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See also: Laurel Wilt Disease Associated with Redbay Ambrosia Beetle for more resources

Laurel wilt is a disease of woody plants in the laurel family (Lauraceae). Hundreds of millions of redbay (Persea borbonia) trees have been killed by laurel wilt in the southeastern Atlantic Coastal Plain region of the United States (US). The disease has also killed large numbers of sassafras (Sassafras albidum) trees in forests and landscapes, and avocado (Persea americana) trees in commercial production. As of October 2019, laurel wilt was known to occur from Texas to North Carolina, south through Florida and north to Kentucky. Laurel wilt is expected to continue spreading through sassafras in the eastern US, and is a potential threat to California bay laurel (Umbellularia californica) in the western US and to lauraceous species elsewhere in the world.
See also: Region 8 - Forest Health for more information.

Laurel wilt disease has been spreading through the U.S. since 2002 and is fatal to tree species in the laurel family. Forest Service researchers are continuing to monitor the disease, search for treatment methods, and develop a better understanding of how it is affecting sassafras and other susceptible species.

See also: Publications and Multimedia Catalog for more resources

Since 2002, forests in the southeastern U.S. have struggled against a disease called laurel wilt. In 18 years, laurel wilt has spread to 11 southeastern states and killed hundreds of millions of trees. A review article by USDA Forest Service scientist Rabiu Olatinwo reflects on the origins and spread of laurel wilt throughout the last several years. Olatinwo, a research plant pathologist at the SRS, published this research with recently retired plant pathologist Stephen Fraedrich and research entomologist Bud Mayfield in the journal Forests.

The Tennessee Department of Agriculture (TDA) is advising forest landowners to monitor their sassafras trees after detecting new cases of laurel wilt disease in Robertson and Hamblen Counties. In the last quarter of 2019, the disease was detected in trees in Montgomery, Cheatham, Dickson and Williamson Counties. "These new detections of this invasive disease show a significant geographic jump across the state," State Forester David Arnold said. "This is yet another unfortunate example of an invasive pest impacting our forests. Landowners should take caution to prevent the spread of this disease if detected on their property."

Laurel wilt is a fungal disease caused by an invasive pathogen, Raffaelea lauricola, which can affect a range of plants, including sassafras and spicebush in Tennessee. Choked of water, trees wilt and die within a few weeks or months. Currently, no treatment has been developed that can cure laurel wilt disease or protect trees from infection. The best way to prevent the spread of laurel wilt is to avoid movement of firewood or other untreated timber. Tennesseans are urged to monitor their sassafras trees for browning of leaves, leaf loss, and staining in the inner bark. If you suspect your trees might have laurel wilt disease, contact Forest Health Program Specialist Sam Gildiner at 615-837-5439 or sam.gildiner@tn.gov. TDA Division of Forestry staff will assist in identifying the disease and recommending management actions, if appropriate.

The Laurel Wilt Public Dashboard story map – a collaboration between the Georgia Forestry Commission, multiple branches of the Forest Service, and other state forestry agencies – shows the annual spread of the disease. The story map shows that new detections occur mostly in the Coastal Plain, not in the Appalachian mountains where sassafras reaches its greatest sizes.

View the updated regional infestation map for Laurel Wilt Disease (for initial detection in May 2002. Map is updated periodically (USDA, FS - Forest Health).  Select "Counties Infected By Year" tab.

Laurel wilt has devastated plants in the Lauraceae family – redbay, sassafras, pondberry, avocado, and others – since it was first detected in the southeastern U.S. around 2002. There is no widespread, effective treatment for laurel wilt. Genetics research is focused on learning more about the pathogen's genetic structure in order to improve detection methods and screening for possible resistance in Lauraceae host species. "We have developed genetic markers to describe the population of the pathogen in the U.S.," says USDA Forest Service plant pathologist Tyler Dreaden. "Knowing which genotypes to use contributes to a quicker, more cost-effective resistance screening process." Dreaden led a new study to shed light on the genetic structure of the pathogen and its reproductive strategy. The research team included Marc Hughes at the University of Hawaii at Manoa, Randy Ploetz and Jason Smith at the University of Florida, and Adam Black, horticulture director of the Peckerwood Garden Conservation Foundation in Texas. Their findings were published in Forests.

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