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Research Project: Methyl Bromide Replacement: Mitigation of the Invasive Pest Threat from the American Tropics and Subtropics

Location: Subtropical Horticulture Research

Title: Laurel wilt in natural and agricultural ecosystems: Understanding the drivers and scales of complex pathosystems

item PLOETZ, RANDY - University Of Florida
item Kendra, Paul
item CHAUNDRY, ROBIN - University Of Florida
item ROLLINS, JEFF - University Of Florida
item Puig, Alina
item HUGHES, MARC - University Of Hawaii
item DREADEN, TYLER - US Department Of Agriculture (USDA)

Submitted to: Forests
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2017
Publication Date: 2/18/2017
Citation: Ploetz, R.C., Kendra, P.E., Chaundry, R.A., Rollins, J., Campbell, A.S., Hughes, M., Dreaden, T. 2017. Laurel wilt in natural and agricultural ecosystems: Understanding the drivers and scales of complex pathosystems. Forests. 8(2):48.

Interpretive Summary: Laurel wilt is a lethal vascular disease of American trees in the plant family Lauraceae, including native forest species (redbay, swampbay, and sassafras) and commercial avocado. Laurel wilt is caused by a fungus (Raffalelea lauricola) that is carried by the redbay ambrosia beetle (Xyleborus glabratus), a wood boring pest first detected in the U.S. in 2002 near Savannah, GA. Since that time, the beetle and fungus have spread throughout the Southeast, now established in nine states. Scientists from the University of Florida, University of Hawaii, USDA Forest Service, and USDA Agricultural Research Service (Miami, FL) prepared a critical review of the laurel wilt epidemic. This report summarizes our current understanding of the fungal pathogen, the beetle vectors, and susceptible host trees. It also addresses elements of disease management and identifies gaps in our knowledge base. This information will help plant pathologists and entomologists direct future research on laurel wilt, and assist action agencies in efforts to manage this deadly disease.

Technical Abstract: Laurel wilt kills members of the Lauraceae plant family in the southeastern United States. It is caused by Raffaelea lauricola, a nutritional fungal symbiont of an invasive Asian ambrosia beetle, Xyleborus glabratus, which was detected in Port Wentworth, Georgia in 2002. The beetle is the primary vector of R. lauricola in forests along the southeastern coastal plain of the United States, but other ambrosia beetle species that obtained the pathogen after the initial introduction may play a role in the avocado (Persea americana) pathosystem. Susceptible taxa are naïve (new-encounter) hosts that originated outside Asia. In the southeastern United States, over 300 million trees of redbay (P. borbonia) have been lost, and other North American endemics, non-Asian ornamentals and avocado, an important crop that originated in MesoAmerica, are also affected. However, there are no reports of laurel wilt on the significant number of lauraceous endemics that occur in the Asian homeland of R. lauricola and X. glabratus; co-evolved resistance in the region to the disease has been hypothesized. The rapid spread of laurel wilt in the United States is due to an efficient vector, X. glabratus, and the movement of wood infested with the insect and pathogen.