A 2-year research on the epidemics of the cherry leaf spot (CLS) was conducted in unsprayed cherry orchards at two locations in Bulgaria (Krichim and Gabarevo). The primary infections for both years at Gabarevo happened in mid-May during fruit development. In Krichim during 2018 the first symptoms of the disease appeared in early June (fruit ripening), while in 2019 they became evident in the second half of May (fruit development). In both locations and years, the period of a rapid increase in the CLS incidence and defoliation was from mid-June till late July. The maximum of the disease incidence and defoliation was observed in early September. More seasonal rather than regional trend in the disease dynamics was observed. In 2018 the orchards in both locations exhibited delayed the CLS progression compared to 2019 due to the relatively dry conditions in April and May. The higher disease incidence and defoliation in 2019 could be assigned to the high infection background and weather conditions in the beginning of the growing season.
Keywords: Blumeriella jaapii, epidemics progress, secondary infections, weather conditions