Laurel Wilt: Critical Threat to Atlanta's Sassafras Trees

What Is Laurel Wilt?

Laurel wilt is a deadly vascular disease of trees in the laurel family (Lauraceae), caused by the fungus Harringtonia lauricola (formerly Raffaelea lauricola) and spread by the redbay ambrosia beetle (Xyleborus glabratus), an invasive insect originally from Southeast Asia. The beetle bores into the tree and introduces the fungus, which clogs the water-conducting tissue and typically kills the tree within weeks to a few months.

How to Recognize It

• Sudden wilting of leaves in part or all of the canopy, often looking like severe drought stress
• Foliage that turns olive-green, then reddish, then brown, but stays attached to the branches on evergreen species (like redbay) for months
• Premature leaf drop on deciduous hosts such as sassafras
• Dark streaking or staining in the sapwood, visible just under the bark or in a cut branch
• Tiny strings of compacted sawdust (called frass toothpicks) protruding from the bark, signs of the boring beetle
• Rapid branch dieback followed by death of the entire tree, sometimes within a single growing season

The redbay ambrosia beetle is most active during warm months, so new infections and symptom expression are most often noticed from late spring through early fall. Once a tree is infected, however, decline can be rapid at any time of year.

Why It Matters for Atlanta Trees

Laurel wilt is almost always fatal once a tree is infected, and there is no reliable cure for landscape trees. Long-term monitoring plots in Georgia documented mortality of roughly 87% in redbay stands and 80% in sassafras stands, and the disease can spread to nearby laurel-family trees both through beetle movement and through natural root grafts between trees of the same species. In the Atlanta area, sassafras (Sassafras albidum) is the most commonly affected host, with spicebush (Lindera benzoin), a native understory shrub, and occasionally redbay (Persea borbonia) also at risk. Beyond the loss of the tree itself, dead and dying specimens can become a falling hazard near homes, driveways, and walkways.

General Prevention

• Do not move firewood, logs, or chipped wood from sassafras, redbay, or other laurel-family trees, since this is a primary way the beetle is carried to new areas.
• Keep laurel-family trees in good general health with proper mulching and consistent watering during drought, since stressed trees are more attractive to bark and ambrosia beetles.
• Avoid unnecessary wounding of trunks and large limbs (string-trimmer damage, careless pruning cuts), and prune only when needed using clean practices.
• If you suspect laurel wilt nearby, have any dead or dying laurel-family trees promptly removed and the wood chipped on site or disposed of locally rather than transported.

What NOT to Do

• Do not self-diagnose. Many tree problems look alike, and treating the wrong one wastes time and can harm the tree.
• Do not apply fungicides, insecticides, or other chemicals without an arborist's specific recommendation. Wrong product or wrong timing makes things worse.
• Do not transport wood, branches, or chips from a symptomatic tree to another property, and do not prune symptomatic limbs without sanitizing tools between cuts, since both practices can carry the beetle or fungus to healthy trees.

Related Services

For most diagnosis and treatment questions, the right starting point is one of our services:

• ISA-Certified Arborist Services for diagnosis, consultation, second opinion
• Plant Health Care (PHC) for ongoing tree health management
• TRAQ Tree Risk Assessment for when the tree may be a safety hazard

Sources

This page summarizes general information from: NC State Extension, Georgia Forestry Commission, USDA Forest Service, Southern Research Station, and University of Arkansas Cooperative Extension Service.