First Report of Powdery Mildew Caused By Erysiphe Cruciferarum on Camelina Sativa in Bulgaria

Summary

Camelina (Camelina sativa L. Crantz) belongs to the Cruciferous family and is a relatively new crop for Bulgaria. At the end of June of the same year, symptoms of powdery mildew (Erysiphe cruciferarum Opiz ex L. Junell) were detected, with an attack rate exceeding 40%. A white mycelium was observed on the upper side of the leaves and the stems, later the leaves turned yellow. The structure of the white colonies with hyphal growth is observed under a microscope. Conidiophores are cylindrical, 19.9 to 41.7 × 8 to 17.1 μm and composed of 3 to 4 cells. The chasmothecia of the pathogen was also discovered. Fruiting bodies are 110 µm (80-130 µm) in diameter, with colourless, club-shaped asci with colourless, ovoid ascospores. Pathogenicity experiments performed according to Koch's rules were conducted in a greenhouse at 22 °C, 14 h photoperiod and 70 % humidity. As a result, the typical symptoms of powdery mildew appeared 8 days post-infection. It was re-isolated and identified by morphological characteristics. Partial sequence analysis of the ITS5 - 5.8 - ITS4 region of the nuclear ribosomal DNA with universal primers identified the pathogen as E. cruciferarum. The phylogenetic tree was built using the neighbour-joining by BLAST software. According to the literature, the article is the first report of powdery mildew caused by E. cruciferarum on camelina in Bulgaria.