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Poster: Biology & Disease Mgmt: Biological Control


Acaromyces ingoldii inhibits the laurel wilt pathogen, Raffaelea lauricola in vitro.
R. OLATINWO (1), S. Fraedrich (2) (1) USDA Forest Service, Southern Research Station, U.S.A.; (2) USDA Forest Service, Southern Research Station, U.S.A.

Laurel Wilt is a destructive disease of redbay (Persea borbonia and other species in the laurel family (Lauraceae) in the southeastern United States (US)). The disease is caused by Raffaelea lauricola, a fungal symbiont of the redbay ambrosia beetle (Xyleborus glabratus. The beetle and the fungus were introduced into the US probably with wood packing materials. This investigation was prompted by antifungal activities demonstrated by an Acaromyces species isolated from a loblolly pine bolt in Louisiana during routine laboratory microbial isolations Our objective was to evaluate the inhibitory property of the Acaromyces species against R. lauricola. We obtained isolates of R. lauricola from fresh laurel wilt infected tissues collected from sassafras trees in Louisiana and Texas, and evaluated the competitive ability of the Acaromyces and the fungistatic activities of secondary metabolites produced by the fungus against R. lauricola in vitro. Results showed a strong inhibition of R. lauricola mycelia growth by the Acaromyces species. Growth inhibition was significant as pigmented secondary metabolites produced by Acaromyces diffuses through the media. Only minimal direct competition was observed between the two fungi. R. lauricola isolates inoculated 7-day after Acaromyces, showed no growth and no spore germination. Future experiments will examine the identity, efficacy, and potential benefits of secondary metabolite(s) produced by the Acaromyces species.