2025 Effect of origin and morphological characteristics of sessile oak (Quercus petraea) seedlings on the development of Cryphonectria parasitica eng ABSTRACT: The presence of Cryphonectria parasitica on sessile oak (Quercus petraea) requires comprehensive research to understand how this fungus spreads. An experiment was conducted to investigate the impact of C. parasitica on different sessile oak stands. The experiment involved inoculating 2-year-old seedlings from 12 different half-sib lines. After 50 days, the results showed a significant difference in dieback, mortality, and dimensions of necrotic lesions among the 2-year-old sessile oak seedlings from different half-sib lines. Mortality dieback rates varied from 20% to 80% across the different half-sib lines. Seedlings from one half-sib line (8.33%) had the smallest length of necrotic lesions and the lowest dieback percentage, while seedlings from four half-sib lines (33.33%) had the narrowest width of necrotic lesions. Unlike other seedlings, the half-sib lines with smaller necrotic lesions did not experience mortality. Sessile oak seedlings’ smaller diameter and height influenced the development of narrower necrotic lesions. For the first time, this study demonstrated the potential for selecting mother trees to produce sessile oak seedlings tolerant to Cryphonectria parasitica. It also suggested that seedling dimensions can be used to indicate their sensitivity to the fungus. Keywords: Chestnut Blight Fungus, Different Hosts, Tolerance, Screening the Italian Society of Silviculture and Forest Ecology (SISEF) https://unilib.phaidrabg.rs/o:8803 doi:10.3832/ifor4669-017 ISSN: 1971-7458 http://creativecommons.org/licenses/by-nc/4.0/legalcode application/pdf 748609 bytes iForest - Biogeosciences and Forestry volume: 18 startpage: 16 endpage: 22 info:eu-repo/semantics/article Vemić, Aleksandar Lučić, Aleksandar Radulović, Zlatan Jovanović, Sanja Rakonjac, Ljubinko Popović, Vladan