First report of Diaporthe convolvuli on field bindweed (Convolvulus arvensis) in Russia

Convolvulus arvensis (field bindweed) is a widely distributed and harmful weed in Russia. The fungal strains MF-SOR 61.20.1 and MF-SOR 61.20.2 were isolated from the visually healthy leaves of C. arvensis collected in northwest Russia (Saint Petersburg, Pushkin) and initially identified by morphological features as Diaporthe sp. The aim of this study was to identify these strains using molecular genetic, micromorphological, and cultural characteristics, and to assess their pathogenicity. Multilocus phylogenetic analysis, based on sequences of the internal transcribed spacer (ITS) of rDNA, as well as partial calmodulin (cal), histone 3 (his3), translation elongation factor 1α (tef1), and β-tubulin (tub2), allowed definitive identification of these strains as Diaporthe convolvuli. Pathogenicity assays demonstrated that strains were pathogenic to C. arvensis, causing necrosis on leaf segments under laboratory conditions. The pathogenicity was confirmed by reisolation of D. convolvuli from infected leaves. To our knowledge, this is the first finding of this fungus in Russia (Saint Petersburg, Pushkin). This study provides the first description, refinement, and comprehensive illustration of the fungus's cultural and micromorphological characteristics since 1988.