The Influence of Genotype and Morphological Characteristics of Rowan ( Sorbus aucuparia ) Leaves on the Development of Gymnosporangium cornutum

Rust caused by Gymnosporangium cornutum Arthur ex F. Kern is one of the most common diseases of rowan ( Sorbus aucuparia L.). Currently, there is little information on the development of this disease in forestry literature. In order to eliminate this deficiency, the examination of the influence of Sorbus aucuparia genotype and leaf dimensions on the occurrence and abundance of aecia of Gymnosporangium cornutum was carried out. The genotype had a statistically significant influence on aecia occurrence, while leaf length, width, circumference, and area had a statistically significant influence on aecia abundance. About 10% of Sorbus aucuparia genotypes showed greater tolerance to Gymnosporangium cornutum , with a nearly 4-fold lower probability of aecia occurring on leaves. Larger leaves of Sorbus aucuparia sensitive genotype had a greater Gymnosporangium cornutum aecia abundance compared to smaller leaves. The results obtained for the first time indicate the possibility of selecting and producing reproductive material of Sorbus aucuparia tolerant to Gymnosporangium cornutum .