The leaf curl (agent - the fungus Taphrina deformans Tul.) is one of the major diseases of peach, leading to abruptly falling yields and even to complete dying of trees. Another common peach disease is the powdery mildew, caused by the fungus Sphaerotheca pannosa Lev. var. persicae Woronich. This morbus affects leaves, shoots, and fruits, which are being covered with white felty flecks. Developing cultivars with enhanced resistance to leaf curl and powdery mildew facilitates the reduction of expenses for pesticides, the improvement of ecological conditions, the enhancement of viability and commercial properties. During 2012-2016, the research included 44 peach cultivars bred by Nikita Botanical Gardens. According to research data, an enhanced and sustainable resistance to leaf curl, compared with the reference ('Sovyetskiy'), was shown by 10 0peach cultivars: 'Krymskiy Shedevr', 'Lakomiy', 'Nikitskiy Podarok', 'Blagorodniy', 'Temisovskiy', 'Druzhestvenniy', 'Naryadniy Nikitskiy', 'Progress', 'Pushistiy Ranniy', 'Champion Ranniy'. 'Krymskiy Shedevr' demonstrated the lowest vulnerability to this disease. The cultivar 'Gagarinets' has been selected owing to its enhanced resistance to powdery mildew.