Laurel Wilt Worries

Laurel Wilt Worries

The redbay ambrosia beetle transmits a destructive fungus to trees and shrubs which it forages upon.

The redbay ambrosia beetle transmits a destructive fungus to trees and shrubs which it forages upon.

Laurel wilt is a disease affecting redbay (Persea borbonia) which is a facultative wetland shrub or small tree throughout much of its range. This disease is caused by the introduction of a non-native fungus (Raffaelea lauricola) via the invasive ambrosia beetle (Xyleborus glabratus). Laurel wilt compromises the ability of the plant to uptake and transport water, causing leaves to wilt and eventual death of the tree. At this time only plants in the Lauraceae family native to the U.S. southeast are known to be susceptible, with redbay being the primary target. Also affected is sassafras, pondspice and pondberry, but specimens have not been found with the ambrosia beetle on them.

Additional research has shown that avocado plants could be susceptible as well, and this would be the largest economic impact to the agricultural industry. While other native host species may not cause typical commercial damage in the way of wood utilization, fruit production or ornamental trade, the economic, ecological and aesthetic impacts cannot be well quantified. Other impacts associated with laurel wilt on redbay and other laurel species may include; cost to property owners and managers due to removal and disposal of dead or infected trees, diminished property values caused by large-scale removal of dead trees, increased cost and time usage for municipalities to produce and distribute educational materials and to develop and implement management plans, lost revenue for nurseries which deal in affected laurel species and time lost to quarantine protocols and possible fire hazards created by disposal of large amounts of dead woody material.

Laurel wilt interrupts a tree's ability to transport water causing leaves to wilt and eventually death of the plant.

Laurel wilt interrupts a tree’s ability to transport water causing leaves to wilt and eventually death of the plant.

Several management methods are considered and possibly used when instances of laurel wilt are discovered. Limiting transport of infested or infected host material is key when managing for laurel wilt; restricting the transport of firewood, logs, mulch, local disposal of affected plant material and responsible production and sale of nursery products will all assist in stemming the spread of laurel wilt. In many wild areas, redbay and laurel populations are not managed at all, the disease is allowed to run its course. The sanitation management method includes removing affected individuals and diseased populations as well as a surrounding quarantine perimeter. This method is energy intensive and not always successful. An attempt at chemical control in Florida is using macro-infusion of fungicide seems to protect trees from reinfection for 1 to 2 years, but at that point additional intervention is necessary. Trap-out, attract and kill for the redbay ambrosia beetle is being employed in an attempt to stop transmission of the fungus. Of course, integrated pest management, utilizing some or all of these methods in a responsible and efficient manner may be the most effective method in combatting the spread of laurel wilt. For more information about the disease, its impacts and management.