Laurel wilt – a possible threat to Everglades restoration

Published June 19, 2013
A survey of laurel wilt damage to swampbays in an Everglades tree island.

A survey of laurel wilt damage to swampbays in an Everglades tree island.

Florida’s redbay trees are dying at an alarming rate, at the hands of a dangerous pair – the deadly combination of a symbiotic plant pest and disease called laurel wilt.

First discovered in 2005 in Duval County, laurel wilt disease has since spread south and is covering a vast section of Tamiami Trail, potentially threatening the Everglades. The disease, caused by a fungus transmitted by the invasive redbay ambrosia beetle, kills avocado and other trees in the laurel family. The insects can enter Florida on infested firewood and host trees; for that reason, it is recommended to use local firewood only.

Jacksonville District is part of the Everglades Cooperative Invasive Species Management Area (ECISMA), a formal partnership of federal, state and local government agencies, Tribes and interested groups. Everglades restoration poses new challenges for invasive species management and a need for cooperation among agencies and organizations at higher levels of policy and management.

Recent survey flights by ECISMA confirmed laurel wilt is expanding rapidly across the Everglades. The primary method of control for laurel wilt, proposed by the Florida Department of Agriculture and Consumer Services, is scouting and early detection, leading to suppression of redbay ambrosia beetle. Educating the public – gardeners, homeowners and landscapers – about the signs of laurel wilt and redbay ambrosia beetles is a top priority.

“Our concern is that it will open up niches for invasive species to thrive; they out-compete our natives,” said Jon Lane, chief of the Invasive Species Management Branch.

The implications are huge, because a loss of tree island ecosystems would result in a loss of the valuable services they provide for wildlife. Tree islands are considered an extremely important contributor to habitat heterogeneity and overall species diversity within the Everglades ecosystem because they provide nesting habitat and refuge for birds and upland species and serve as hotspots of plant species diversity within the Greater Everglades, according to a U.S. Fish and Wildlife Service report.

 “I am concerned about laurel wilt causing bay tree mortality on tree islands; this mortality would leave gaps within the canopy that would allow other invasive species to colonize, further degrading the system by reducing native tree species diversity and causing cascading effects to other ecosystem component,” said Gina Ralph, chief of the South Florida Section of the Planning Division’s Environmental Branch.