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Abstract
Cercospora liquidambaris, Pseudocercospora liquidambaricola and Pseudocercospora turberculans have been described as causing a leaf spot disease on American sweetgum (Liquidambar styraciflua). A leaf spot disease on Chinese fringe flower (Loropetalum chinense) has also been attributed to P. liquidambaricola in China. A formal report of this pathogen on loropetalum in the USA has not been completed. Confusion in pathogen identity has implications for regulatory and management issues. Isolates collected from leaf spot-infected sweetgum and loropetalum were compared morphologically, phylogenetically, and through cross-inoculation. The ITS, ACT, EF-1, and LSU gene regions were sequenced. Isolates from sweetgum and loropetalum separated into two phylogenetic groupings. Morphologically, sweetgum isolates were similar to the description of P. liquidambaricola, while loropetalum isolates had characteristics distinctly different. Sweetgum and loropetalum isolates were not cross-pathogenic. An in-vitro fungicide sensitivity assay also revealed possible fungicide resistance developing in loropetalum leaf spot isolates to the benzimidazole fungicide, thiophanate methyl.