Comparison of the shoot and blossom susceptibility of European and Asian pear cultivars to fire blight across different conditions

The susceptibility of 14 pear cultivars to the bacterium Erwinia amylovora, the causal agent of fire blight disease, was evaluated using three different methods of in vivo inoculation - the leaf inoculation method on detached shoots of pear cultivars in a climate chamber, and the terminal shoot and blossom inoculation methods on potted trees of the same pear cultivars in a net house. The results of the artificial inoculations of the European and Asian pear cultivars were compared using the susceptibility score scale, as well as the ANOVA and post hoc methods. The differences among the pear cultivar susceptibility increased during the evaluation periods in the given year, but there were no significant differences between the annual evaluation in 2020 and 2021. The results of the pear cultivar susceptibility after inoculation of the detached shoots differed significantly from the results of the terminal shoot and blossom inoculation. The detached shoot susceptibility under pathogen-favourable conditions in the climate chamber was lower than the terminal shoot and blossom susceptibility in the net house for most pear cultivars. In both years, the highest values of the terminal shoot and blossom susceptibility were coincidently calculated for the Ananaska česká European old cultivar and the Nijissejkii Asian cultivar.