Spring Frost Damage in Selected Sweet Cherry (Prunus avium L.) Cultivars in Central Poland: Effects of Phenological Stage, Cultivar Susceptibility and Orchard Environment

Spring frost injury in sweet cherry (Prunus avium L.) depends on the occurrence of sub-zero temperatures during sensitive stages of generative organ development. This study evaluated frost injury caused by two natural frost episodes in 2026 and the final yield of nine sweet cherry cultivars grown in two orchard environments in central Poland. The first episode occurred when flower buds were at stages ranging from visible flower buds to the balloon stage (BBCH 55–59), with minimum temperatures of −6.40 °C in Orchard A and −3.91 °C in Orchard B. The second episode occurred between full flowering and early ovary growth (BBCH 65–71), with corresponding minimum temperatures of −4.58 and −2.62 °C. Mean injury was higher in Orchard A after both episodes, reaching 45.3% and 55.3%, compared with 25.0% and 41.9% in Orchard B. Frost injury and yield were significantly affected by orchard environment, cultivar and their interaction, indicating that cultivar responses were environment-dependent. ‘Earlise’ and ‘Kordia’ were among the most severely injured cultivars, whereas ‘Staccato’, ‘Carmen’ and ‘Regina’ showed lower injury levels while maintaining comparatively high yields. BBCH stage was not significantly correlated with injury or final yield. In contrast, frost injury was strongly negatively correlated with yield after both episodes in Orchard A and after the second episode in Orchard B. These one-season findings highlight promising cultivar responses, but require validation across multiple seasons and orchard environments.