Searching for plum flower thinner

Effect of various promising flower thinning products on plum cultivar ‘Toptaste’/Wavit in 2020 and 2021 has been tested. Evaluated products were Silwet Star (1%), Koduri (0.2%), AquaVitrin K (3%), Folicat NS (2% and 4%), and Beloukha (4.4%). The yield tree^‑1, number of fruits tree^‑1, and counted mean fruit weight were assessed. The results confirmed that all treatments thinned the flowers/fruits successfully in both years except AquaVitrin K that was efficient only in 2020. The strongest thinner was Silwet Star in the first year and Beloukha in the second year. They were able to reduce the number of fruits in comparison to control by about 69 and 86%, respectively. Surprisingly, the average fruit weight in all treatments did not differ too much from the control and the difference from control was not significant in any of the years. All the tested products appeared useful as prospective plum thinners. Both their thinning reliability and safety need to be confirmed in further experiments.