Revision of the taxonomy of Grosmannia wageneri
The fungus initially described as Ceratocystis wageneri, then as Ophiostoma wageneri (EPPO A1 List) and transferred to the genus Grosmannia in 2013 (EPPO RS 2022/028) is now transferred to the genus Leptographium. This fungus causes black stain root disease on several conifer species.
Three host-specialized varieties of this pathogen were previously described: L. wageneri var. wageneri on pinyon pines (Pinus monophylla and P. edulis); L. wageneri var. ponderosum, primarily on hard pines (e.g., P. ponderosa, P. jeffreyi); and L. wageneri var. pseudotsugae on Douglas-fir (Pseudotsuga menziesii).
Morphological, physiological, and ecological differences among the three pathogen varieties had been previously determined. A recent study analysed DNA sequences to assess phylogenetic relationships among isolates from different hosts. The results support that the varieties should be elevated to species rank: L. ponderosum comb. nov., L. pseudotsugae comb. nov., while L. wageneri var. wageneri is maintained as Leptographium wageneri.
Sources
Choi D, Harrington TC, Shaw DC, Stewart JE, Klopfenstein NB, Kroese DR, Kim MS (2023) Phylogenetic analyses allow species-level recognition of Leptographium wageneri varieties that cause black stain root disease of conifers in western North America. Frontiers in Plant Science 14, 1286157. https://doi.org/10.3389/fpls.2023.1286157