Photographer: Ronald F. Billings
Laurel wilt is a deadly disease of redbay (Persea borbonia) and other tree species in the Laurel family (Lauraceae). Laurel wilt has been confirmed in the field on several other Lauraceous hosts including avocado (Persea americana), sassafras (Sassafras albidum), camphor (Cinnamomum camphora), and the endangered species pondberry (Lindera melissifolia) and pondspice (Litsea aestivalis). The disease is caused by a fungus (Raffaelea lauricola) that is introduced into host trees by a non-native insect, the redbay ambrosia beetle (Xyleborus glabratus), that was first detected in the United States near Savannah, Georgia, in 2002. The beetle is believed to have been introduced in wooden crating material imported through the shipment of goods from its native range in southeast Asia. The fungus plugs the water-conducting cells of an affected tree and causes it to wilt. Laurel wilt has caused widespread and severe levels of redbay mortality in the Southeastern coastal plain.
Symptoms: Trees with laurel wilt initially exhibit drooping foliage with a reddish purplish discoloration in a portion of the crown. The symptoms will gradually cover the entire crown and turn brown in color. Wilted leaves may remain on the infected trees for year or more.
In the early stages of the disease, a wilting tree may not show any obvious signs of ambrosia beetle attack. Early attacked are inconspicuous and may happen on branches in the crown or on the stem. As the tree dies from the fungal infection, it is colonized by more ambrosia beetles which produce small dowels or "toothpicks" of sawdust protruding from the stem as they bore into the wood.
Distribution: Laurel wilt can spread in at least two ways: one is via the beetle's natural reproduction and migration. A second way is through the sale and transport of beetle-infested wood, a result of redbay's use as firewood and for outdoor grilling. As of August 2009, laurel wilt has been found in South Carolina, Georgia, Florida and Mississippi.
|Distribution of Counties with Laurel Wilt Disease Symptoms, by Year of Initial Detection - Updated September 2011. Click to enlarge picture|
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Forest Health Notes:
Host Trees: In addition to redbay, other hosts of the laurel wilt fungus that have been confirmed from diseased plants in the field include swamp bay, avocado, sassafras, pondspice, pondberry and camphor tree.
Click links below to read more on each species
Other Links: Read more about the Abrosia Beetle
Laurel Wilt - Forest Health Protect, Southern Region, USDA Forest Service Web site
Laurel Wilt - Florida Department of Agriculture & Consumer Services, Division of Forestry, Forest and Shade Tree Pest, Leaflet Number 13, Published April 2008.
Redbay Ambrosia Beetle-Laurel Wilt Fungus: A Potential Major Problem for Florida Avocados. Jonathan H. Crane and Jorge Pena, University of Florida.
Forest Health Articles Related to Laurel Wilt and Redbay Ambrosia Beetle:
Laurel Wilt Potential Threat To Mississippi? (Posted 11/05/2007)
Laurel Wilt Disease Or “An Ecological Disaster” - Extinction of Red Bay Trees in the Southeast (Posted 6/24/2008)
Redbay Wilt or Laurel Wilt (Posted 8/25/2008)
The Unnecessary Extinction of the Redbay, a Defining Southern Tree (Posted 8/25/2008)
Update 2011 - Redbay Ambrosia Beetle and Laurel Wilt Disease in Mississippi (Posted 11/1/2011)
Report redbay and sassafras tree deaths in your area to your local office of the Mississippi Forestry Commission.
District Forester, Southwest
P.O. Box 749
515 County Farm Lane NE
Brookhaven, Mississippi 39602-0749
(601) 833-6621 office