Alternaria spp. and A. mali causal agents of apple leaf blotch

Alternaria leaf blotch is a widespread disease of apple and is caused by multiple species with different taxonomic status. The most frequent are species Alternaria alternata and A. arborescens species complex. Due to complex taxonomy, collecting and discussing data on the presence and distribution, significance and especially quarantine status is complicated. Currently, recommended name for pathogen causing apple leaf blotch is A. alternata apple pathotype or Alternaria spp. with small spores, while quarantine regulation is limited to the isolates capable of biosynthesis of host-specific AM-toxin. In Serbia in some years leaf and fruit spot of apples can be observed. After a multi-year sampling of diseased plants, isolates belonging to small spored Alternaria were obtained. Nevertheless, after a five year long extensive research, the presence of quarantine producing AM-toxin pathotypes (previously A. mali) was not confirmed and thus A. alternata apple pathotype is not present in Serbia.