Relative abundance and fungicide resistance patterns of Botrytis cinerea and B. pseudocinerea on apple in Northern Germany

Abstract

In the Lower Elbe region of Northern Germany, low levels of fungicide resistance were recorded among Botrytis isolates obtained from blossom-end rot lesions on growing apple fruit. In contrast, isolates collected from apples affected by grey mould in storage possessed a high incidence of resistance to trifloxystrobin and boscalid (> 30% of strains) as well as elevated shares of resistance to thiophanate-methyl, iprodione, fenhexamid, fludioxonil and cyprodinil. Fluopyram resistance was rare. On the basis of fungicide resistance responses as well as BC1G_07159 gene features, B. pseudocinerea was shown to be the most frequent blossom-end rot pathogen, whereas B. cinerea was dominant as a storage rot. This pattern applied to orchards under organic as well as integrated pest management.