So sad to see that a large redbay (Persea borbonia) in the mesic hammock at the Oslo Riverfront Conservation Area (ORCA) has succumbed to laurel wilt. Laurel wilt (Raffaelea lauricola) is an invasive fungal disease that arrived in the U.S. at the Port of Savannah, Georgia, sometime before 2002 and in Indian River County in 2006. This disease swiftly attacks the vascular system of plants in the laurel family, Lauraceae.
In 2022 laurel wilt was found in avocado (Persea americana) groves in Miami. A hallmark of this disease is the bronzed leaves that can remain on the tree for many months.
University of Florida researchers are working to ascertain what insects transmit laurel wilt to avocados. The invasive insect, redbay ambrosia beetle (Xyleborus glabratus), is the insect that vectors (transmits) laurel wilt in eastern forests.
Redbay is the only plant presently attacked at the Oslo Riverfront Conservation Area (ORCA). Other “victims” in the laurel family include swampbay (Persea palustris), silkbay (Persea humilis), pondspice (Litsea aestivalis), and pondberry (Lindera melissifolia).
When crushed, redbay leaves emit a spicy fragrance akin to that of the bay leaf (Laurel nobilis) of commerce. This character can help to confirm ID.
The presence of distinctive leaf galls also can help with ID. The redbay psyllid (Trioza magnoliae) lays its eggs undertone epidermis of the leaves, and feeding nymphs cause the leaf edges to curl. Nearly all redbay trees have these galls
Only a few scattered redbay trees remain in Indian River County, though they once were a reasonably common canopy tree in coastal areas. They can grow to be more than 50′ tall. If you have the space in your yard, consider planting a redbay tree to replace what has been lost with the hope that “new” trees will be resistant to laurel wilt. An estimated 300,000 relays have succumbed to laurel wilt.