Officials with the Alabama Forestry Commission are concerned but not surprised by the news that laurel wilt disease has now been found in two counties in Alabama. The U.S. Department of Agriculture (USDA) and Iowa State University laboratories confirmed that tree stem samples collected in Marengo and Mobile counties were positive for the fungus, Raffaelea lauricola.
This non-native invasive insect-disease complex primarily affects trees in the laurel family, with redbay, swampbay, camphor, and sassafras being especially susceptible. Other potential hosts in the laurel species include pondberry, pondspice, spicebush, and avocado. A host tree becomes infected with the disease when a redbay ambrosia beetle transmits the fungus into the walls of the sapwood. Quite virulent, the fungus then clogs the vascular system of the tree, preventing the flow of water. As a result, black streaks appear in the sapwood. Soon, the entire crown presents wilted reddish-brown foliage and within weeks, the tree will succumb to the disease.
Laurel wilt disease was introduced into the United States in 2002 on untreated wood packing material from Asia, first attacking redbay and sassafras trees in Georgia, then spreading into South Carolina, Florida, Mississippi, and most recently North Carolina. When two redbay ambrosia beetles were captured in traps near Grand Bay, Alabama back in October of 2010, the disease was predicted to spread into Mobile County within the next few years.
One probable cause for spread of the disease is the long-distance movement of untreated wood products. Infested firewood, wood chips, and even yard debris can become possible carriers of the redbay ambrosia beetle. Avoiding the movement of infested wood and proper disposal can dramatically reduce the threat.
Unfortunately, very little success has been achieved in containing redbay ambrosia beetle and the associated laurel wilt disease through current control methods. There are, however, some actions that can be implemented to reduce and possibly prevent the further spread of this devastating exotic pest. Any host tree confirmed of having laurel wilt disease should immediately be salvaged. If possible, burn the wood debris of the affected tree on the site, of course, following all state and local regulations. If burning is not an option, at least leave the cut tree at that location. Do not haul cut wood debris killed by laurel wilt disease to other sites. Always buy “local” firewood if travelling to another destination for recreational activities.
For additional information on the redbay ambrosia beetle and laurel wilt disease, please visit:
www.forestry.alabama.gov – Insect, Disease & Invasive Species – Insects – Insect Advisory;
www.fs.fed.us/r8/foresthealth/laurelwilt/index.shtml; or www.aces.edu/ucf/RedbayWiltStory.php. The Alabama Forestry Commission is a state agency committed to protecting Alabama citizens and the state’s invaluable forest assets.