1. Nedyalkova*

Agricultural Academy, Field Crop Institute, 6200 Chirpan, Bulgaria

(Manuscript received 2 June 2023; accepted for publication 23 June 2024)

Abstract. An experiment was conducted with selected fungal isolates from different pathogenic species to induce sporulation under in vitro conditions by different additions to the nutrient medium. In pathogenicity tests and resistance studies it is important that inoculation is carried out with a spore suspension at a specific concentration rather than with a mycelium. The sporulation induction experiment performed on some isolates showed the best results with Pyrenophora tritici-repentis (sexual) and Monographella nivalis (asexual and sexual) on nettle stem segments, and with Parastagonospora nodorum and Parastagonospora avenae f. sp. triticea (asexual) on sterile filter paper and stem segments of monocotyledon (Triticum  monoccocum). Spore formation is of utmost importance in the study of fungal species, as the morphology of the sexual and asexual morphs is of high taxonomic value. This is of particular importance for species such as Parastagonospora avenae f. sp. triticea and Parastagonospora nodorum, which hardly sporulate in culture.