Laurel wilt disease

Natural History
Redbay trees killed by laurel wilt
Photo credit: Dr. Bud Mayfield, FL DOF/DOACS

Laurel wilt disease is caused by the fungus Raffaelea lauricola, which invades the vascular tissue of trees in the laurel family (Lauraceae) and causes rapid wilting and death of affected trees. The fungus is spread by the exotic Redbay Ambrosia Beetle (Xyleborus glabratus), which feeds on the fungus in wilting trees. Laurel wilt is responsible for mass mortality of native redbay (Persea borbonia) trees and threatens avocado production in the state.


 

Identifying Characteristics

Identifying the injury: Affected trees display wilting crowns; foliage often turns reddish-brown and remains attached to dead trees (defoliation occurs on avocado). Blackish-brown vascular discoloration is evident on the sapwood (under the bark) of infected trees. Frass tubes and boring dust (signs of the redbay ambrosia beetle) are usually seen on and near dead/dying trees.
Identifying the insect vector: Although the fungus is not readily visible to the naked eye, the redbay ambrosia beetle, vector of the disease, is commonly seen around affected trees. Beetles are very small – about the size of a small grain of rice and are black in color.
Susceptible trees: Members of the laurel family (Lauraceae) including: redbay, swamp bay, sassafras, spicebush, pondberry, camphor and avocado

 

Images

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