Evaluation of the Resistance of Malus Germplasm to Bot Canker Caused by Botryosphaeria dothidea

摘要

The resistance of 240 Malus germplasm accessions to bot canker was evaluated by inoculating branches in the field with cultured mycelia from five pathogenic isolates of Botryosphaeria dothidea. Differences in the disease resistance were significant among the examined germplasm accessions and the different pathogenic isolates. In general, the resistance of the wild species and the Chinese domestic cultivars was much stronger than that of the cultivars or mutants of Malus x domestica. Baccata HR, a genotype from a wild species, is highly resistant. Three M. x domestica cultivars/mutants, Maypole, Spy227 and Fengyan, are resistant, whereas Changhong is highly susceptible. A wide range of resistance levels were observed among the 28 M. sieversii genotypes. Differences in resistance were also found among clonal mutants from cultivars of M. x domestica. The disease indices of the same germplasm in response to different pathogenic isolates of B. dothidea are sometimes significantly different.