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Poster: Epidemiology: Pathogen-Vector Interations


First report of laurel wilt on sassafras in Arkansas
R. OLATINWO (1), C. Barton (2), J. Hwang (3), W. Johnson (3) (1) USDA Forest Service, Southern Research Station, U.S.A.; (2) Arkansas Forestry Commision, U.S.A.; (3) USDA Forest Service, Forest Health Protection, U.S.A.

Laurel wilt, caused by the fungus Raffaelea lauricola T.C. Harrin., Aghayeva & Fraedrich, is a lethal disease of redbay (Persea borbonia (L.) Spreng.), sassafras (Sassafras albidum (Nutt.) Nees), and other species in the laurel family (Lauraceae). The fungus is transmitted by an exotic ambrosia beetle (Xyleborus glabratus Eichh.) native to Asia introduced into the United States in 2002. It was first reported at Port Wentworth, Georgia and rapidly spread across the south causing extensive redbay mortality. On December 2, 2015, visit to a landowner in Bradley County near Warren, Arkansas (33.64511°N, 92.05134°W) led to the first reported mortality of sassafras caused by laurel wilt in Arkansas. Moderate degrees of staining and beetle galleries were found from symptomatic trees at this location. Suspect beetles collected from sapwood of affected trees were later identified as X. glabratus. The presence of R. lauricola was confirmed by morphological characterization and molecular identification of cultures obtained from stained sapwood tissues. This is the first report of laurel wilt on sassafras or any other Lauraceae species in Arkansas. In 2014, laurel wilt was reported on sassafras in northern Louisiana (83 miles southwest). This new report in Arkansas may indicate northward movement of the disease into natural habitat of sassafras. However, the lack of redbay (a more attractive host) in this region may slow the northward spread of laurel wilt in Arkansas.