According to officials with the Alabama Forestry Commission (AFC), the existence of laurel wilt disease has now been positively identified in Greene County. After “wilting” sassafras trees were recognized by agency personnel along Highway 43 in the southern portion of the county, stem samples were collected from one of these symptomatic trees and sent to the USDA Forest Service laboratory for verification, where results confirmed the presence of laurel wilt fungus (Raffaelea lauricola). This confirmation makes the third county in Alabama, where the disease was detected in Marengo and Mobile counties in 2011.
In North America, trees in the laurel (Lauraceae) family are susceptible to laurel wilt. Redbay and swampbay are the most common host species of the disease, but sassafras is being attacked more frequently. Other laurel species such as avocado, pondspice, pondberry, spicebush, and camphor are also potential hosts.
The only known causal agent of laurel wilt disease is the redbay ambrosia beetle (Xyleborus glabratus), imported from Southeast Asia. It has continued to spread into new territories by natural progression and the movement of infested fire wood. Since its initial detection in Georgia in 2002, the disease has spread into five other southeastern states – South Carolina, North Carolina, Florida, Mississippi, and Alabama (see map).
Approximately 1/16-inch-long and dark brown to black, the redbay ambrosia beetle bores into a host tree and infects it with the deadly laurel wilt fungus. Leaves on the affected tree eventually turn olive-grey to reddish-brown. In most cases, the symptom of wilting leaves first appears on a single branch, but soon afterwards will be present throughout the entire crown. At times, small round entrance holes are noticeable on the stems from which toothpick-like tubes of compacted sawdust may protrude. The affected tree eventually dies within 4 to 12 weeks after the initial attack.
Controlling this disease can be quite difficult. Salvaging infested trees and chipping the wood into small one-inch pieces can impede the spread. Burning the wood or covering it with a tarpaulin can also stop the movement of redbay ambrosia beetles. Another useful action is halting the transport of infested wood long distances to prevent new introductions of this disease into unaffected areas.
If wilting leaves are identified on redbay or sassafras trees, please contact your local Alabama Forestry Commission office. At this time, early detection is the best method for documenting and potentially stopping the spread of this disease. For more information on laurel wilt, redbay ambrosia beetles, and other non-native invasive pests, visit www.dontmovefirewood.org.
The mission of the Alabama Forestry Commission is to protect and sustain Alabama’s forest resources using professionally applied stewardship principals and education, ensuring that the state’s forests contribute to abundant timber and wildlife, clean air and water, and a healthy economy. To learn more about the AFC or locate county offices, please visit the agency’s website at www.forestry.alabama.gov.