Laurel Wilt Disease:  A New Threat to State Park Forests

In January of 2005, park rangers noticed a number of dead and dying red bay trees at Hunting Island. With each passing week, more red bays turned brown and died. It soon became apparent something was drastically wrong. After contacting the South Carolina Forestry Commission it was discovered a new “disease” was attacking and killing red bays in coastal South Carolina.

About Laurel Wilt Disease 
The disease, now known as Laurel Wilt Disease, attacks and kills plants in the Laurel family. The disease is a fungus originally from Asia. It is spread by an Asian ambrosia beetle (Xyleborus glaboratus), first found in the United States in Port Wentworth, Ga. near Savannah in 2002.

By 2003, large numbers of dying red bay trees were found on Hilton Head Island, SC. Since that time, it has spread throughout a large portion of coastal South Carolina, Georgia and Florida. To date, infected trees have been found at Hunting Island, Edisto Beach, Lake Warren and Rivers Bridge State Parks.

Expanding Environmental Threat
Since its initial attack on red bays, Laurel Wilt Disease has also killed sassafras trees in the wild. In laboratory tests, it has also been found to be fatal to other members of the Laurel family, including the federally endangered Southern spice bush (Lindera melissifolia) and the avocado, an important agricultural crop in south Florida. It is now clear the disease presents a clear environmental threat.

Besides the effect on the plants themselves and the Southern forests, several insects depend on the red bay as a food source at some point during their lifecycle, including the spicebush, Schaus and palamedes swallowtail butterflies. In fact, the palamedes swallowtail is completely dependant upon the red bay for its existence as its eggs are laid on the leaves and the emerging caterpillars only eat red bay leaves.

Field Laboratory Experiments
Several researchers are using state parks as field laboratories. Three studies are approaching the problem from different angles to help find solutions. One study is focusing on the beetles themselves. By increasing our knowledge about the beetle and its lifecycle, it may be possible to find seasonal weaknesses that can be used against the beetle. Another study focuses on monitoring the changes within the forest as the red bay continues to decline from the coastal forests. Still, a third study is looking for resistance within the red bay populations to the disease. This may in turn allow the species to repopulate and the forests to recover naturally.

How You Can Help
Although there is currently no cure for the disease, park visitors can help by doing their part to slow the spread of the disease. Do not take or remove firewood from a park infected by Laurel Wilt Disease. Conversely, do not bring infected wood onto a state park. A further step is to resist the urge to cut down dying red bays. By cutting infected trees you infect your chainsaw and thus can spread the disease the next time you use your saw in a different location. Your help is greatly appreciated.