The development of the growth and ripening processes is the determining factor in achieving the quality of the fruits and the duration of its maintenance during the post-harvest period and correlates with the intensity of the metabolic processes. The rhythm, speed and duration of the metabolism of growth and development are influenced by agro-climatic conditions and the application of multiple modern agrotechnical processes, including foliar treatments. Foliar treatments of plum trees with the natural growth regulator Reglalg and microelements B, Zn, Mn, Mo, applied during the growing season, favor photosynthetic activity and respectively the accumulation of assimilates in trees and plum fruits, participating in the formation of organic compounds: soluble and insoluble solids, carbohydrates and vitamin C in plum fruits at the stage of removable maturity.