Abstract:
Objective A simple method to evaluate the fire blight disease resistance of pear cultivars was developed.
Method Fruits of 77 pear germplasms, including 36 cultivars and 41 hybrid progenies of Korla fragrant pear, were artificially infected with Erwinia amylovora at young, expansion, and ripening stages to examine the pathogenic responses. A protocol for grading the disease resistance of the germplasms was proposed.
Results It appeared that, 24 h after an artificial E. amylovora inoculation, the fruits at young stage more than at expansion or ripening stage displayed symptoms sufficient for an effective assessment of the resistance of the pear plants. Using the method, significant variations on the disease resistance were observed on the 77 germplasms. Of the cultivars, 13 were shown to be highly susceptible to the infection, 11 susceptible, 27 moderately susceptible, and 26 resistant (i.e., 33.77% of the total).
Conclusion The system to evaluate and determine the resistance of a pear cultivar to fire blight was developed. It was based on the response of the young fruits to a pathogenic inoculation with E. amylovora. In 24 h after the artificial infection on the fruits, 26 of the 77 sampled germplasms were determined to be resistant to the disease and could be used for breeding purposes.
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