Petrakia liobae a novel leaf disease of beech in Europe
A novel leaf disease of beech was first observed in Switzerland and Germany in 2008 and was first thought to be the Japanese fungal species Pseudodidymella fagi (EPPO RS 2017/138). Further investigations have shown that it is a species new to science whose origin is unknown, named Petrakia liobae. Phylogenetic analysis and the re-evaluation of the two species morphological characteristics lead to the reclassification of Pseudodidymella fagi as Petrakia fagi comb. nov.
P. liobae is only known from Europe, and is currently reported from Austria, France (Pyrenees), Germany, Slovakia, Slovenia, and Switzerland on Fagus sylvatica and on F. orientalis. In Slovenia, damage to common hornbeam (Carpinus betulus) were observed in the immediate vicinity of heavily infected beech trees but pathogenicity tests were not conducted.
It is still not clear whether P. liobae is an overlooked pathogen that is causing more evident damage throughout Europe due to climatic changes or a newly introduced invasive species.
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