Evaluating Late Spring Frost Damage at Sweet Cherries and Apples from Bistrita Fruit Region, Northern Transylvania, Romania

Changing climate patterns especially in spring, negatively influences the flowering process, hence the yields in stone and pome fruits. During flowering period in sweet cherry orchard (BBCH 60-65) negative temperatures were recorded in five consecutive days between 06-11.04.2025, culminating with -5.5 ⁰C, which caused important fruit losses. In the present study we investigate the effects of frost on flower buds of ‘Tamara’, ‘Kordia’, ‘Lapins’ cultivars grafted on ‘GiSelA 3,5,6’ rootstocks in different combinations and several autochthonous (‘Cociuvaș’, ‘Tentant’, ‘Superb’, ‘Severin’, ‘Adreiași’, ‘Spectral’, ‘Daria’, ‘Ludovan’, ‘Romaria’, ‘Jubileu 30’) as well as foreign cultivars (Sweatheart, Bigareau Burlat) grafted on ‘IP-C5’ and ‘IP-C7’ rootstocks. Sweet cherry trees in the research plots showed significant frost damage, with cultivars sufefring a yield loss of 98-100%. The damage caused within apple trees had the same pattern, whereas over 90% of floral buds were severely affected. The apple trees which were between the green bud stage (BBCH 56) and the pink bud stage (BBCH 57) phenophases, suffered severe frost damage. The cultivars 'Willtons Star Red Jonaprince Select Eco'/B9 and 'Golden Reinders'/M9 were severely affected. The complex planting system, cultivars, rootstocks, location of the orchard, the age of trees, influenced the different frost resistance of cultivars and species.