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The notable difficulties in the morphological identification of phoma-like fungi haveresulted in a poor understanding of the generic and species boundaries in this group of organisms.In most available mycofloristic and phytopathological studies, there is no reliable information onthe distribution of certain nonspecialized phomoid species on cultivated crops or wild plants. Boththe revision of existing data on the biodiversity and geographical distribution of phoma-like fungiassociated with Asteraceae in Russia and the acquisition of new knowledge according to modernconcepts of these fungi are therefore of great significance. The aim of this study was to identifyphoma-like strains from Asteraceae based primarily on phylogenetic analyses of the sequences offour loci (ITS, LSU, TUB, RPB2) as well as on traditional morphological approaches. The resultingphylogenetic trees revealed six well-supported monophyletic clades corresponding to six genera inthe family Didymellaceae: Ascochyta, Boeremia, Didymella, Neoascochyta, Nothophoma, andStagonosporopsis. The isolates were identified as As. kamchatica, B. exigua, B. exigua var. forsythiae,B. exigua var. linicola, D. americana, D. glomerata, D. macrophylla, D. pinodella, D. pomorum,D. rosea, Ne. desmazieri, Ne. paspali, No. quercina, St. dennisii, and St. inoxydabilis. Ascochytakamchatica sp. nov. was described as a new species. Three Didymella species (D.pinodella from Cirsium arvense, D. rosea from Sonchus arvensis, and D. macrophylla from Taraxacumofficinale), two Neoascochyta species (Ne. desmazieri from T. officinale and Ne. paspali fromAchillea millefolium) and St. dennisii from T. officinale were the first records of these phoma-likefungi in Russia.

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Giant hogweed is one of the most widespread invasive alien species of the Baltic region. The pycnidial fungus, Calophoma complanata is being evaluated as a potential bioherbicide for control of Heracleum sosnowskyi. The aim of this work is to evaluate an ability of the potential mycoherbicide C. complanata MF-32.121 to overwinter in the conditions of Saint Petersburg area. Plants inoculated by C. complanata MF-32.121 successfully survives wintering in the conditions of Saint Petersburg area. Pearl barley covered by C. complanata MF-32.121 mycelium successfully survives wintering in the same conditions as well. When favorable conditions have arisen, the C. complanata MF-32.121 mycelium is capable to infecting young giant hogweed. Moreover, it was revealed that a change in the biochemical composition, namely, an increase in the level of trehalose, contributes to the manifestation of a greater tolerance of C. complanata MF-32.121 mycelium to temperature-humidity conditions.