Date of Award

December 2021

Document Type


Degree Name

Master of Science (MS)


Forest Resources

Committee Member

Jess Hartshorn

Committee Member

Albert Mayfield

Committee Member

Julia Kerrigan


The laurel wilt disease complex consists of a beetle vector (redbay ambrosia beetle (RAB); Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae)), a symbiotic fungus and tree pathogen (Raffaelea lauricola (Ophiostomataceae) T.C. Harr., Fraedrich & Aghayeva), and host trees (Lauraceae). RAB originated from Asia and was first discovered in the United States near Savannah, Georgia in 2002. RAB deposits R. lauricola in host trees, including redbay (Persea borbonia) and sassafras (Sassafras albidum), when females tunnel into trees to lay eggs. Xyleborus glabratus attacking sassafras may have far reaching ecosystem impacts due to the expansive range of sassafras in the eastern United States and RABs ability to survive low temperatures. Our objectives were to determine how laurel wilt disease ecology differs in sassafras vs redbay. Specifically, we examined laurel wilt ecology in redbay and sassafras along the leading edge of disease by 1) examining patterns of RAB attack and brood productivity on redbay and sassafras stems and 2) examining the movement of R. lauricola through sassafras roots in the absence of RAB. Overall, there was a clustered pattern of RAB attack on host stems with beetles attacking the North and South faces of sassafras but not redbay. Redbay trees had lower moisture content and more beetle emergence than sassafras. Raffaelea lauricola does have the ability to move via sassafras roots. Site 3 had the most symptomatic trees and mortality, however, site consists of many variables, so the specific environmental variables driving these changes is unknown. Distance from the inoculated tree impacted the final crown condition with the class 0 to <10 ft being the most consistently affected.



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