Cultural and morphological characteristics of causal agents of Cytospora canker of apple trees in Kazakhstan

This study provides a morphological description of Cytospora spp. isolates collected from apple tree branches affected by Cytospora canker. Cytospora canker is a globally widespread disease caused by highly aggressive pathogens that induce cankers in woody plants within both natural and agro-ecosystems. In severe cases, cankers can lead to the dieback of branches and trees. This article presents the first report of Cytospora sorbina and Cytospora parasitica species identified in intensive apple orchards of Almaty region, Kazakhstan. Notably, the species composition, as well as the morphological and genetic characteristics of Cytospora spp. pathogens causing Cytospora canker in Kazakhstan, remain understudied. Consequently, this study examined the cultural and morphological properties of Cytospora canker pathogens, including determining optimal growth media and temperature conditions for these pathogens. For microbiological analysis, samples were collected from five intensive apple orchards in the Almaty region, yielding 15 fungal isolates from the following apple varieties: Gala, Granny Smith, Golden Delicious, Golden Rush and Fuji. Based on morphological and cultural characteristics, the isolates were identified as Cytospora sorbina and Cytospora parasitica. The results showed optimal growth conditions at 27°C on potato dextrose agar (PDA). This study provides insights into the host-pathogen biological interactions, potentially facilitating improvements in early diagnostics and the development of integrated disease management strategies against Cytospora-related diseases to protect apple orchards.