Diminić, D., Kajba, D., Milotić, M., Andrić, I. and Kranjec, J. 2017. Susceptibility of Fraxinus angustifo-lia Clones to Hymenoscyphus fraxineus in Lowland Croatia. Baltic Forestry 23(1): 233-243.

   In this study on the narrow-leaved ash’s resistance to Hymenoscyphus fraxineus, significant differences were obtained between the nine tested clones, among which the clones BJ25, BJ38, NG03 and NG31 turned out to be the least susceptible to the pathogen. A significant difference was obtained between genotypes in clonal seed orchards for the leaf unfolding parameter as well. Earlier leaf unfolding was found in clone NG03, which revealed smaller necrosis development in the inoculation experiment, while the clone NG55 revealed later leaf unfolding and longer necrosis lengths, leading to the conclusion that phenology could play an important role in narrow-leaved ash clones' resistance to H. fraxineus. Preliminary results on three types of agar medium with leaf extracts from native Croatian Fraxinus species revealed that the nutrition status of the ash host could also play a role in resistance to the pathogen. The experiment revealed the fastest growth of the pathogen isolates on the agar enriched with F. excelsior leaf extract, followed by the agar with F. ornus leaf extract, while the slowest growth was obtained on the agar with F. angustifolia leaf extracts.

Keywords: narrow-leaved ash, clones, fungal pathogen, resistance.