilt disease that kills the host plant in a matter of weeks--and for which scientists have yet to find a defense.
"Potentially, this could remove a historic component of our coastal plain forest, and in the longterm, redbay trees could cease to exist," observed university entomologist John Riggins.
Redbay, a native evergreen found commonly in coastal forest and urban plantings, sometimes is used in cabinet-making and woodturning because of its attractive grain.
Riggins said an investigation was launched after a concerned landowner contacted the local MSU Extension Service office. The landowner was seeking help in determining the cause of numerous tree deaths on his property.
Arriving on the coast, MSU researchers discovered more dead and dying trees in the Mississippi Sandhill Crane National Wildlife Refuge, which is located between U.S. Interstate 10 and Highway 90 in the state's most southeastern county. They hung traps to capture the pest and collected wood chips so the fungal pathogen could be identified positively.
In addition to redbays, the disease affects all varieties of laurel trees, including swamp bays, sassafras, avocado, poundspice, pondberry, and camphor--some of which are common in certain areas of the state. The tree becomes infected with the laurel wilt pathogen when the beetle bores into the bark.
Riggins said the insect first appeared in the U.S. in Georgia in 2002, then spread along the Atlantic coastal plain in Georgia, Eastern Florida and South Carolina. Prior to the recent discovery, no beetles or infected trees had been found in areas neighboring Mississippi.
"There is a large gap between the previously confirmed populations and what we've discovered here," he said. "There are several hundred miles between the two populations, so it is very important for us to figure out how it got here so we can plan how best to combat further spreading."
Riggins said the insect could have been brought to the Gulf Coast area through camper-transported firewood or in packing materials of shipping containers arriving from Asia, among other means.
Riggins said controlling spread of the disease and insect should be considered a top priority, though control and management options are limited. Sanitation cuts attempted in Georgia to combat spread of the infestation proved largely unsuccessful, he added.
He said coast residents are being urged to contact a local MSU extension agent so testing may be conducted to confirm the insects' presence. Symptoms to watch for include:
--Wilting or reddening of redbay or sassafras foliage; or
--Small, toothpick-like structures studding the surface of tree trunks that are composed of sawdust extruded by boring beetles.
"Advanced stages of mortality exhibit dead, reddish-bronze foliage that hangs on the tree for up to a year," Riggins said. "Scraping away the outer bark will reveal a characteristic dark black fungal streaking underneath."
To help slow the spread of both beetle and disease, coast residents are being asked to not transport cut redbay wood, since it could be infested and spread the disease to unaffected areas of the state.
NEWS EDITORS/DIRECTORS: For additional information, contact Dr. Riggins at 662-325-2984 or jriggins@entomology.msstate.edu.
For more information about Mississippi State University, see http://www.msstate.edu/.