The search for robust varieties for sustainable fireblight management

Robust apple and pear varieties are an important tool in sustainable fireblight management. Two artificial inoculation methods are used for assessing a pome-fruit cultivar’s susceptibility to fireblight: shoot inoculation and blossom inoculation. Since 2013, Agroscope has for the first time been in a position to conduct artificial blossom inoculation tests on an outdoor trial plot that is unique in Switzerland. A correlation analysis was used to test both methods as to their comparability. A weakly positive correlation was detected, which was nevertheless not significant. Cultivars with low susceptibility in the shoot inoculation in the greenhouse also often proved to be robust in the blossom inoculation. With some cultivars, however, susceptibility in the shoot inoculation was markedly under- or overestimated compared to susceptibility in the blossom inoculation. For better transferability of the results to practice, the most promising candidate cultivars from the shoot inoculation should therefore also be tested outdoors by means of artificial blossom inoculation. The combination of the two test methods and the additional observations on the susceptibility of the cultivars from practice will allow us to make reliable recommendations of fireblight-tolerant varieties for Swiss pome-fruit production.